Utilization of enzyme treated wheat bran in making pasta with high fiber content

VIETNAM NATIONAL UNIVERSITY SYSTEM HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY FACULTY OF CHEMICAL ENGINEERING DEPARTMENT OF FOOD TECHNOLOGY a c2 MASTER’S THESIS UTILIZATION OF ENZYME-

VIETNAM NATIONAL UNIVERSITY SYSTEM

HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY

FACULTY OF CHEMICAL ENGINEERING DEPARTMENT OF FOOD TECHNOLOGY

a c2

MASTER’S THESIS

UTILIZATION OF ENZYME-TREATED WHEAT BRAN IN MAKING PASTA

WITH HIGH FIBER CONTENT

Specialization: FOOD TECHNOLOGY

Supervisor: Prof Dr LE VAN VIET MAN

Ho Chi Minh City, July 2019

ĐẠI HỌC QUỐC GIA TP HCM

TRƯỜNG ĐẠI HỌC BÁCH KHOA

NGUYÊN SĨ NHẬT

NGHIEN CUU SU DUNG CAM LUA MI DA

XU LY ENZYME TRONG SAN XUAT

MI PASTA GIAU CHAT XO

Utilization of enzyme-treated wheat bran in

making pasta with high fiber content

Chuyén nganh: CONG NGHE THUC PHAM

Mã số: 8540101

LUẬN VÁN THẠC SĨ

TP Hồ Chí Minh, tháng 07 năm 2019

CÔNG TRÌNH ĐƯỢC HOÀN THÀNH TẠI TRƯỜNG ĐẠI HỌC BÁCH KHOA - ĐHQG TP HCM

Cán bộ hướng dan khoa hoc: GS TS LE VAN VIET MAN

Cán bộ chấm nhận xét 1: PGS TS HOÀNG KIM ANH

Cán bộ chấm nhận xét 2: TS LÊ MINH HÙNG

Luận văn thạc sĩ được bảo vệ tại Trường Đại học Bách Khoa, ĐHQG

TP HCM ngày 10 tháng 7 năm 2019

Thành phần Hội đồng đánh giá luận văn thạc sĩ gồm:

1 PGS TS LE NGUYEN DOAN DUY

2 PGS TS HOANG KIM ANH

3 TS LE MINH HUNG

4 PGS TS TON NU MINH NGUYET

5 TS NGUYEN QUOC CUONG

Xác nhận của Chủ tịch Hội đồng đánh giá luận văn và Trưởng Khoa quản lý chuyên ngành sau khi luận văn đã được sửa chữa (nêu có)

ĐẠI HỌC QUỐC GIA TP.HCM CỘNG HÒA XÃ HỘI CHỦ NGHĨA VIỆT NAM TRƯỜNG ĐẠI HỌC BÁCH KHOA Độc lập - Tự do - Hạnh phúc

NHIỆM VỤ LUẬN VÁN THẠC SĨ

Họ tên học viên: NGUYÊN SĨ NHẬT .-.:-5zc5¿ MSHV:1870472

I TÊN ĐÈ TÀI: Nghiên cứu sử dụng cám lúa mì đã xử lý enzyme trong sản xuất mì

H NHIỆM VỤ VÀ NỘI DUNG: 1) Tổng quan tài liệu . 2-5-5255 52 s55 s52

2) Khảo sát ảnh hưởng của việc bo sung cam lua mi đến chất lượng của mì pasta, bao gồm

3) Khảo sát ảnh hưởng của việc bổ sung chế phẩm gluten và xử lý bằng transglutaminase đên chât lượng của mì pasta giàu chât xơ, bao gôm thành phân hóa học, tính chât công

nghệ, màu sắc, tính chất cơ lý và mức độ ưa thích chung .- - +52 2 552

HI NGÀY GIAO NHIỆM VỤ: 15/01/2019 - 5-5: 2252 SE EkEEkErrrkrkrrkrrerree

IV NGÀY HOÀN THÀNH NHIỆM VỤ: 15/06/2019 2 5s szsrxrveevsee

V CÁN BỘ HƯỚNG DẪN: GS TS LÊ VĂN VIỆT MÃN . - 5 s2 scs+se¿

Tp HCM, ngày 01 tháng 07 năm 2019

CÁN BỘ HƯỚNG DẪN CHỦ NHIỆM BỘ MÔN ĐÀO TẠO

TRUONG KHOA KY THUAT HOA HOC

(Họ tên và chữ ký)

PHAN THANH SƠN NAM

Declaration

I declare that this thesis presented for the Master’s degree in Food Technology, has i) been composed entirely by myself

2i) been solely the result of my own work

31) not been submitted for any other degree or professional qualification

Ho Chi Minh City, July 29" 2019

NGUYEN SI NHAT

Acknowledgement

I would like express my gratitude to my supervisor, Professor Le Van Viet Man, who helped me with the experimental design as well as revision of the manuscript I am deeply thankful for his valuable instruction and support during the time doing research I also would like to thank my friends who accompanied me through this long journey and offering endless support Finally, I am grateful to my mother for her unconditional love and wholehearted encouragement

Abstract

Wheat bran is a by-product of the milling process This material is rich in protein, minerals and dietary fiber However, it has been mainly used as animal feed and fertilizer

In our previous research, wheat bran was treated with cellulase preparation and employed

in the production of a high fiber pasta by partially replacing the semolina portion In this study, the antioxidant activity and glycemic index of the wheat bran-fortified pasta were investigated Additionally, the potentials of vital gluten addition and transglutaminase treatment in improving quality of bran-enriched pasta were also examined The inclusion

of wheat bran into flour formulation improved the antioxidant activity of pasta in terms

of total phenolic content, DPPH radical scavenging activity and ferric reducing power; as well as reducing the glycemic response of pasta The fortification of gluten preparation and use of transglutaminase enhanced the cooking performance as well as the firmness, tensile strength and overall acceptability of pasta In particular, the combination of vital gluten addition and transglutaminase treatment was more effective in enhancing cooking loss, firmness and tensile strength

11

Table of Contents

Declaration .eccececccescceeseceeseecssceesscecaccesaecesaeessnseseeeceneeceeeseseeseseeesaeessaeessaeeeeesseeeesesesanesseeesseeesees i

19401 4Is91 4290) cv 0 ii

0 r1 0n 11 List Of Tables 0.0.2 vi I8 0s vn

2 Literature 2n ố ố 2

2.1.1 Definition, classification and physiological effects of dietary fiber 2

2.1.3 Conversion of insoluble fiber into soluble fiber by enzymatic treatment 3 2.1.4 Application of cellulase and xylanase preparations in processing of cereal brans 4

