(Luận văn thạc sĩ) research on the production process of candied orange slices product

Candied orange slices is a product made from thinly sliced fresh orange, reduced the bitterness of the skin, and refine with sugar with a moderate sweetness, supplemented with honey to h

THAI NGUYEN UNIVERSITY OF AGRICULTURE AND FORESTRY

ADVANCED EDUCATION PROGRAM

: MSc NGUYEN ĐUC TUAN

ACKNOWLEDGEMENT

First of all, I am grateful to the Thai Nguyen University of Agriculture and

Forestry, the Advance Education Program, the Faculty of Biotechnology and Food

Technology, where have taught and imparted necessary knowledge and valuable

experience to me, during the time I studied and researched at Thai Nguyen University

of Agriculture and Forestry

I really want to show my deeply grateful to my supervisor Mr Nguyen Duc Tuan

for his conscientious contribution and useful suggestions during the planning and

development of my research work His precious critiques helping me to understand

how to complete my graduation thesis Once again I sincerely thank my supervisor and

wishing good health for him

I am also thankful to Ms Le Thi Thu Hien, Ms Nguyen Thi Tra, Mr Le Sy Luy,

and Ms Chu Thi Nhan who willing to give me a hand when I do the thesis in the

Laboratory of Faculty of Biotechnology and Food Technology

I also acknowledge with a deep sense of reverence with all members of my

family who are always to help and encourage me on the completion of this thesis

I also would like to thank all of my friends who directly or indirectly helped me

to complete this thesis

However, due to the limited knowledge and the lack of practical experience, the

content of the thesis cannot avoid shortcomings, I would like to receive further

suggestions and advice to make my this thesis is more complete

PART 1 INTRODUCTION

1.1 Research rationale

Vegetables and fruits are indispensable foods in the human diet They provide essential nutrients for the growth of the body and strengthen the immune system, prevent diseases such as cardiovascular disease, blood pressure, stroke, etc [1], [32] Fruits and vegetables also play an important role in human nutrition and health, such

as sources of vitamin C, vitamin B1, vitamin B3, vitamin B6, vitamin B9, minerals, dietary fiber (Wargovich, 2000) In Vietnam, fruits and vegetables are a source of food for the human, and economic source of the farmer, helping to create jobs, and at the same time developing Vietnam's economy Currently, Vietnam has exported fruits and vegetables to more than 60 countries around the world, according to the General Department of Vietnam Customs, by mid-March 2017, Vietnam's export turnover of fruits and vegetables reached nearly $ 543 million, increased by 26.7% over the same period last year [139]

The climate of Vietnam is located in the tropical monsoon region with 4 distinct seasons: Spring, Summer, Autumn, and Winter, the weather of Vietnam is also divided into two seasons, rainy and dry Therefore, Vietnam is suitable for many types of fruit trees vary depending on regions such as litchi, jackfruit, avocado, oranges, tangerines, apples, durian, etc In which, oranges grow into specialized areas such as Tuyen Quang, Bac Giang, Ha Giang, Hanoi, Hung Yen, Vinh, Nghe An, etc Oranges content many benefits to the human body such as a rich source of vitamin C, fiber, low in calories, boosting cardiovascular health, However, fresh oranges are very roots damaged during transportation and storage due to physiological activities, biochemistry, and microorganisms, etc Normally, the rate of post-harvest loss in oranges is relatively large from 15-30% and this rate also increases during distribution and storage processing In this situation, the application of post-harvest processing techniques to reduce the loss of quality of raw materials is essential in Viet Nam [24], [717]

