TEA, COFFEE, COCOA AND CHOCOLATE PROCESSINGS

MINISTRY OF EDUCATION AND TRAINING NONG LAM UNIVERSITY – HO CHI MINH CITY FACULTY CHEMICAL ENGINEERING AND FOOD TECHNOLOGY  TEA, COFFEE, COCOA AND CHOCOLATE PROCESSINGS GROUP 3 MEMBERS January 20.

MINISTRY OF EDUCATION AND TRAINING NONG LAM UNIVERSITY – HO CHI MINH CITY FACULTY: CHEMICAL ENGINEERING AND FOOD TECHNOLOGY

Đỗ Hồng Ánh Mai

Đỗ Thị Yến Ly

TABLE OF CONTENT

TABLE OF CONTENT 1

INTRODUCTION 2

PART 1: ANTIOXIDANTS IN TEA, COFFEE AND COCOA AND THEIR CHANGES DURING PROCESSING 4

I Antioxidants in tea, coffee, and cocoa 4

1 Tea 4

2 Coffee 10

3 Cocoa 17

II Changes of antioxidants in tea, coffee, cocoa during processing 19

1 Tea 19

2 Coffee 23

3 Cocoa 27

PART 2: FAT IN COCOA – THEIR CONTRIBUTION TO CHOCOLATE PROCESSING 32

I Fat in cocoa 32

II Contribution of cocoa butter to chocolate processing 34

III Some cocoa butter alternatives are used in processing 35

CONCLUSION 39

REFERENCES 41

INTRODUCTION

Antioxidants are substances that can prevent or slow damage to cells caused by free radicals, unstable molecules that the body produces as a reaction to environmental and other pressures Antioxidants counter the development of free radicals within the body They carry out a process called free radical scavenging, which means they come through the body tissues and consume free radicals This means that rejuvenating effects

of correctly roasted coffee doesn’t just come from the caffeine that wakes you up when you’re sleepy By drinking healthy coffee, tea, or cocoa you are restoring your cells and protecting them from the damaging (yet hard-to-avoid) effects of daily life

Tea remains the most consumed drink in the world after water, well ahead of coffee, beer, wine, and carbonated soft drinks An accumulated number of population studies suggests that consumption of green and black tea beverages may bring positive health effects High levels of flavonoids in tea can protect cells and tissues from oxidative damage by scavenging oxygen-free radicals Chemically, the flavonoids found in green and black tea are very effective radical scavengers The tea flavonoids may therefore be active as antioxidants in the digestive tract or in other tissues after uptake A substantial number of human intervention studies with green and black tea demonstrates a significant increase in plasma antioxidant capacity in humans approximately 1h after consumption of moderate amounts of tea (1-6 cups/d) There are initial indications that the enhanced blood antioxidant potential leads to reduced oxidative damage to macromolecules such as DNA and lipids Tea flavonoids are potent antioxidants that are absorbed from the gut after consumption Tea consumption consistently leads to a significant increase in the antioxidant capacity of the blood Beneficial effects of increased antioxidant capacity in the body may be the reduction of oxidative damage to important biomolecules

The seeds of the tropical tree Theobroma cacao L are used to make cocoa beans Because of the high concentration of bioactive chemicals, such as catechins, epicatechins, and procyanidins, which are antioxidants Not only in the food industry, but also in the pharmaceutical and cosmetic industries, they are in high demand Cocoa beans have a substantially higher antioxidant content per serving than black tea, green tea, or red wine, according to Lee et al (2003) Interest in these cocoa components has risen in recent years as a result of their potential health benefits To prevent or delay cellular damage, cocoa antioxidants can either quench free radicals or chelate transition metal ions, limiting their ability to form reactive oxygen species They also have a number of physiological characteristics that help them avoid diseases Catechins (flavan-3-ols) (37 percent), anthocyanins (4 percent), and proanthocyanidins (58 percent) are the three primary categories of antioxidants (polyphenols) found in cocoa (Theobroma cacao L.) and cocoa products (Wollgast & Anklam, 2000)