2.2.1 Technology of making pasta with high fiber con€nIf - «<< =<<+seexseeeees 5

2.3.3 Improvement in pasta texture by the use of transglutaminase preparation 8

4 Results and Discussion nẽ ẽ 25 4.1 Proximate composition, color, and antioxidant activity 0ƒ raw mmaferials 25

4.1.3 Antioxidant activity Of raW TTIAE€TI44ÌS < =5 << + + + + vs vn vn nen 26 4.2 Effects of wheat bran incorporation on the qualities 0Ÿ D(SÍđ sex 27

4.2.3 In vitro starch digestion and predicted glycemic Index of pasfa 29

4.3 Effects of vital gluten addition and transglutaminase (TG) treatment on the qualities of z2 PẼẺẼẺ 32

hs ta vao in nh cố 32

76 9.0 vi ch ố 34

4.3.3 Texture an ae 35

4.3.4 Color co hố 38

4.3.5 Overall acceptabIÏIfy - - cv nọ Họ nh nh me 40 5 Conclusion and Sugges(Ï0T - - - <5 + sx s TH ng ni ga 42 6 Appendix: Supplementary đa£a - - - Ăn ch HH HH re 43 (09,4 44

Antioxidant activity of uncooked pasta sampπs - 5 << << se sessss.esse 28

Color parameters of uncooked pasta sarmpÏes .- - 5 5< se =+<se++se+sseessx 39

Percentage of starch hydrolyzed during ¡n yifro digestion of pasta samples 43 Kinetic parameters of starch hydrolysis during in vitro digestion of pasta samples 43 Area under curve (AUC) and hydrolysis index (HI) of pasta samples 43

List of Figures

Vii

List of Acronyms

1 Introduction

Pasta from durum wheat is a common staple food in many countries It is regarded as a healthy food due to its relatively low fat composition and having a good source of low glycemic index carbohydrate However, the dietary fiber content of pasta

is low, only 1.2% (C S Brennan, 2013) To resolve this problem, pasta is prepared from wholegrain or incorporated with inulin, B-glucan and other ingredients to increase the fiber content (Foschia, Peressini, Sensidoni, & Brennan, 2013) Another potential source

of dietary fiber for human consumption is wheat bran This cereal material has the content

of total dietary fiber up to 63.0% (Onipe, Jideani Afam, & Beswa, 2015) Nevertheless, 90% of wheat bran has been mainly used for animal feeding worldwide (Song, Zhu, Pei,

Ai, & Chen, 2013) Apart from this, the ratio of insoluble dietary fiber to soluble dietary fiber (IDF/SDF) of wheat bran is highly unbalanced, which is about 7:1 On the nutritional perspective, it is advised to lower this ratio in order to maximize the beneficial effects of dietary fiber, including weight control and reduction in the risk of developing type 2 diabetes, cardiovascular diseases, and colonic cancer (Jha, Singh, & Prakash, 2017)

In our previous study, pasta products with high fiber content was produced by introducing wheat bran into the formulation (Si Nhat & Thi Cam Tu, 2018) Notably, pasta containing bran treated with cellulase preparation exhibited a high soluble fiber content and a balanced IDF/SDF ratio In the mentioned research, the effects of bran inclusion on pasta quality in terms of dietary fiber content, cooking performance, texture, and overall acceptability were assessed However, the changes in other properties of interest, i.e antioxidant activity and glycemic response, were not yet measured On the other hand, the most challenging problem of incorporating wheat bran into pasta is the adverse impact on textural quality, mainly due to the disrupted protein network The deterioration in pasta texture also correlated with the reduction in overall acceptability of consumers Thus, enhancement in textural properties of bran-enriched pasta is of high importance

This research aims to investigate the impacts of fortifying enzyme-treated and untreated wheat bran on the antioxidant activity and in vitro starch digestion of pasta product Additionally, this study also examines the feasibility of using transglutaminase treatment and vital gluten addition as improvement solutions in manufacturing of bran- enriched pasta

2 Literature review

2.1 Dietary fiber

2.1.1 Definition, classification and physiological effects of dietary fiber

Dietary fibers are carbohydrate polymers with three or more monomeric units and not hydrolyzed by the endogenous enzymes of the human small intestine (Joint FAO/WHO Food Standards Programme, 2015) Based on their solubility in water, dietary fibers can be classified into insoluble and soluble dietary fibers Lignin, cellulose, and some hemicelluloses belong to the insoluble dietary fiber; while pectic polysaccharides, B-glucans, galactomannans, fructans, gums, and other non-starch polysaccharides are the representatives of soluble dietary fiber (Maphosa & Jideani, 2016)

Insoluble and soluble dietary fibers have different effects on normal gut activity The insoluble fibers are neither digested nor fermented in the gastrointestinal tract They are mainly responsible for absorption, swelling and holding of water molecules within their porous structures (Mudgil, 2017) The hydration of insoluble fibers may result in increased fecal bulk and softened stool, therefore improving proper bowel movement and facilitating laxation (Foschia et al., 2013) In contrast, the soluble fibers are fermented by the colonic microbiota in the large intestine with various extents Some of them are slowly fermented and exert laxative effect, whereas the others are rapidly fermented and serve

as substrates for potentially beneficial bacteria (McRorie, 2015) Such soluble fibers selectively stimulate the growth and activity of these microorganisms, thus enhancing the host health This phenomenon is clinically designated as prebiotic effect (Slavin, 2013)

Certain soluble fibers such as B-glucan, psyllium and guar gum may increase the viscosity of the aqueous phase when ingested The consumption of this kind of fibers might lead to the decrease in the plasma cholesterol level and glycemic response (Stephen

et al., 2017) The mechanism by which those fibers can lower the serum cholesterol level

is the entrapment and elimination of bile via the stool (McRorie, 2015) In addition, the attenuation of glycemic response by soluble fibers could be explained by the limited contact between digestive enzymes and complex substrates due to the elevated viscosity, which in turn impedes the degradation of macromolecules into readily absorbed nutrients (McRorie, 2015) As a consequence, the absorption of glucose and other nutrients at the

brush border of small intestine is slowed.