Today, on the market there are many types of products made from oranges that are trusted, such as orange candy, orange juice, orange syrup, orange jam, etc However, candied orange slices are a product that has not yet been studied and deeply researched due to the difficulty of the production process from the processing of raw materials to stages of bitter elimination and product completion Candied orange slices

is a product made from thinly sliced fresh orange, reduced the bitterness of the skin, and refine with sugar with a moderate sweetness, supplemented with honey to help perfect the product flavor that ensures health safety for humans Processing of candied orange slices is one of the basic measures to preserve fruits, helping to extend the storage time up to 1 year compared to fresh fruit, giving a completely different product than the raw material However, in the world, dried fruit jam is applied in production and trade with materials such as pineapple, bananas, apples, ginger, But the products

of candied orange slice have very little on the market, there is no specific research on the production of this product according to the production scale

The purpose of this study is to process candied orange slices from some types of orange in Vietnam with good nutritional value and good sensory value, contributing to diversifying to these products on the market and increasing income for orange growers Stemming from the above-mentioned reality, I implemented the thesis:

“Research on the production process of candied orange slices” at the laboratory of

The faculty of Biotechnology and Food Technology

- To determine the effects of the bitter elimination method on product quality

- To determine the ratio of mixing orange and sugar on product quality

- To determine the effects of temperature and drying time on product quality

- Evaluate the quality of the product candied orange slices finished product

- Establish a process for processing the product's candied orange slices

1.3 Research questions and hypotheses

1.3.1 Research questions

- Do we use salt water to remove all bitter taste of orange peel?

- Can we use other types of sugar add-in? what are other types of sugar?

- What is the effect of honey on the final product?

- What is the appropriate drying temperature?

1.3.2 Research hypotheses

- If we use 5% salt water, then candied orange slices will be de-bitter

- If we choose the ratio of oranges and sugar is 2:1, then the candied orange slices product will have a pertinent sweet taste

- If choosing the temperature for drying is 55oC in 24h, then the product will be safe humidity

PART 2 LITERATURE REVIEW

2.1 The scientific basis of the thesis

2.1.1 The origin of orange

Oranges with the scientific name are Citrus sinensis belongs to the citrus family

Oranges vary in size depending on the variety and type Ripe oranges have a sweet and slightly sour taste [85]

There are many different origins regarding the origin of citrus, Orange trees have been around for as long as 2200 BC in China, but some argue that oranges are native

to the Himalayas (India) Oranges are very popular in India, then spread to east and southeast Asia Around the 3rd century BC, orange trees were brought to Europe and spread to the Mediterranean regions The orange tree was then brought to America by Columbus In the following years, growers in the Americas brought orange trees to Australinea and Africa Today orange trees are grown very popular in many countries

2.5 Orange flowers: Oranges often bloom in the spring Each time there are often lots of flowers, but only a small number develop fruit Orange flowers are usually white, small, clustered, with a light, pleasant aroma [85]

- Orange roots: Like woody plants, the roots are absorbed water and mineral salts The root system is shallow, broad, and dense, distributed in topsoil and porous soils The root system grows most strongly in February and September and thrives in the first 8 years [1713]

- The oranges fruits are spherical, with a thin rind, orange-yellow when ripe, sweet, or slightly acidic [20]

Some varieties of oranges are grown in Vietnam:

+ Vinh orange is the name of a fruit of the citrus genus, which is geographically associated with the place name Vinh (Nghe An, Vietnam) Vinh oranges are round, succulent, yellow evenly The orange color of Vinh orange is bright yellow lemon mixed with green color There are many varieties of oranges nowadays: Xa Doai orange, Van Du orange, Song Con orange, Navel orange, etc [85]

• Xa Doai orange (Citrus sinensis 'XA DOAI') is a crop of oranges of Spanish

origin grown in Vietnam The fruit has two forms, the high fruit and the oval (the fruit are flat) Fruit diameter average 6.8-7.8 cm, the average weight of 200-250gram / fruit, usually with 10-12 pieces, lots of water, 2-3cm thick pods, when ripe, the color peel is bright yellow [85]

Figure 2.2 Xa Doai orange

• Song Con oranges imported by a French plantation owner planted on Dao Nguyen production hill (today's Song Con Farm) should be named "Song Con oranges"