Coffee is very rich in antioxidants — including the hidroxycinnamic acid family (caffeic, chlorogenic, coumaric, ferulic, and sinapic acids) as well as other biologically active chemicals having antioxidant potential, such as caffeine, nicotinic acid, trigonelline, cafestol, and kahweol During processing, the antioxidant profile of coffee changes due to the degradation of native antioxidants and the formation of new ones Thus, the antioxidant capacity of coffee is related to the presence of both natural constituents and compounds formed during processing (roasting) (Vignoli et al., 2011) Low water activity and high temperatures favor the development of Maillard reactions (MR), and the formation of MR products between proteins and carbohydrates (Borrelli

et al., 2004)

Cocoa nibs contain about 55% butter, which accounts for about 30% of the finished chocolate Saturated fatty acids are found at the 1,3-position and oleic acid is found at the 2-position in cocoa butter triglycerides Talbot (1999) found that oleic (34%), stearic (36%), and palmitic acid (27%) fatty acids are present, along with polar lipids, sterols, and tocopherols, depending on growing conditions and provenance Chocolate melts at temperatures ranging from 23 to 37oC due to its basic glyceride makeup Form V (β2) of the lipid crystal is the most desirable in chocolate manufacture and dominates in well-tempered chocolate Whole cocoa beans are used to make cocoa butter The beans are fermented before being dried for use in chocolate production To make cocoa nibs, the beans are roasted and separated from their hulls The cocoa nibs are ground to make cocoa mass, which becomes liquid at temperatures above the melting point of cocoa butter and is referred to as cocoa liquor or chocolate liquor To separate the cocoa butter from the non-fat cocoa solids, the chocolate liquor is squeezed Deodorization of cocoa butter is occasionally done to remove strong or unpleasant flavors

Cocoa butter is used in chocolate to keep sugar particles suspended and lubricated Although cocoa butter reduces the viscosity of melted chocolate, it has little flavor of its own and hence does not contribute significantly to the flavor of chocolate Cocoa butter has a variety of distinct qualities that make it a highly sought-after fat For technological and economic reasons, cocoa butter alternatives such as cocoa butter equivalents (CBEs), cocoa butter substitutes (CBSs), and cocoa butter replacers (CBRs) can partially replace cocoa butter in chocolate manufacture

PART 1: ANTIOXIDANTS IN TEA, COFFEE AND COCOA AND THEIR CHANGES DURING PROCESSING

I Antioxidants in tea, coffee, and cocoa

1 Tea

Tea, made from the leaves of the Camellia sinensis plant, is one of the world's most popular beverages It has been consumed on a daily basis Nonfermented green tea, semifermented oolong tea, and fully fermented black tea are the three varieties Fresh tea leaves are steamed or pan-fried to prepare green tea, which inactivates enzymes and inhibits the oxidation of tea polyphenols

These chemical compounds act as antioxidants, which control the damaging effects of free radicals in the body By stealing electrons from DNA, free radicals can cause mutations that raise LDL cholesterol or change cell membrane traffic, both of which are damaging to human health Though green tea is thought to be higher in polyphenols than black or oolong (red) teas, studies demonstrate that, with the exception

of decaffeinated tea, all plain teas have similar amounts of these compounds, but in varying quantities Green tea has the most epigallocatechin-3 gallate, while black tea contains the most theaflavins; studies have shown that both have health benefits Herbal teas contain polyphenols as well, however the amount varies greatly depending on the plant

Tea consumption has been linked to a lower risk of chronic illnesses including cardiovascular disease and cancer in epidemiological studies There are also laboratory research that show tea intake has health benefits The polyphenol chemicals in tea are thought to be responsible for these benefits The most abundant polyphenols in green tea are catechins Theaflavins and thearubigins, which are generated by the oxidation and polymerization of catechins during fermentation, are the major colours in black tea Despite accounting for up to 60% of the dry weight of black tea extract, the chemistry

of thearubigins remains unknown

• Flavonoids

Polyphenols, also known as flavonoids, are most likely one of the factors that contribute to tea's health benefits Flavonoids are plant secondary metabolites that may be separated into six groups depending on the structure and conformation of the heterocyclic oxygen ring (C ring) of the basic molecule: flavones, flavanones, isoflavones, flavanols, flavanols, and anthocyanins (Fig 1) fAvanols and favonols are the two primary types of favonoids found in tea Different quantities of tea samples were extracted with varying solvents for varied durations of time at different temperatures, resulting in different extraction efficiencies After acid hydrolysis, the content of flavonols in green tea leaves ranged from 0.83 to 1.59, 1.79 to 4.05, and 1.56 to 3.31 g kg-1, while the content of flavonols in black tea leaves ranged from 0.24 to 0.52, 1.04 to 3.03, and 1.72 to 2.31 g kg-1 for myricetin, quercetin, and kaempferol, respectively