It can be noted that more physiologically beneficial effects are associated with the consumption of soluble fiber compared to insoluble fiber The ratio of insoluble fiber

to soluble fiber (IDF/SDF) provides an important information about the nutritional quality

of foods The American Dietetic Association recommends a dietary fiber intake of 25—30 g/day for adults, in which an IDF/SDF ratio of 3:1 is advised to maximize potential health benefits of dietary fiber (Valdivia-L6pez & Tecante, 2015) Other authors suggested that

a source of dietary fiber should have an IDF/SDF ratio close to 2:1 to be accepted as a food ingredient (Rafiq et al., 2016)

2.1.2 Wheat bran—A potential source of dietary fiber

The wheat (Triticum spp.) kernel is made of 03 major components, i.e the bran, the germ and the endosperm During the conventional milling process of wheat grain, the majority of endosperm is separated from the germ and the bran Wheat bran occurs as a milling by-product Histologically, the bran comprises different tissue layers, namely the fruit coat, the seed coat, the hyaline layer, and the aleurone layer—a part of the starchy endosperm (Apprich et al., 2014) Wheat bran is considered as a concentrated source of dietary fiber The total dietary fiber content of this cereal material varies between 33.4 and 63.0% The proportion of each constituent in the total fiber content of wheat bran is shown in Table 2.1 The soluble portion of wheat bran fiber is less than 5% and consists

of glucans and xylans (Onipe et al., 2015) The IDF/SDF ratio of wheat bran is apparently unbalanced and higher than the advised value Therefore, it is recommended to reduce this ratio by enzymatic treatment

Table 2.1 Dietary fiber components in wheat bran (Hemdane et al., 2015)

2.1.3 Conversion of insoluble fiber into soluble fiber by enzymatic treatment

The use of specific endocarbohydrase could be a feasible strategy for conversion

of insoluble dietary fibers into soluble fibers Concerning insoluble polysaccharides, the cleavage of internal glycosidic linkage by endocarbohydrases may lead to the formation

of short-chain molecules, which could be soluble in water On the contrary, the action of exohydrolases may result in the formation of low molecular weight carbohydrates Thus,

in order to minimize the transformation of fibers into undesired sugars, the presence of exocarbohydrase activity in the enzyme preparation with a large amount is not preferred

In cereal brans, xylan and cellulose are the most abundant insoluble fibers (Mudgil & Barak, 2013) Hence, utilization of xylanase and cellulase preparation may be useful for transforming insoluble fibers of brans into soluble fibers

Xylanases are a group of carbohydrase that catalyze the hydrolysis of xylan Xylanase preparation are mostly produced by bacteria and filamentous fungi Due to the heterogeneity and complicated chemical nature, the complete breakdown of xylan requires the action of several enzymes The xylanolytic enzyme system usually includes B-1,4-endoxylanase; B-xylosidase, acetyl xylan esterase, arabinase, a-glucuronidases, ferulic acid esterase, and p-coumaric acid esterase (X Liu & Kokare, 2017) All of these enzymes act cooperatively to hydrolyze xylan into constituent monomers Endoxylanase (EC 3.2.1.8) is of great importance since it can cleave the main backbone of xylan by catalyzing the hydrolysis of B-1,4 glycosidic linkages in xylan

Cellulases are multienzyme complexes with 03 different major components, namely endo-1,4-B-D-glucanase (EC 3.2.1.4), exo-glucanase/exo-cellobiohydrolase (EC 3.2.1.91) and B-glucosidase (EC 3.2.1.21) All of these components act synergistically to hydrolyze cellulose completely into glucose Endo-1,4-B-D-glucanase attacks first and randomly to generate reducing and non-reducing ends, which are further cleaved by exo- cellobiohydrolase to release cellobiose Cellobiose is eventually cleaved by B-glucosidase (BGL) into 02 glucose molecules (Kuhad, Gupta, & Singh, 2011) BGL is the limiting factor in overall performance of cellulase complex since it is inhibited by its end-product, i.e glucose To convert insoluble fibers into soluble fibers, the BGLs which are sensitive

to glucose inhibition are desired due to the restricted saccharification Normally, BGLs

of Trichoderma reesei are subject to product inhibition (Singhania, Adsul, Pandey, & Patel, 2017) Hence, cellulase preparations obtained from this fungus could be useful for converting cellulose into soluble fibers

2.1.4 Application of cellulase and xylanase preparations in processing of cereal brans

Xylanase preparations have been applied in the cereal processing industry to improve the product quality (Singh et al., 2015) Endoxylanase preparations are used to solubilize arabinoxylan in rye bran (Figueroa-Espinoza, Poulsen, Borch Sge, Zargahi, & Rouau, 2004) and also wheat bran (O Santala, Lehtinen, Nordlund, Suortti, & Poutanen, 2011; O K Santala, Nordlund, & Poutanen, 2013) Xylanase treatment is employed to

produce feruloyl oligosaccharides by hydrolyzing xylan of wheat bran (Yuan, Wang, & Yao, 2006) Ingelbrecht, Moers, Abécassis, Rouau, and Delcour (2001) prepare pasta from durum semolina with the aid of an endoxylanase Treatment with endoxylanase is reported to lower extrusion pressure and increase the level of soluble fiber (i.e water- extractable arabinoxylans)

Cellulase preparations are commonly applied in processing cellulosic materials Treatment of wheat bran with cellulase preparation is applied to assist the extraction of xylo-ogliosaccharide (Zhao & Dong, 2016) Aktas-Akyildiz et al (2017) report that processing wheat bran with Cellulast 1.5L (a cellulase preparation) increases the soluble fiber content of bran In addition, the supplementation with enzyme-treated wheat bran significantly improves the soluble fiber content of bread samples Similarly, Vien and Le (2018) conclude that the cookie samples incorporated with cellulase-treated wheat bran exhibited higher soluble fiber content compared to those containing untreated bran These authors also establish the appropriate condition for the treatment of wheat bran with Viscozyme Cassava C (a commercial cellulase preparation) to transform insoluble fibers into soluble fibers, in which soluble fiber content increases by 38% and IDF/SDF ratio is reduced by 74%

2.2 Pasta with high fiber content

2.2.1 Technology of making pasta with high fiber content

The conventional pasta made from durum wheat semolina has a low dietary fiber content, which is 1.2 g/100 g The Codex Alimentarius (2009) recommends that any products claiming to be a “source” of fiber should contain at least 3 g of fiber per 100 g

of serving or 1.5 g of fiber per 100 kcal of serving; while to claim that a food is “high” in fiber, the product must contain at least 6 g of fiber per 100 g of serving or 3 g of fiber per

100 kcal of serving (Foschia et al., 2013) Generally, there are 02 types of materials for manufacture of pasta with improved fiber dietary content This kind of products can be prepared from the durum whole-wheat flour (whole-wheat pasta) or from the mixture of durum semolina and other fiber-rich ingredients (fiber-enriched pasta)

In the simplest production line, the whole-wheat flour or the mixture of semolina and fiber-rich materials are mixed with water to make a crumb-like dough before being kneaded The kneading and forming process can be done either manually or mechanically

by laminators or extruders (Robin & Palzer, 2015) Lamination is used to produce linguini

and square spaghetti while extrusion 1s used to make spaghetti and macaroni The formed dough sheets or extruded strands are then cut into appropriate shapes There are 02 main types of pasta manufactured: the fresh pasta, which is minimally dried or not dried, has a higher moisture content and therefore its shelf life is shorter; whereas the dried pasta has moisture content lower than 12% and has a longer shelf life