The fruit is very thin skin, lots of water but sweet and also very fragrant Song Con oranges after 3-4 years are the beginning of harvesting, high productivity, good tolerance to pests and diseases, very suitable for many mountainous midland areas

• Van Du orange: It is an orange imported to Van Du orange farm in 1947, through a good selection process, create to orange type with good quality From here take the breed to other places with name is "Van Du orange" This is a strong, broad canopy tree with large, dark green leaves This orange variety produces medium-sized fruits, lots of water but it contains many seeds The taste of this orange is also special, darkly sweet and slightly bitter taste dissolves quickly after eating

• Navel orange: Also known as umbilical oranges: Native products in California

(USA), planted in Vietnam in 1937, are still scattered in farms The average fruit is 230g / fruit, can reach 290g / fruit, a diameter of approximately 7.6 cm, when ripe fruit

is yellowish gray There are 11 to 12 sections of oranges with dark yellow fruits

Figure 2.3 Navel orange

• Hai Duong orange: Growing much in Thanh Ha, Tu Ky (Hai Duong) should be called Thanh Ha orange, Dong Dinh orange Large fruits (600 - 700g / fruit) on average also weigh from 300 - 400g / fruit, 10cm diameter fruit, the skin of the red-yellow fruit The orange cloves are white color, the seeds big and flat with 20-30 seeds/fruit, sour, bitter taste

+ Sanh orange (C reticulata x C Sinensis: king mandarin)

We can easily recognize by its thick skin fruit, which is typically bright green Its flesh is orange, dark, and sweet This is the most popular orange variety in Vietnam Its flesh is orange, dark, and sweet The most popular orange variety in Vietnam is Sanh orange

Typical of king mandarin: Bo Ha oranges, Ha Giang, Tuyen Quang, Yen Bai,

Bo Ha oranges are grown in Bo Ha, Yen The district, Bac Giang province Bo Ha orange is suitable with mountainous midland, cool and humid climate

Ha Giang - Tuyen Quang - Yen Bai oranges: are an orange region mainly in the northern provinces of Vietnam with high productivity, the fruits are harvested on Tet holiday In Tuyen Quang province, the most famous is Ham Yen orange, this is a region with delicious oranges

Figure 2.4 Sanh orange

+ Sweet orange (Citrus sinensis L.Osbeck)

The average fruit weighs about 100g, the skin is thin, yellow red or dark red, easy

to peel, easy to divide There are three main types of oranges: Canh orange (Hanoi), Dong Du oranges (Hai Phong), Ngoc Cuc and Hanh Thien oranges (Nam Ha); Bu orange, Sour orange, easily planted, slightly sour taste, common in Huong Son (Ha Tinh), Tuyen Hoa (Quang Binh); Voi oranges (big orange) with big fruits of 300 - 350g, hybrid of Bu and grapefruit, planted in Tuyen Hoa (Quang Binh)

Figure 2.5 Sweet orange

2.1.2 Characteristics of orange fruit

The composition of an orange consists of the following:

The outermost layer (flavedo): orange or blue depending on the breed The outermost layer is the layer that contains many essential oil sacs, therefore having a strong flavor similar to that of the orange pulp [1713], [20]

The white part of the rind (albedo): contains pectin and cellulose, has nearly the same amount of vitamin C as the flesh and other nutrients [139], [20]

Carpels with juicy vesicles: the inside contains, the orange cloves are cell fluids

A section of an orange: in it cure the orange cloves and the cell fluid

Orange seeds: hold sprout, include endosperm, embryo, seed coat [96]

Central column: The part located in the center of the orange, containing pectin and cellulose[96]

Table 2.1 Physical parameter of a sweet orange fruit [26]

9 The thickness of flavedo (mm) 1.8

The compositions of orange

Citrus is a valuable fruit tree on the international market, being one of the most traded fruits Moreover, this is a fruit with high nutritional value