Figure 1 Basic structure of flavonoids

• Catechins

Many different types of polyphenols and catechins may be found in tea Catechins are the most abundant Catechins are molecules with a C6-C3-C6 carbon structure and two aromatic rings, A and B, that belong to the flavonoids group

Figure 2 The basic structural formulas of tea catechins

Seven different types of catechins are contained in the tea plant, as well as traces

of additional catechin derivatives There are two types of catechins: free catechins and esterified or galloyl catechins Catechins may be found in all areas of the tea plant; about 15–30 percent can be detected in the tea shoots, and the second and third leaves have high catechin contents Catechin content is highest in August when the light of the sun is the strongest

The synthesis of free catechins declines over time, whereas galloyl catechins rise Catechins are abundant in the bud and higher leaves Details that, Zaprometov investigated the synthesis of tea catechins C was found in the four primary catechins when CO2 was absorbed with the tea leaves for two hours

Figure 3 The structural formulas of catechins

• Polyphenolic catechins in green tea

The polyphenolic catechins which is an antioxidant in green tea (Camellia sinensis) They are quite abundant Green tea consumption may reduce the risk of cardiovascular disease (CVD) and nonalcoholic fatty liver disease (NAFLD) (NAFLD) In green tea, catechins contain antioxidant and anti-inflammatory properties, which help to reduce oxidative stress reactions linked to CVD Considering the low bioavailability of dietary catechins, the antioxidant effects of green tea catechins are expected to be mediated by indirect pathways Green tea is good anti-inflammatory properties, which are mediated in part by its antioxidant properties, inhibit nuclear factor kappa B (NFB) activation, and NFB-dependent pro-inflammatory responses

Figure 4 Chemical structures of the predominant catechins found in green tea Green

tea catechins include both catechin and epicatechin forms Gallated catechins include epigallocatechin gallate (EGCG), gallocatechin gallate (GCG), epicatechin gallate (ECG), and catechin gallate (CG) The major non-gallated catechins are epicatechin (EC), catechin (C), epigallocatechin (EGC), and gallocatechin (GC)

• Theaflavins

Theaflavins, which give black tea its vivid red color, have a benzotropolone skeleton that is generated by the co-oxidation of two catechins, one with a victrihydroxyphenyl moiety and the other with an orthodihydroxyphenyl structure The qualities of black tea, including as color, 'mouthfeel,' and the degree of tea cream development, are all influenced by theaflavins Their structures have been thoroughly investigated Theaflavin, theaflavin 3-gallate, theaflavin 30 -gallate, and theaflavin 3,30-digallate (Figure 5) are four primary theaflavins in black tea that are formed by oxidative coupling between EC and EGC, EC and EGCG, ECG and EGC, ECG, and EGCG, respectively

Figure 5 Structures of major theaflavins in tea

2 Coffee

Coffee is a popular beverage that has long been used as a meal complement as well as a hedonistic and psychostimulant It is believed that 80 percent of the adult population in the world consumes coffee beverages (Sridevi et al., 2011) Although coffee has been widely used for centuries due to its pleasant aroma, modern epidemiological research has found that regular coffee consumption provides a number

of health benefits due to its biochemical composition Coffee contains vitamins such as B3 and B12 Coffee also contains additional beneficial chemical elements such as antioxidants, fiber, and melanoidins, among others Coffee is high in antioxidants from the hidroxycinnamic acid family (caffeic, chlorogenic, coumaric, ferulic, and sinapic acids) as well as other biologically active chemicals having antioxidant potential, such

as caffeine, nicotinic acid, trigonelline, cafestol, and kahweol as presented in table 1 (Sridevi et al., 2011)

Antioxidant activity of coffee is related to chlorogenic, ferulic, caffeic, and

n-coumaric acids contained in it

Table 1 The main antioxidants in Arabica coffee and Coffea canephora (Robusta coffee)