2.2.2 Quality of fiber-enriched pasta

The incorporation of fiber-rich ingredients is found to improve the nutritional quality of pasta products The total dietary fiber and protein content of pasta is reported

to be increased when introducing mushroom powders (Lu et al., 2018), deoiled chia flour (Aranibar et al., 2018), or wheat bran (Sobota, Rzedzicki, Zarzycki, & Kuzawinska, 2014) into the formulation The incorporation of some fiber-rich ingredients, namely B-glucan, resistant starch, and oat bran results in a lowered glycemic index of cooked pasta after in vitro digestion (Bustos, Perez, & Leén, 2011; Chillo, Ranawana, & Henry, 2011) In addition, certain fiber preparations are demonstrated to have high antioxidant activity, such as deoiled chia flour, carob fiber, and wheat bran Thus, the inclusion of such fibers into pasta causes an increase in the antioxidant activity of the final product (Aranibar et al., 2018; Aravind, Sissons, Egan, & Fellows, 2012; Biernacka, Dziki, Gawlik-Dziki, Rozyto, & Siastata, 2017)

The incorporation of fibers is reported to affect the cooking quality of pasta, including optimal cooking time, cooking loss, and swelling index Aravind et al (2012) and Sobota et al (2014) figure out that the optimal cooking time is decreased when the level of insoluble fiber increases With regard to the cooking loss, this parameter is raised

as the inclusion level of bran, B-glucan and inulin is elevated (Chillo et al., 2011; Kong

et al., 2012; Tudorica, Kuri, & Brennan, 2002) In terms of swelling index, this value is reported to vary with contrasting patterns in different studies The study of Foschia et al (2013) showed that all of the spaghetti samples fortified with fiber preparations (i.e oat bran, psyllium, B-glucan, and inulin) demonstrate a higher swelling index than that of the sample prepared from semolina only However, other publications report a decrease in the swelling index of pasta and rice noodle at increased enrichment level of durum bran (Aravind et al., 2012) or okra (Kang, Bae, & Lee, 2018)

The effects of fiber enrichment on the textural and sensory quality of pasta are reported in the literature In general, the addition of fiber-rich materials into pasta is found

to negatively impact the texture of final product The texture profile of cooked pasta

enriched with deoiled chia flour, wheat bran, and resistant starch shows a lower firmness compared to that of the sample without fiber (Aranibar et al., 2018; Bustos et al., 2011; Sobota et al., 2014) With respect to the sensory quality, the increase in the incorporation level of fiber generally causes a loss in consumer acceptance of pasta and noodle product (Biernacka et al., 2017; Bustos et al., 2011; B.-R Kim, Kim, Bae, Chang, & Moon, 2017) These findings also reveal that fiber-enriched pasta has a reduced score for appearance, firmness, color, taste, and overall acceptability Moreover, Aravind et al (2012) conclude that pasta samples incorporated with cereal brans exhibit a floury mouthfeel, coupled with

a darker color and rougher surface compared to sample without bran

2.3 Quality improvement of fiber-enriched pasta

2.3.1 Methods for improving textural quality of fiber-enriched pasta

It is known that the formation of starch—gluten network during the mixing and kneading step would determine the textural characteristics of pasta A proper pasta texture should be resistant to stretching and elastic in nature (C S Brennan, 2013) The addition

of fiber may reduce the gluten content and physically disrupt the continuity of the starch— gluten network The weakened and disrupted starch—gluten matrix would exert negative effects on the textural integrity of pasta (Rakhesh, Fellows Christopher, & Sissons, 2014)

At the higher incorporation level of fiber, the gluten content of the dough would be lower and the disruptive impact of fiber on the starch—protein network would be more severe

According to the aforementioned changes, the enhancement in textural quality

of pasta could be accomplished by increasing protein content of the dough and improving the continuity of the starch—protein matrix The augmentation in the protein content of dough could be delivered by the addition of other protein preparations, most importantly vital wheat gluten On the other hand, the formation of new covalent cross-links catalyzed

by transglutaminase enzyme (EC 2.3.2.13) may strengthen the starch—protein network The reformed pasta texture is expected to improve the sensory quality of final product 2.3.2 Improvement in pasta texture by addition of vital wheat gluten

Gluten is commonly found in wheat, rye, and barley It is defined as the protein fraction that is not soluble in water and NaCl 0.5 mol/L Gluten constitutes 80-90% the protein content in flour (Ortolan & Steel, 2017) The gluten is composed of monomeric gliadins (50-55%) and polymeric glutenins (45-50%) The gliadin fraction primely contains single polypeptide chains with MW range of 30,000—75,000 Da The gliadin

chains associate with each other and with glutenins through hydrogen bond and hydrophobic interactions The polymeric glutenins are divided into high molecular weight (MW > 100,000 Da) and low molecular weight subunit (MW ~ 45,000 Da) The high molecular weight subunit of the glutenin fraction is responsible for providing the viscoelastic property of gluten due to the ability to form an intermolecular network Meanwhile, the low molecular weight subunit is crucial for the formation of glutenin macropolymer by intermolecular disulfide bonds (Day, 2011)

Wheat gluten is a common food ingredient, produced by drying wet gluten after being separted from the starch slurry It is marketed into 02 types, “vital” and “nonvital” When in contact with water, vital wheat gluten can hydrate rapidly and restore its original functionality while nonvital wheat gluten does not (Esteller, Pitombo, & Lannes, 2005) Vital wheat gluten is widely used in the bakery industry to improve the crumb structure

of baked product (Ortolan & Steel, 2017) The absence of gluten or reduction in its content may result in the lack of viscoelasticity in dough and therefore difficulty in obtaining the desired product texture and appearance (Moore, Juga, Schober, & Arendt, 2007)

The use of vital wheat gluten in the production of noodle and pasta product from low protein flours is reported in the litterature Raina, Singh, Bawa, and Saxena (2005) figure out at the base flour protein level of 16-18%, noodles prepared from broken rice flour and supplemented with vital gluten show similar texture to commercial semolina pasta The introduction of vital gluten is found to improve the cooking quality, firmness, tensile strength, and overall acceptability of oat noodle (Zhou, Zhu, Shan, Cai, & Corke, 2011) and white salted noodle (Park & Baik, 2009) Nevertheless, the findings of Cuicui, Qiyu, Zipeng, and Huili (2018) reveal that the inclusion of gluten with low disulfide bonds concentration causes an increase in the cooking loss of Chinese white noodle 2.3.3 Improvement in pasta texture by the use of transglutaminase preparation

Transglutaminase preparations have been widely used in dairy, bakery, and meat processing (Kuraishi, Yamazaki, & Susa, 2001) The transglutaminase enzyme (protein- glutamine y-glutamy] transferase) is found in microorganisms, plant, fish, and, mammals