Table 2.2 The nutritional composition of fresh orange (USDA) [33]

Nutritional composition of orange per 100 gram

Nutritional composition of orange per 100 gram

Oranges also contain a lot of fiber, mainly pectin, cellulose, hemicellulose, lignin The daily supplement of fiber is very beneficial to health, especially improving the function of the digestive system and nourishing beneficial bacteria (Metabolic Benefits

of Dietary Prebiotics in Human of National Institutes of Health) Orange is rich in vitamins and minerals, especially vitamin C, thiamin, folic acid, and potassium Eating oranges regularly will help our body be healthier Oranges are rich in flavonoids, especially hesperidin, which helps prevent heart disease effectively (Hesperidin Contributes to the Vascular Protective Effects of Orange Juice by National Institutes of Health) Research has also found that drinking lots of orange juice will

have significant blood thinning and blood pressure reduction (Both Red and Blond Orange Juice Intake Decreases the Procoagulant Activity of Whole Blood in Healthy Volunteers by National Institutes of Health) Iron deficiency is the leading cause of anemia, which means a decrease in the number of red blood cells or hemoglobin in the blood Although oranges do not contain an abundance of iron, they are rich in vitamin

C, citric acid, etc, which enhances the absorption of iron from the digestive tract Therefore combining daily oranges supplements will help to prevent anemia [34]

The chemical composition of orange peel

Cellulose is a polymeric polysaccharide that has no sugar properties and is a major component of plant cells Cellulose is insoluble in water, water inflates a portion

of cellulose It absorbs water with 7-8% by weight

Hesperidin C28H34O5 is abundant in citrus peels, has no bitter taste, has vitamin P activity

Naringin C27H32O14, both in the skin and in the citrus juices, when the fruit is green, naringin causes a bitter taste

Table 2.3 Summary of the composition, percentage, nutritional value, and

pharmacological effects of each orange composition

Seeds 1-2 Hemostasis can be used in medicine

Vietnam standard for oranges

According to TCVN 1873:2014, we have the following requirements for the

quality of the oranges to produce candied orange slices as follows:

- Intactness

- Not crushed or damaged to the extent that it is unsuitable for use;

- Clean, virtually no foreign matter visible to the naked eye;

- Almost no insects that affect the appearance of the product;

- Hardly damaged by the pest;

-Do not experience abnormal moisture outside the enclosure, unless condensed due to release from the cold storage environment;

- Without any strange smell and / or taste;

- Not damaged by low temperatures and / or high temperatures;

- Not damaged by frost;

- There is no sign of dry porosity inside;

- Virtually no bruises and / or many healed cuts;

- Fresh oranges must achieve appropriate growth and maturity

The technical requirements of the sugar are as follows (TCVN 6959: 2001):

Table 2.4 Sensory indicators of sugar

Texture White crystals, relatively uniform in size, dry, no lumps

Taste Sugar crystals or sugar solution in water has a sweet taste, no

strange smell

Color

White crystals When diluted

sugar in distilled water to make

a clear solution

Ivory - white to white crystals When we mixed sugar with distilled water, the solution is relatively clear

2.1.4 Salt (sodium chloride)

Most kinds of jam on the market such as apple jam, strawberry jam, papaya jam,… we do not need to use salt in the production process However, the composition

of orange peel contains flavonoids, pectin, citric acid, creating a bitter taste of oranges Therefore, using natural ingredients and salt will help to reduce the bitter taste of the product as well as safety to consumers' health [23]

According to TCVN 9639:2013, sensory indicators of salt must conform to the requirements specified in the following table:

Table 2.5 Sensory requirements of sodium chloride [518]

1 color White color

2 smell No strange smell

3 taste The solution has 5% of pure salt taste typical of salt, no

Lime water is used quite a lot in food and is considered safe, helping to make the product is crispy, chewy, and clear, creating a perfect taste Although lime water does not affect human health, using the right ratio will create a perfect product