• Chlorogenic acids (CGAs)

Chlorogenic acids (CGAs) are a family of esters that are structural analogs of quinic acid (QA) carrying one or more cinnamate derivatives such as caffeic, ferulic, and p-coumaric acids (Narita & Inouye, 2015)

CGA's biological qualities have recently been described, in addition to its antioxidant and anti-inflammatory activities CGA is thought to have a key role in glucose and lipid metabolism, as well as related illnesses such as diabetes, cardiovascular disease (CVD), obesity, cancer, and hepatic steatosis CGA's anti-diabetic, anti-carcinogenic, anti-inflammatory, and anti-obesity properties may give

a non-pharmacological and non-invasive strategy to treating or preventing several chronic conditions Certain plant species generate chlorogenic acid (CGA), a physiologically active dietary polyphenol that is a primary component of coffee CGA consumption has been linked to a reduction in the risk of a variety of diseases

in current fundamental and clinical research investigations

Figure 6 Chemical structures of CGAs from green coffee beans (A) Structures of key

groups of and quinic acid found in CGAs from green coffee beans

The content of CGAs in green coffee beans for human consumption (C arabica and C canephora) is in the range of 3.40–14.4% w/w dry matter, though that in some Coffea species is <1% w/w dry matter Eighty-two CGAs were detected in green coffee beans The contents of total CGAs, caffeoylquinic acids, feruloylquinic acids, and diferuloylquinic acids in commercial roasted coffee beans are 2.66%, 2.26%, 0.21%, and 0.19% w/w dry matter as showed in table 3, respectively The content of CGAs in commercial instant coffee is CGA in the range of 3.61–10.73% w/w dry matter (instant coffee powder)

Table 2 Contents of Chlorogenic Acids (CGAs) of Green Coffee Beans (Coffea arabica

and Coffea canephora)

Table 3 Contents of Chlorogenic Acids (CGAs) of Roasted Coffee Beans (Coffea

arabica and Coffea canephora)

• Caffeine

Caffeine is an alkaloid found in different levels in brewed coffees and is well recognized for its effects on mental alertness, information processing speed, wakefulness, restlessness, fatigue decrease, and sleep deferral It's also accessible

as a tablet and is widely utilized in pharmaceuticals and beverages Caffeine level

in coffee brews varies depending on bean variety, brewing strength, and roasting procedure In general, the caffeine concentration of the same variety of coffee bean brewed in the same way can range from 130 to 282 mg/240 mL, with Arabica brewed coffee containing between 36 and 112 mg caffeine/100 mL and Robusta brewed coffee containing between 56 and 203 mg/100 mL(Komes & Bušić, 2014)

Figure 7 Chemical structure of caffeine (1, 3, 7-trimethylxanthine)

Caffeine and its catabolic products theobromine and xanthine exhibit both antioxidant and pro-oxidant properties Therefore, caffeine and its metabolites may also contribute to the overall antioxidant and chemopreventive properties of caffeine-bearing beverages (Azam et al., 2003) There is conflicting evidence regarding the contribution of caffeine to the antioxidant capacity of coffee brews While Brezová et al (2009) found a high antioxidant capacity of caffeic acid but not

of caffeine, Vignoli et al (2011) reported high correlations between antioxidant capacity of coffee brews and caffeine Similarly, López-Galilea et al (2007) reported a significant correlation between caffeine content and antioxidant capacity obtained by DPPH (r=0.83) and redox potential (r=0.84), depending on the brewing technique In addition, Santini et al (2011) also observed a direct relation between caffeine content of Arabica coffee brews and corresponding antioxidant capacity

• Trigonelline

Trigonelline is a bitter alkaloid in coffee which serves to produce important aroma compounds In terms of concentration trigonelline is higher for arabica than robusta and ranges from about 0.6-1.3% and 0.3-0.9%, respectively Trigonelline (1-methylpyridinium-3-carboxylate) is one of the major components of coffee beans, representing ∼2% of the dry weight (Mazzafera, 1991) It is also one of the candidate compounds responsible for the bitter taste of the coffee brew Trigonelline

is thermally unstable and during roasting it is converted to nicotinic acid and other nitrogenous compounds that contribute to flavor (Mazzafera, 1991) During germination of coffee seeds, limited content of trigonelline is catabolized and used

as a substrate for the synthesis of nitrogen containing compounds (Shimizu and Mazzafera, 2000) Trigonelline, demethylated to nicotinic acid, supplies 1–3mg of nicotinic acid/240ml of brewed coffee (Higdon and Frei, 2006; Stadler et al., 2002)

Figure 8 Chemical structure of trigonelline.