It catalyzes the reaction between an g-amino group in protein-bound lysine residues and

a B-carboxyamide group in protein-bound glutamine residues This reaction leads to the formation of covalent cross-linking of proteins (Yokoyama, Nio, & Kikuchi, 2004) The generation of intermolecular cross-linkings induced by transglutaminase could enhance the rheological properties of the gluten network (Basman, Koksel, & Atli, 2006)

The utilization of transglutaminase preparations in noodle and pasta making is reported in several publications The addition of transglutaminase is found to lower the cooking loss of lupin flour noodle (Bilgicli & Ibanoglu, 2014), oat noodle (Wang, Huang, Kim, Liu, & Tilley, 2011), durum wheat pasta (Krisztina Takacs, Gelencsér, & Kovacs, 2007), and white salted noodle (Wu & Corke, 2005) In contrast, other authors conclude that the increase in transglutaminase dosage causes an elevation in cooking loss (Shiau & Chang, 2013) or does not change the cooking performance of noodle and pasta (Sissons, Aravind, & Fellows, 2010) On the other side, the addition of transglutaminase was found

to improve the water absorption and swelling index of durum pasta (Krisztina Takacs et al., 2007) and and gluten-free noodle (K Takacs, 2007) Treatment with transglutaminase

is reported to successfully enhance the textural quality of conventional pasta (Krisztina Takacs et al., 2007), bran-enriched pasta (Basman et al., 2006) and whole wheat noodle (Niu, Hou, Kindelspire, Krishnan, & Zhao, 2017) Apart from the texture improvement, gluten-free noodle and pasta produced with the aid of transglutaminase also show a lower glycemic index (Gan, Ong, Wong, & Easa, 2009; Rosa-Sibakov et al., 2016)

2.4 Originality of this research

To the best of our knowledge, the effects of adding enzyme-treated wheat bran

on the antioxidant activity and glycemic index of pasta have not been reported in any publications On the other hand, although some studies have used the vital gluten addition and transglutaminase treatment to improve the quality of noodle and pasta product, the effectiveness of both methods combined on quality of bran-enriched pasta is still unknown Our research would deal with the possibility of using vital gluten fornication, treatment with transglutaminase, and combination of gluten—transglutaminase addition to enhance the textural and sensory quality of our high fiber pasta product

3 Materials and Methods

3.1 Materials

3.1.1 Materials for making high fiber pasta

Wheat bran was provided by Binh Dong Milling Factory (Ho Chi Minh City, Vietnam) The proximate composition of wheat bran was as follows: moisture content < 13%, lipid content < 7%, and protein content > 14% The obtained wheat bran was further milled and passed through a 35-mesh (0.5 mm) sieve The processed bran was packaged

in PE (polyethylene) bags and stored at —18°C

Durum wheat semolina was supplied by Vietnam Flour Mills Company (Ba Ria— Vung Tau Province, Vietnam) The proximate composition of durum semolina was as follows: moisture content < 13%, lipid content < 3%, protein content > 12%, and total carbohydrate content > 70% Durum semolina was kept in PE bags and stored at —18°C

Vital wheat gluten was purchased from Roquette (Singapore) The vital gluten preparation has moisture content < 12%, ash content < 1%, protein content > 80%, and gluten index > 38 Gluten index is defined as the percentage of wet gluten remaining on

a standardized sieve after centrifugation (Kaushik, Kumar, Sihag, & Ray, 2015) Gluten preparation was kept in PE bags and stored at 4°C

Table salt was acquired from Southern Salt Group (Ho Chi Minh City, Vietnam) Table salt has moisture content < 1% and sodium chloride content > 99% Table salt was kept in PE bags and stored under ambient condition

Cellulase preparation under the trade name Viscozyme Cassava C was purchased from Novozyme (Denmark) This enzyme preparation is produced by Trichoderma reseii The determined cellulase activity was 233 U/mL One unit (U) of cellulase activity is defined as 1 mol of reducing sugar released from CMC (carboxymethylcellulose) per minute under the assay condition (temperature of 50°C, incubation time of 10 min, and

pH 4.8) (Ghose, 1978) The optimal temperature and pH range of cellulase in this preparation are 45-60°C and 4-6, respectively The enzyme preparation in liquid form was kept in HDPE (high density polyethylene) container and stored at 4°C

Transglutaminase preparation under the trade name Protiact TG-GW was from Rama (Thailand) The determined transglutaminase activity was 109 U/g One unit (U)

of transglutaminase activity is defined as the amount of enzyme that catalyzes the formation of 1 umol hydroxamate per minute from N-carbobenzoxy-L-glutaminylglycine and under the assay condition (temperature of 37°C and pH 6.0) (Ando et al., 1989) The optimal temperature and pH range of transglutaminase in this preparation are 40—55°C and 5-8, respectively The enzyme preparation in powder form was kept in HDPE

container and stored at —18°C

3.1.2 Chemicals

a-Amylase (trade name: Termamy] SC, a-amylase activity: 240 Kilo Novo a- amylase unit/mL), amyloglucosidase (AMG) (trade name: Dextrozyme GA, AMG activity: 270 AMG unit/mL) and protease preparation (trade name: Alcalase 2.5L, protease activity: 2.5 Anson unit/mL) was purchased from Novozyme (Denmark) Pepsin from porcine gastric mucosa (650 unit/mg protein) and pancreatin from porcine pancreas (4 x USP specifications) were acquired from Sigma-Aldrich (Saint Louis, Missouri, United States) Folin—Ciocalteu reagent, 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,4,6- tri(2-pyridyl)-s-triazine (TBTZ), 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), and gallic acid were from Sigma-Aldrich (Saint Louis, Missouri, United States); 3,5-Dinitrosalicylic acid (DNS) and Nessler reagent were obtained from Merck (Darmstadt, Germany) Other chemicals were of analytical grade

3.2 Methods

3.2.1 Procedures

i) Preparation of enzyme-treated pasta

Figure 3.1 shows the procedure for preparation of enzyme-treated wheat bran

11

Figure 3.1 Preparation of enzyme-treated wheat bran

h in a jacketed bioreactor with a U-shaped mixing blade (Model MD9501S, Malayan Daching Co., Singapore) The enzyme solution was slowly added to the wheat bran flour during mixing After incubation, the mixture was heated at 95°C for 5 min for enzyme inactivation

The height of the bran layer was about 1 cm The temperature and relative humidity

of drying air was 50°C and 55-65%, respectively The drying time was about 4 h The final moisture content of dried bran was 10-11%

agglomerated particles The size of each batch was 100 g and the grinding time was