2.1.6 Honey

We know that honey is made up of sweeteners collected by the bees Honey compositions content саrbоhуdrаtе (fructose, glucose, sucrose), water, mineral substance, a nitrogen compound, alkaloids, biological stimulants, plant antibiotics, enzyme, organic acid, essential oil, antioxidant, prevent cancer,…

Because of the sweetness and the characteristic aroma of honey, we have used them in the production of candied orange slices product However, because the price

of honey is quite high, so it is used as an auxiliary material and to increase the quality

of the product Honey used to produce honey must retain the natural, must not mix, and add any ingredients Honey is not heated or processed, because it can cause a change in its composition and quality (TCVN 12605: 2019)

Table 2.6 Sensory requirements of honey (TCVN 12605: 2019)

1 color Honey comes in a variety of colors from almost colorless to dark

brown color

2 smell The characteristic aroma of honey

3 taste From light sweet to strong sweet

4 texture From viscous liquid to crystalline

2.2 The importance of the orange industry to people and the economy

2.2.1 The importance of the orange industry to people

We know that oranges are rich in nutrients such as vitamin C, fiber, folate, antioxidants but very few calories and sugar To encourage us to eat oranges daily to nourish the body

According to M.D Nguyen Thi Hang (Vice Chairman of the Department of Eastern Medicine, Vietnam Academy of Traditional Medicine): Orange juice contains flavonoids that are beneficial to health and is a source of hesperidin antioxidants Orange juice is rich in vitamin C that can help lower blood pressure, the nutrients in orange juice also act as a diuretic, causing the kidneys to excrete more salt and water out of the body to enhance resistance, anti-fatigue [31]

Drinking orange juice with a little salt added after exercising a lot of sweat is a way to regain fitness quickly By the amount of fructose and 85% of the water in the orange will quickly be absorbed by the body, have a refreshing effect, and strengthen the body [34]

Enhance eyesight: Orange is rich in carotenoids and vitamin A These substances help enhance eyesight, especially good for women who have problems with macular degeneration [34]

Anti-cancer: Scientists have recently published the results of the prevent-cancer effects of orange juice It contains flavonoid substances like hesperidin and naringenin

Laboratory studies have shown that orange juice reduces childhood leukemia, as well

as combating breast, liver, and colon cancers [31]

Reducing the risk of cardiovascular disease: Studies have shown that orange juice can help reduce the risk of heart disease because it can help improve blood circulation [34]

Anti-aging for the skin: Oranges are full of beta-carotene which is a powerful antioxidant that protects cells from damage, while also protecting the skin from free radicals and preventing the signs of aging [34]

Weight-loss support: A large orange contains 4 grams of fiber and only 87 calories Therefore, eating oranges helps you to prevent hunger, limit junk food habits

In addition, oranges are also rich in mineral vitamins to help you always feel healthy, full of energy [31]

Preventing virus infection: Consuming foods rich in polyphenols can help you boost your immune system, thus helping to protect you from viral infections Oranges contain lots of polyphenols which is an anti-viral, anti-inflammatory, anti-allergic, anti-carcinogenic and anti-proliferative agent.dustry to people and the economy [34]

2.2.2 The importance of the orange industry to people and the economy

Orange trees prefer tropical climates, strong vitality to easy to cultivate, and care compared to many varieties Currently, the popular varieties of oranges such as gourmet oranges, oranges, etc give a high income to farmers If more techniques to handle off-season flowering are applied to citrus, the selling price will be higher, which will bring a significant source of income for farmers

The domestic and foreign consumption markets are being expanded, thus creating jobs and increasing incomes, improving economic life for farmers, and increasing export turnover, creating a large revenue source It is estimated that with 1.5 ha of land, it is possible to yield over 80 tons/crop