• Tocopherols

Tocopherols are a group of four lipid-soluble amphipathic molecules (α-, β-, γ-, δ-) that are exclusively synthesized by photosynthetic organisms Collectively, they are an essential component of vitamin E (Gilliland et al., 2006), which is known to be the most effective natural lipid-soluble antioxidant, protecting cell membranes from peroxyl radicals and mutagenic nitrogen oxide species (Gliszczyńka-Świgło and Sikorska, 2004) The presence of tocopherols

in coffee oil was reported for the first time by Folstar et al (1977)

Among tocopherols, two main tocopherols (α- and β-) were identified in Arabica and Robusta coffee beans, both green and roasted (Alves et al., 2010) Ogawa et al (1989) reported vitamin E mean content in coffee brew of 7±3μg/100ml The content of α-tocopherol in roasted coffees ranged between 7.55 μg/g and 33.54 μg/g, whereas in green coffees it was between 2.02 μg/g and 16.76 μg/g In the case of β- and γ-tocopherols, remarkable differences between green and roasted samples were observed, with their contents being higher in roasted coffees Thus, the mean values of β-tocopherol were evaluated to be 47.12μg/g and 106.60μg/g for green and roasted coffees, respectively In the case

of γ-tocopherol, its content varied between 2.63μg/g in green samples and 70.99μg/g in roasted coffee beans (Gonzales et al., 2001) The increase in tocopherol content during the roasting process has been already described for some oilseeds (Yen, 1990), and was explained as the result of liberation of the combined tocopherols during the roasting process

Recently, the usefulness of tocopherol content and profile as a marker of coffee adulteration with corn was also described by Jham et al (2007)

3 Cocoa

Cocoa beans are the seeds of the tropical tree Theobroma cacao L Because of the high concentration of bioactive compounds, including antioxidants - catechins, epicatechin, and procyanidins They're in high demand not only in the food sector, but also in the pharmaceutical and cosmetic industries According to Lee et al (2003) cocoa beans contain much higher antioxidant capacity per serving than black tea, green tea and red wine Because of their possible beneficial impacts on human health, interest in these cocoa components has soared in recent years Cocoa antioxidants can either quench free radicals or chelate transition metal ions, reducing their ability to produce reactive oxygen species, to prevent or delay cellular damage They also have a variety

of physiological features that protect them from diseases such as coronary heart disease, cancer, and neurological disorders Antioxidants (polyphenols) in cocoa (Theobroma cacao L.) and cocoa products can be classified into three main groups: catechins (flavan-3-ols) (37%), anthocyanins (4%), and proanthocyanidins (58%) (Wollgast & Anklam, 2000)

Forsyth reported that cocoa bean contains four types of catechins, of which epicatechin constitutes about 92% The primary catechin is (−)-epicatechin, up to 35%

(-)-of total polyphenols and from 34.65 to 43.27 mg/g (-)-of defatted freshly harvested Criollo and Forastero beans Less abundant is (+)-catechin with only traces of (+)-gallocatechin and (−)-epigallocatechin Nazaruddin et al (2001) reported total polyphenols ranged from 45 to 52 mg/g in cocoa liquor, 34 to 60 in beans and 20 to 62 in powder: (−)-epicatechin contents were 2.53, 4.61 and 3.81 mg/g, respectively The contents of (-)-epicatechin was 2.23 ± 0.6 mg/g These data are just used for references and cannot be directly compared with the data found in other publications, due to differences in methods of phenolic extraction, data from our study fall within the range found in the literature