20 s

sieve were recovered and used to produce bran-enriched pasta

2i) Production of bran-enriched pasta

The procedure for making bran-enriched pasta at the laboratory scale is shown

in Figure 3.2

Semolina, bran, table salt

Y Kneading

Vv Extrusion

v Drying

Vv

Bran-enriched pasta

Figure 3.2 Production of bran-enriched pasta Mixing: The raw materials, including durum semolina, wheat bran flour, and table salt were mixed in the mixing bowl In the formulation of bran-enriched pasta, durum semolina was partially substituted by wheat bran (untreated or enzyme-treated) The substitution level of wheat bran varied according to each experiment The content of table salt was 0.5% on the basis of the base flour

Hydration: Distilled water at 42°C was slowly added, combined with mixing at ambient pressure to make a dough This process was performed in a stand mixer (Model SM8005, Ichiban Co., Japan) with a U-shape blade attached The mixing rate was 120 rpm The proportion of distilled water was 32% on the basis of the dough Kneading: The dough was kneaded for 20 min at ambient pressure This process was carried out in a stand mixer (Model SM8005, Ichiban Co., Japan) with a dough hook attached The mixing rate was 120 rpm

Extrusion: The kneaded dough was fed to an extruder (Model HR2365/05, Philip Co., Netherlands) to form pasta strands The extrusion pressure was 720 kgf/cm?

13

The diameter of the extrusion die was 1.6 mm The pasta strands with 50 cm length were cut and hang on metallic sticks

temperature and relative humidity of the drying air were 50°C and 55-65%, respectively The final moisture content of dried pasta was 10-12%

For the evaluation of cooking qualities, dried pasta strands were broken into pieces

of 5 cm in length prior to storage

3i) Preparation of gluten-fortified pasta

The procedure for making gluten-fortified pasta at the laboratory scale is shown

Semolina, bran,

table salt, gluten

in Figure 3.3

Figure 3.3 Production of gluten-fortified pasta The raw materials, including durum semolina, enzyme-treated wheat bran flour, table salt, and vital gluten preparation were mixed in the mixing bowl The content of

table salt was 0.5% on the basis of base flour Distilled water at 42°C was slowly added

to the base flour, combined with mixing to hydrate the ingredients The proportion of distilled water was 32% on the basis of the dough The remaining steps were performed

as described in section 3.1.1.2i1 with the same technological parameters

4i) Preparation of transglutaminase-treated pasta

The procedure for making transglutaminase-treated pasta at the laboratory scale

Semolina, bran, table salt

Vv

Incubation

Vv Extrusion

Ỳ Drying

The raw materials, including durum semolina, enzyme-treated wheat bran flour,

and table salt were mixed in a mixing bowl The content of table salt was 0.5% on the basis of base flour Transglutaminase preparation in powder form was dissolved in distilled water at 42°C The enzyme solution was slowly added, combined with mixing to

15

form a dough The proportion of distilled water was 32% on the basis of the dough The dough was kneaded for 20 min at ambient pressure, then covered in plastic wrap and incubated at 40°C for 10 min The remaining steps were performed as described in section 3.1.1.21 with the same technological parameters

Si) Combination of vital gluten addition and transglutaminase treatment in pasta making

In this procedure, all of the raw materials (i.e durum semolina, enzyme-treated wheat bran flour, vital gluten, and table salt) were initially mixed The content of table salt was 0.5% on the basis of base flour Transglutaminase preparation in powder form was dissolved in distilled water at 42°C The enzyme solution was slowly added, combined with mixing to form a dough The proportion of distilled water was 32% on the basis of the dough The remaining stages were performed as previously described in section 3.1.1.41 with the same technological parameters

3.2.2 Experimental design

The experimental design of the research is summarized in Figure 3.5

Changes in pasta qualities:

® antioxidant activity (total phenolic content, DPPH inhibition activity and FRAP)

@ predicted glycemic index

1 Investigating the effects of

adding untreated and treated

wheat bran on pasta qualities

Changes in pasta qualities:

transglutaminase treatment on "| © cooking quali ty © sensory quality

y

Figure 3.5 Experimental design

i) Investigating the effect of adding untreated and treated bran on pasta qualities

Output:

2i) Investigating the effect of gluten fortification on pasta qualities

Output:

dietary fiber (TDF, IDF and SDF)

index, and water absorption index

e Color: a*, b* and L* parameters

cohesiveness, gumminess, chewiness, tensile strength, and elongation rate

3i) Investigating the effect of transglutaminase treatment on pasta qualities

Varied parameter: The dosages of transglutaminase were 0, 0.25, 0.50 and 0.75 U/g gluten

Fixed parameters:

17

Salt and water content in pasta formulation

Kneading, extrusion and drying condition

Antioxidant properties: total phenolic content, DPPH and FRAP assays

Color: a*, b* and L* parameters

Texture profile of cooked pasta: firmness, gumminess, chewiness, adhesiveness, springiness, cohesiveness, tensile strength, and elongation rate

Sensory quality of cooked pasta: overall acceptability

4i) Investigating the effect of gluten fortification combined with transglutaminase treatment on pasta qualities

“+ Fixed parameters:

Replacement level of enzyme-treated wheat bran flour: 20%

Fortification level of gluten: 5%

Dosage of transglutaminase: 0.25 U/g gluten

Salt and water content in pasta formulation

Kneading, extrusion and drying condition

Antioxidant properties: total phenolic content, DPPH and FRAP assays

Color: a*, b* and L* parameters

Texture profile of cooked pasta: firmness, gumminess, chewiness, adhesiveness, springiness, cohesiveness, tensile strength, and elongation rate

Sensory quality of cooked pasta: overall acceptability

The description of dough formulation and transglutaminase (TG) dosage used in pasta making is summarized in Table 3.1

Table 3.1 Dough formulation and transglutaminase (TG) dosage used in pasta making

& Sugahara, 2008) The total lipid content was determined by a Soxhlet extraction method The ash content was determined by incineration at 600°C The IDF and SDF content was determined according to Method 991.42 and 993.19 (AOAC, 2000), respectively The total starch content was quantified by Method 996.11 (AOAC, 2000) The gluten content of durum semolina was determined according to the method of Kaushik et al (2015)

2i) Cooking quality

Frozen pasta was defrosted for 20 min at room temperature prior to evaluation

of cooking quality About 5 g of raw pasta is cooked in 50 mL of boiling distilled water The water level was kept at a constant level during the entire cooking period by continuously supplying the boiling water The optimal cooking time (OCT) of pasta is determined as the time when the white central core of the pasta disappeared after cross- cutting it with a razor blade (Aravind et al., 2012) To determine the cooking loss and swelling index, pasta samples are cooked to OCT The cooking water is collected from each sample and evaporated to constant weight at 105 °C in a convection dryer Cooking loss is calculated as the percentage of residual solid weight to raw pasta weight (Aravind

et al., 2012) After cooking and draining, the pasta samples were analyzed for water