Orange trees have gradually asserted their effectiveness in the economic development of farmers For this model to bring about sustainable efficiency, the functional sector needs to create favorable conditions for farmers to access techniques, find quality seed sources as well as a stable consumption market so that gardeners can rest assured production

2.3 The situation of orange production and consumption in Vietnam and

worldwide

2.3.1 The situation of orange production and consumption in Vietnam

Figure 2.6 Area planted oranges in Vietnam from 2005 to 2018

Based on the chart, we can see that the area of oranges growing from 2013 to

2018 tends to increase, from 75 thousand hectares to more than 120 thousand hectares

in 5 years, which means that Vietnam is gradually investing in growing oranges,

brings high productivity, contributing to the development of the economy

Formatted: Centered, Space After: 0 pt, Line spacing: 1.5

lines, Tab stops: 0 cm, Left + 0.95 cm, Left + 1.27 cm, Left + 3.81 cm, Left

Figure 2.7 Orange production in Vietnam

2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 Production

2016, an increase of 151 thousand tons [35]

Cao Phong District, Hoa Binh Province is one of the places with the largest orange supply in the North of Vietnam According to statistics February 2017, the whole district has 2,080 hectares of citrus fruit In which oranges account for 1,367ha The area of oranges in the business period is over 900ha, the harvested output in 2016

is over 23 million tons, the average price from 25,000 to 35,000 VND / kg This is a great source of income for farmers in Cao Phong district Each year, Cao Phong orange harvest season usually takes place from August to May of the following year, divided into varieties of early maturity, main crop and late ripening [35]

Sanh orange is planned on an area of over 7,000 hectares in 13 communes and towns with over 4,000 households growing oranges; The average annual production is from 80 to 100 thousand tons, the price ranges from 40,000 to 50,000 VND / kg, the annual value is estimated at over 650 billion VND In 2007, Sanh orange was granted

a certificate of product branding and trademark building by the National Office of Intellectual Property It is in the "Top 50 famous Vietnamese specialty fruits", "top 10 famous brands in Vietnam", and the title of "Vietnam Agricultural Gold Brand" [35] Vinh orange is planted in the key orange region of Nghe An in Quy Hop with over 2,000 hectares Average productivity is 27 tons/ha, there are outstanding areas with productivity of over 45 tons/ha/year Each hectare of orange gives growers over

700 million VND [35]

In Vietnam, products are processed from Orange specialties according to the process of ensuring food hygiene and safety Good oranges are utilized from the skin

to the intestines, so avoiding waste in the garden, taking advantage of oranges types 3 and 4, creating additional income for orange growers Products made from oranges have very good health effects such as orange peel jam, orange syrup for coughs, colds, orange essential oil for the steam bath to bring mental refreshment, treat fever, runny nose, beauty skin, can also be used in the processing of baked goods Products such

as orange wine, essential oil, orange jam, etc have enhanced the value of Vietnamese orange brand [35]

2.3.2 The situation of orange production and consumption worldwide

Figure 2.8 Orange production worldwide from 2012/2013 to 2018/2019

(in million metric tons) (M Shahbandeh, 2019)

The chart shows the number of oranges produced worldwide from 2012 to 2019 The amount of oranges has changed markedly, as follows: in 2012/2013 was 49.85 million metric tons, in 2018/2019 increased significant was 54.28 million metric tons

of oranges

Figure 2.9 Leading orange producing countries worldwide in 2018/2019

(in million metric tons) (M Shahbandeh, 2019).