The anthocyanin fraction is dominated by cyanidin-3-α-l-arabinoside and cyanidin-3- β-d-galactoside Total procyanidins accounted for a mean percentage of 63.71% of the total phenolics Procyanidins are mostly flavan-3,4-diols and are four to eight or four to six bound to form dimers, trimers, or oligomers with epicatechin as the main extension subunit The contents of dimers epicatechin-(4β→8)-catechin (procyanidin B1) and (epicatechin-(4β→8)-epicatechin) procyanidin B2 were 0.28 ± 0.03 mg/g and 0.63 ± 0.03 mg/g, respectively Procyanidins are converted to largely insoluble red-brown material resulting in the characteristic color of chocolate during fermentation and roasting

Figure 10 Structures the catechin and epicatechin enantiomers

Figure 11 Structures of procyanidin dimer and trimer in cocoa

Polyphenol oxidase promotes oxidative browning to give the characteristic chocolate brown color of well-fermented Forastero beans

II Changes of antioxidants in tea, coffee and cocoa during

processing

1 Tea

Identification of catechins, theaflavins, and flavonols in green and black tea samples

Rolling and Drying

Catechins, theaflavins, and flavonols demonstrated different changes in composition and content in each processing step of green and black teas (Table 4)

Table 4 Mass spectrometric data and contents (mg/100 g dry weight) of individual

flavonoids in each processing step of green and black tea (Camellia sinensis) leaves

The total flavonoid content of green tea was significantly increased after the roasting step Specifically, major catechins, EGCG and ECG, reached the highest level

on the final product, and their contents (mg/100 g DW) increased approximately twofold over fresh leaves Theaflavins were present in the fresh leaves but vanished after roasting Heating processing (250–300 °C) was considered to cause the increase

or decrease of certain components through drying or hydrolysis under water-free

it was difficult to conclude that the significant increase in catechin was entirely due to water evaporation of the fresh leaf Based on these findings, the roasting step is also expected to reduce catechin content loss by inactivating the polyphenol oxidase (PPO) enzyme, which leads to catechin degradation in fresh leaf

The contents of catechins and flavonols, on the other hand, were significantly reduced by the rolling step and then increased again after drying steps in green tea The loss of ECG and EGCG contents during leaf processing was reduced as the rolling time was reduced The flavonols tended to reach their maximum level over the three drying steps, but there were no significant differences in mono- and tri-glycosides, as well as total content, until the final product was completed over the second and third drying steps (Fig 12b) In particular, as a major class, kaempferol mono- and tri-glycosides (peak 12, 15, 16, and 18) had the highest contents, while quercetin mono- and tri-glycosides (peak 8, 9, 13, and 14) had slightly lower contents than the previous step on the final product (Table 4) Roasting and drying were found to be the most important factors in changing individual catechin and flavonol contents in green tea processing

Figure 12 Distribution of flavonoids by tea leaf processing a Variation of theaflavin

contents (mg/100 g dry weight, DW) by acylated forms (aglycone, mono- and

di); b variation of flavonol contents (mg/100 g DW) by glycosidic forms (aglycone,

mono-, di-, and tri-)

Fermentation

Fermentation is the critical step in the production of black tea leaf that results in the greatest change in flavonoid composition and content The majority of studies have looked at flavonoid changes in simple fermented teas such as black, oolong, and Pu'er teas The chromatogram in Figure 13a showed that catechins were almost certainly converted to theaflavins during the fermentation step of black tea Fermentation, in general, is one of the most affected methods of changing the ingredients in agro-food processing Catechins, on the other hand, induce a condensation reaction after oxidation

by PPO enzyme to form theaflavins, thearubigins, and proanthocyanidins with high molecular weight during black tea processing, and the higher concentration of theaflavins could be due to this chemical phenomenon (Fig 13c) The catechin content (mg/100 g DW) increased slightly during withering and then decreased significantly during the rolling and fermentation steps When it became the final product after drying, the reduced content of individual catechins was roughly doubled again (Table 4) The total theaflavin content (mg/100 g DW) increased significantly throughout the entire black tea processing sequence: withering → rolling → fermentation → first drying → second drying → final product In Figs 13c and 1a, theaflavin 3,3′-di-O-gallate (305.6) and theaflavin 3-O-gallate (168.4), which were advanced with gallic acid in the biosynthetic pathway, showed the greatest increases of 4.5- and sixfold as predominant compounds, respectively, when compared to fresh leaf