19

absorption index and swelling index Water absorption index (WAI) was measured as

in a convection dryer and calculated as follows:

SI= weight of cooked pasta — weight of pasta after drying

weight of pasta after drying Five measurements of cooking quality in terms of cooking loss, WAI and SI were performed each pasta sample

3i) In vitro digestion

In vitro digestion of cooked pasta was done following the method of M A Brennan, Merts, Monro, Woolnough, and Brennan (2008) and Chillo et al (2011) with slight modifications Frozen pasta was defrosted at room temperature, cooked to OCT, and cut into pieces of 2-5 mm (Foschia, Peressini, Sensidoni, Brennan, & Brennan, 2015) About 2 g of cooked and sliced pasta were mixed with 30 mL of distilled water and 0.8

mL of HCl 1M to achieve a pH of 2.5 After incubating at 37°C for 10 min in a water bath, pepsin (1 mL of a 10% w/v solution in 0.05 M of aqueous HCl) was added and the incubation was maintained for a further 30 min at 37°C The pH was subsequently adjusted to 6.9 by adding 1 mL of NaHCO; IM, then 0.1 mL of amyloglucosidase and 5

mL of pancreatin (2.5% w/v solution in phosphate saline buffer, pH 6.9) were added The total volume was adjusted to 50 mL with phosphate saline buffer pH 6.9 and incubated at 37°C with slow and constant mixing During the incubation, 1 mL of aliquot was withdrawn at 0, 30, 60, 90, 120, 150, and 180 min and then transferred into tubes containing 4 mL of absolute ethanol These were stored at —18°C for analysis of reducing sugars using the spectrophotometric method with DNS reagent Before the analysis, the contents of the tubes were centrifuged at 3,000xg for 10 min to recover the supernatants

A calibration curve employing D-glucose was constructed The absorbance was read at

540 nm (CT-2300 Spectrophotometer, E-Chrom Tech, Taiwan) The amount of reducing sugars (expressed as glucose equivalent) was converted into the amount of hydrolyzed starch by multiplying by 0.9

A non-linear model established by Goñi et al (1997) was applied to describe the kinetics of starch hydrolysis The pseudo-first-order equation has the following formula:

C=Œ„(I-e*“)

where C corresponds to the percentage of hydrolyzed starch at time t; Cw corresponds to the equilibrium percentage of hydrolyzed starch after 180 min; k is the kinetic constant and tis the time Non-linear regression was performed in ORIGIN PRO 8 to estimate the

parameters

The rate of starch digestion was expressed as the percentage of hydrolyzed starch

to the initial starch content at different time points (30, 60, 90, 120, 150 and 180 min) The area under the starch hydrolysis curve (AUC) was determined according to Hur, Lim, Decker, and McClements (2011):

AUC =C, (t, ~h))+<2|1-e ty

where f= 180 min and f& = 0

The hydrolysis index (HI) was obtained by dividing the AUC of each sample by the AUC

of the reference sample (fresh white bread)

HI= AUC of sample x100

AUC of reference

The predicted glycemic index (pGI) was determined according to Ren et al (2016):

pGI = 39.71 + 0.059HI 4i) Antioxidant properties

e Extractions of antioxidants compounds

The extraction of antioxidant compounds were done as previously described by Biney and Beta (2014) with slight modifications To 1 g of sample, 10 mL of acidified methanol (concentrated HCl : methanol : water, 1:80:20) was added in 15 mL centrifuge tubes, vortexed and shaken at room temperature for 2 h The mixture was then centrifuged for 15 min at 4000 rpm The supernatant was collected and used for the total phenolic content, DPPH radical inhibition and ferric reducing ability (FRAP) assay

e Determination of total phenolic content

The Folin—Ciocalteau method adapted by Beta, Nam, Dexter, and Sapirstein (2005) was used A portion of extract (0.2 mL) was added to 1.5 mL of a 10-fold freshly diluted Folin—Ciocalteau reagent After vortexing, the mixture was allowed to equilibrate

21

for 5 min, after which 1.5 mL of sodium carbonate solution (60 g/L) was added, combined with further vortexing The reaction was allowed to progress at room temperature and away from light for 90 min The absorbance was read at 725 nm Acidified methanol was used as blank A standard curve of versus absorbance was constructed using gallic acid The results were expressed as mg equivalent of gallic acid/100 g dry matter

e Determination of DPPH radical scavenging activity

Antioxidant activity was measured according to the method of Biney and Beta (2014) The method involves the use of the free radical 2,2-diphenyl-l-picrylhydrazyl (DPPH), where antioxidants were allowed to react with the stable radical in a methanol solution The discoloration of the DPPH radicals was followed by monitoring the decrease

in its absorbance at a characteristic wavelength during the reaction The extract (0.1 mL) was reacted with 3.9 mL of a 60 umol/L of DPPH solution (2.4 mg of DPPH in 100 mL

of methanol) The absorbance (A) at 515 nm was read at 0 and 30 min Methanol was the blank Antioxidant activity was calculated as percentage of discoloration Peiscotoration:

A standard curve of different Trolox concentrations versus activity was constructed and results were expressed as pmol equivalent of Trolox/100 g dry matter

e Determination of reducing power (FRAP)

FRAP assay was performed according to Benzie and Strain (1996) with slight modifications In brief, the fresh working solution was prepared by mixing acetate buffer

pH 3.6 with a 10 mM TPTZ solution in 40 mM HC] and a 20 mM FeC]3.6H20 solution (10:1:1, respectively) 20 uL of sample were added to 3.8 mL of FRAP working solution The mixture was then incubated in the dark for 15 min, and the absorbance was measured

at 593 nm The results were expressed as umol equivalent of Trolox/100 g dry matter 5i) Color measurement

The color parameters of pasta (uncooked and cooked) were measured by Konica Minolta CR400 chroma meter (Osaka, Japan) using the CIELAB color space The results were expressed as L*, a*, and b* values L* value represents the lightness (0: darkest black, 100: brightest white), a* value describes the redness (positive) and greenness (negative), and b* value describes the yellowness (positive) and blueness (negative) Color parameters were read at different locations along the pasta strand The chroma C and hue angle h were calculated as follows:

AE.= (1y—E) +(sš =a } +(I; =b')

where Ï2,đa, bạ correspond to the values of the pasta without bran (100% semolina); while

L’,a’,b correspond to the values of the examined pasta sample

6i) Texture profile

All samples were cooked to optimal cooking time on the day of determination

A texture analyzer (Stable Micro System TA-XT plus, United Kingdom) equipped with

a Windows version of the Exponent Connect Lite software package was used to conduct the texture analysis The determined textural parameters were pasta firmness, springiness, cohesiveness, gumminess, tensile strength and elongation rate