During the marketing year 2018/2019, we can see that Brazil is the largest

producer of oranges in the world, reached 20.16 million metric tons, according to the

figure 2.1, that year, the worldwide produced 54.28 million metric tons, therefore,

Brazil account for about 37% of oranges production worldwide [36]

Following by Food and Agriculture Organization of the United Nations,

Statistical Bulletin, 2016; production of oranges of all countries in the world from

2008 to 2016, in the Northern Hemisphere, countries with a large production of

oranges such as the USA, Mediterranean Region included Italy, Spain, Egypt, Turkey,

Mexico, China, India, Indonesia, Islamic Republic of Iran, Pakistan, in the Southern

Hemisphere have Brazil, South Africa [22], [36]

2.4 Products made from oranges

Orange juice: It has bright colors and a refreshing flavor extracted from fresh

oranges and concentrated fresh orange juice and pasteurized to further retard spoilage

We can use orange juice to adds to drinks, candies and sweets

Orange peel extract is elaborated with orange peel and orange core The product

is the perfect options for beverages, soft drinks, or food applications

Formatted: HÌNH CK, Left, Line spacing: single, Tab stops:

Not at 0 cm + 0.95 cm + 1.27 cm + 3.81 cm

Formatted: Font: Not Bold, Not Italic

Dry orange juice powder, this substance can be used within numerous products A

handful of examples here can include Ready-made meals, jams, and syrups, flavorings,

orange-flavored tea, as an additional ingredient within cookies, icings, and cakes

Orange syrup: Its main uses are soft drinks and beverages, but it can also utilize

in the elaboration of ice creams, dairy products, bakery products, ready meals, jams,

other syrups, etc Orange syrup with a brix level of 41.0-44.0

Orange Essential Oil is completely natural and is obtained from the peel of fruits

of different types of Citrus Sinensis obtain this product through a mechanical process,

using a cold-pressed method and without any thermal treatments And then pack it in

drums just after its extraction to maintain its properties

Jam products:

Fruit jams are products made from fresh or semi-prepared fruits cooked with sugar

to dryness of 65-70% Featured jam products are sweet, naturally pure aroma of berries

In addition to the content of sugar available in the fruit, people also add a large amount

of sugar Fruit jam with high acid content also inhibits the activity of microorganisms

Most fruit jams need a certain amount of coagulation The coagulant available in the

fruit is pectin During storage, jam can be gradually mortar, at first on the face, and

then spread out If stored at low temperatures, the product has a pH below 2.8 and

has many impurities, or is subject to mechanical impact, the jam becomes even more

decompose [139]

Jam classification: according to the state of product structure

• Coagulated jam:

- Processing from juice or fruit pure

- Create gel coagulated with pectin or agar

- There are 3 types: Jelly, Jam, Marmalade

- The dry matter content is about 60-65%

• Flexible drying jam:

- Pieces or whole fruit

- Soft, slightly wet, no more sugar syrup around the product

- The dry matter content is about 70-75%

Formatted: Expanded by 0.1 pt

Formatted: Expanded by 0.1 pt

• Crispy drying jam:

- Pieces or whole fruit

- Outside there is a sugar coat crust

- Dry matter content 75 - 80%

The product "candied orange slice" like Crispy drying jam, with pieces orange connect with sugar and dry at high temperature and create to the product with the dry matter around 90%

2.5 General process of producing candied orange slices

Flow chart 1 General process of producing candied orange slices

Fresh oranges

Washing

Handling

Mixing with sugar

Product

According to the research “Research on greening disease prevention and trial planting of new orange varieties in Ham Yen, Tuyen Quang province, Viet Nam”, we have the general procedure to producing our product Explain the procedure as follows [717], [27], [24]:

2.5.1 Fresh oranges

Raw materials used to produce products must be of good quality, achieve maturity, a state of hardness and no defects, no smashing, meeting the standards of TCVN 1873: 2014

2.5.4 Soaking in lime water

Soaking in lime water helps to increase the firmness of the product and removes some of the bitter substance in the orange peel

Procedure:

- Put the orange pieces into the prepared lime water and soak for 10 hours

- Rinse with clean water after soaking

2.5.5 Mixing with sugar

The effect of sugar added to the product to create a sweet taste, increase the shelf life Orange peels have the effect of increasing the flavor and freezing of the product However, it is necessary to treat orange peel before mixing to reduce the bitterness of the skin, affecting the quality of candied orange slices