In the Texture Profile Analysis (TPA), the probe compressed the samples at a speed of 1 mm/s to 30% strain The probe was subsequently retracted and followed by a second compression cycle after 1 s The results (springiness, cohesiveness, chewiness and gumminess) were recorded

In the tensile strength, 01 strand of cooked pasta was fixed to the arms of tensile grips The force (tensile strength) at the break point was measured at a speed of 1 mm/s The diameter of cooked pasta was determined to calculate the cross-sectional area The tensile strength 7S and elongation rate ER were as follows:

TS=FI/A where F is the force at the break point and A is the cross-sectional area of cooked pasta strand Elongation rate ER is calculated as follows:

ER = (L; — Lz) / La x 100%

where L; is the stretch distance and L> is the set distance

7i) Sensory evaluation

The overall acceptability of cooked pasta was assessed by 60 untrained panelists, aged from 18 to 25 The panelists were recruited from Ho Chi Minh City University of Technology, Vietnam They were asked to consume the cooked pasta and then rate their

23

overall acceptability on a nine-point hedonic scale The time for delivery of cooked pasta samples to the panelists was within 5 min

3.3 Statistical analysis

All of the measurements were done in triplicate The results in this study were expressed as mean + standard deviation One-way analysis of variance (ANOVA) and Turkey’s comparison test with significance level set at p < 0.05 were performed by using Minitab 17 software (Minitab Inc., United States)

4 Results and Discussion

4.1 Proximate composition, color, and antioxidant activity of raw materials

4.1.1 Proximate composition of raw materials

The proximate composition of raw materials is shown in Table 4.1

Table 4.1 Proximate composition of raw materials

Raw material semolina wheat bran wheat bran preparation

Values that do not share a lowercase letter within a row are significantly different (p < 0.05)

It is evident that both enzyme-treated and enzyme-treated wheat bran showed a remarkably higher protein, ash and total dietary fiber content in comparison with durum semolina This suggests that the incorporation of wheat bran into the conventional flour formulation can improve the nutritional quality of pasta The amino acid profile of wheat bran protein is of higher quality than that of endosperm (Balandran-Quintana, Mercado- Ruiz, & Mendoza-Wilson, 2015) In addition, the minerals found in wheat bran are mainly

Fe, Zn, Mn, Mg and P (Onipe et al., 2015) On the other hand, durum semolina and gluten preparation had the highest starch and protein content, respectively

It should be noted that the cellulase treatment did not change the composition of wheat bran, except for the dietary fiber content After the enzymatic treatment, the soluble fiber content of wheat bran was increased by 14.5%, while the insoluble fiber content was decreased by 23.3% The IDF/SDF ratio of enzyme-treated wheat bran was 30.6% lower than that of untreated one The augmentation in soluble fiber content could be due to conversion of cellulose into soluble fragments by the action of cellulase The enzymatic hydrolysis also caused a slight reduction in the total fiber content of wheat bran This was probably due to generation of low molecular weight carbohydrates (LMWCs) In the determination of soluble fiber content, these LMWCs are hardly precipitated in 78%

25

ethanol aqueous solution (McCleary et al., 2012) They could not be recovered and that results in the loss of total dietary fiber content

4.1.2 Color parameters of raw materials

Table 4.2 depicts the color parameters of raw materials

Table 4.2 Color parameters of raw materials

Values that do not share a lowercase letter within a row are significantly different (p < 0.05)

As can be seen from Table 4.2, durum semolina showed the highest L* value (lightness), followed by gluten preparation, untreated wheat bran and enzyme-treated wheat bran In contrast, the a* value (redness) of semolina was found to be the lowest, while the highest redness was attributed to enzyme-treated wheat bran The b*, C, and h value of semolina were generally lower than those of wheat bran and gluten preparation

It is noticeable that processing wheat bran with cellulase resulted in a 9.8% reduction in lightness and a 70.0% increase in redness The slightly darkened appearance of wheat bran could be explained by the formation and accumulation of Maillard reaction products during the enzymatic treatment procedure

4.1.3 Antioxidant activity of raw materials

The antioxidant activity of raw materials is shown in Table 4.3

Table 4.3 Antioxidant activity of raw materials

wheat bran wheat bran

ne GAENIO0 sảm) 105.245.8° 332249.7% — 3564+1222

Qrmol TE/I00 2 im 159.748.0° 12201+653° 1500.3 + 55.6"

“an TE00e ten 182+14° — 821+19 854.1 + 15.9

Values that do not share a lowercase letter within a row are significantly different (p < 0.05)

The total phenolic content (TPC), DPPH antiradical activity and ferric reducing ability of the untreated wheat bran were 3.2, 7.6 and 45.1 times higher than those of the

durum semolina, respectively It is reported that majority of antioxidants in wheat grain are the phenolic compounds located in the bran layer (Yu, Nanguet, & Beta, 2013) The TPC and ferric reducing power of both untreated and cellulase-treated wheat bran were not statistically significant (p < 0.05) L Liu et al (2017) report that a complex enzymatic hydrolysis employing a-amylase, glucoamylase, protease, and cellulase significantly increases the bioavailability of the antioxidative phenolics in rice brans In cereal brans, most of the phenolic compounds are conjugated with the cell wall components (Calinoiu

& Vodnar, 2018) Hence, the release of those phenolics required a combination of several enzymatic treatments

Additionally, the cellulase treatment led to a 18.7% increase in DPPH inhibition activity of wheat bran A partial explanation to this phenomenon could be the formation and accumulation of Maillard reaction products during the incubation with enzyme and drying process of treated bran The Maillard reaction generally involves the interaction between amino acids and reducing sugars or lipid oxidation products (Yilmaz & Toledo, 2005) The products derived from Maillard reaction were demonstrated to have various extents of in vitro radical scavenging activity (Nooshkam, Varidi, & Bashash, 2019) 4.2 Effects of wheat bran incorporation on the qualities of pasta

4.2.1 Antioxidant activity

The antioxidant activity of uncooked pasta samples is shown in Table 4.4

27

Table 4.4 Antioxidant activity of uncooked pasta samples

Sample code Pasta incorporated with untreated wheat bran Pasta incorporated with enzyme-treated wheat bran

Total phenolic content = ing ayo A> (mg GAE/100g d.m.) 113.944.5345 139,544.44 156.245.9% 108.442.14% 123.543.64 1468460 1633+6.8^^

(umol TE/100 g dm.)

(umol TE/100 g d.m.)

Values that do not share a lowercase letter within a row are significantly different (p < 0.05)

Values that do not share an uppercase letter within a same level of bran are significantly different (p < 0.05)

28