Soaking the sugar will help the orange pieces to soak into the sugar, while the melted sugar will avoid localized burning when concentrated

Procedure:

- Put the sugar into orange after draining

- After mixing sugar, let stand for 12 hours for the orange to soak into the sugar and dissolve

Procedure: The drying stage is used by specialized dry ovens

- Set the drying temperature

- Spread the orange pieces after concentrating on the drying tray

- Put the drying tray into the oven

+ Natural cooling: A method to cool after drying in the room and slowly

+ Forced cooling: As a fan-cooling method, this cooling method has advantages over natural cooling which is faster cooling time, the product is less changed

+ Close the door

Fully print product information on the package including product name, net weight, ingredients, production date, expiry date, instructions for use, address of the manufacturer, etc

+ Quantitative: Weigh

+ In the bag: Need to seal the mouth of the bag (PE bag) or tighten the cap tightly (glass and plastic vials)

2.5.10 Preserving candied orange slices

Although products are high in sugar, the storage process does not guarantee water leakage Therefore, it is necessary to conduct cold storage at a temperature of 3 - 7oC

to extend the shelf life of the product On a small scale, the product can be stored in the refrigerator

PART 3 CONTENTS AND METHODS

3.1 Material

3.1.1 Research subjects

- Raw oranges are mainly Chanh Orange and ripened oranges purchased in Thai Nguyen city Raw materials must meet the requirements of specific technical ripeness, the fruit must not be rotten, crushed, and naturally scented, reaching TCVN 1873 - 2014

- Sugar of Thanh Hoa company reaches TCVN 6959:2001, salt of Van Ninh company reaches TCVN 9639:2013

- Lime has been purchased at Thai market - Thai Nguyen City

3.1.2 Research instruments, equipment, and chemicals

Table 3.1 Research instruments and equipment

No Instrument Production

the processing time of products compared to the use of sunlight, besides using a

dehydrator machine can help achieve higher quality products, food safety, and

hygiene

Figure 3.1 Drying oven 3.1.3 The location and duration of research

- Location: Faculty of Biotechnology and Food Technology – Thai Nguyen

University of Agriculture and Forestry

- Duration: From 12/2019 to 7/2020

3.2 Methods

3.2.1 The experimental design

3.2.1.1 Research on choosing the bitter elimination method of fresh orange

Table 3.3 Research on choosing the brine solution to the bitter elimination method

of fresh orange

Formula Salt (ratio salt/water (%) Fixed factor

- Soaking time in lime water: 10h

- Orange /sugar ratio: 2.0:1.0

- Drying temperature: 55ᴼC in 24h

Assessing the structure, flavor, taste, and color of the product, we used the

sensory evaluation method After sensory evaluation, we have the result, and using the

Formatted: Font: Italic Formatted: Font: Not Bold

SPSS software to statistical analyses and selecting the ratio of salt to the water and the time to soak oranges with saltwater is most suitable for processing orange jam products With this experiment, we have the important index value, namely: Color is 0.8, taste 1.2, flavor and structure are 1 Because using salt to remove the bitter taste is the most effect on the taste of the final product, so the important index of taste is the highest value

3.2.1.2 Research on choosing the ratio of orange and sugar to product quality

Table 3.4 Research on choosing the ratio of orange and sugar to product quality

Formula Orange: sugar

(% orange meat) Fixed factor

Formula 1 1.5:1.0 - Soaking time in lime water: 10h

of the final product most If there is too much sugar, the taste is too sweet and the color turns brown after drying, while if there is less sugar the taste will be pale After evaluating and scoring, we will choose the best ratio of orange and sugar to do the next experiments

3.2.1.3 Research on choosing drying temperature on product quality

Table 3.5 Research on choosing drying temperature on product quality

Formula Temperature (ᴼC) Fixed factor

Formula 1 50 - Soaking time in lime water: 10h

- Ratio of salt and water: was selected