topic discuss the processing techniques or methods on the quality of specific food products

In the process of introducing the culture of making soy sauce, other countries have adjusted the proportions and ingredients to suit their taste, making soy sauce more flavorful and colo

NONG LAM UNIVERSITY, HO CHI MINH CITY FACULTY OF CHEMICAL ENGINEERING & FOOD TECHNOLOGY

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TOPIC:

Discuss the processing technique(s) or method(s) on the quality gi

specific food products

Full Name: Le Hoang Kim Khanh Class: DH21TP

Student’s ID: 21125150 Instructor: Assoc Prof., Dr Kha Chan Tuyen

Ho Chi Minh City, 13" April 2023

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Tables of Contents

| INTRODUCTION

Il MAIN CONTENTS

1 The soy Sauce’s processing

1.1 Traditional brew method

1.1.2 Moromi fermentation (anaerobic process) 1.2 Modern brew method

2 Factors affecting soy sauce quality

2.1 Raw materials

2.2 Fermentation conditions

2.3 Microbial community in soy sauce fermentation

2.4 Process engineering

2.5 Salt reduction in soy sauce production and its effect on moromi

fermentation

Ill CONCLUSION

IV REFERENCES

| INTRODUCTION

Soy sauce is a liquid condiment originating from China, which has light brown to black color with a salty and intense umami flavor During the making of soy sauce, wheat, soybeans, water, and salt is the main ingredient fermented A complex procedure is used to combine these ingredients with mold spores, yeast, and lactic acid bacteria to create a mash The final product is created by pressing, maturing, and filtering the mash The origins this versatile sauce was originally used to preserve food and improve its flavor in ancient China Due to its distinct flavor and aroma, soy sauce is widely used as a seasoning in Japan, China, Korea, and other Asian countries, and it has since gained popularity in Western countries In the process of introducing the culture of making soy sauce, other countries have adjusted the proportions and ingredients to suit their taste, making soy sauce more flavorful and colorful but they all go through the same koji and moromi two-step fermentation process Koji is a solid-state fermentation process that uses mold spores to ferment soybeans and wheat The processing of moromi is take place by submerging the resulting koji in a brine solution and allowing it to ferment for several months - up to 4 years During the process of making soy sauce, many factors can affect to change the quality of products such as raw materials, fermentation conditions, microbial community, etc Due to the non-sterile environment and lengthy fermentation process, the interdependence of various microbial species, such as bacteria, yeast, and fungi, is complicated when making soy sauce Microbial activity significantly contributes to the stability and consistency of the final soy sauce ingredients Traditional soy sauce

is made through a two-stage primary fermentation process that starts with a brief solid-state fermentation (koji) and ends with a lengthy liquid-state fermentation (moromi) During the moromi stage, which has a salt content of 18-20%, the Aspergillus genus (primarily A oryzae or A sojae) dominated microorganisms in the koji fermentation step produce enzymes that break down soybean and wheat into simple molecules These molecules are then used for the development of halophilic bacteria, such as lactic acid bacteria (LAB), Bacillus species, and yeasts Despite the positive perception of soy sauce in terms of its nutritional value and health benefits,

as well as recent advancements in its production, a number of issues still need to be fixed For instance, numerous attempts have been made to use genetic engineering techniques, cell and enzyme immobilization, and other techniques to shorten the lengthy fermentation time during the moromi stage without compromising the final product's quality Furthermore, soy sauce’s high salt content raises concerns due to its negative effects on health, including hypertension and renal dysfunction Thus, soy sauce has been reduced to between 8% and 11% due to industry pressure to lower dietary sodium salt intake However, because it controls microbial and organoleptic properties, salt is a crucial component in the fermentation of soy sauce As a result, its reduction could compromise the quality of the finished product in addition to raising questions about microbiological safety

Il MAIN CONTENTS

1 The soy sauce’s processing

1.1 Traditional brew method

The four basic components that make up soy sauce are soybeans, wheat, salt, and water Soy sauce is always fermented in two steps, namely koji (solid-state fermentation) and moromi (brine fermentation) Koji contains a wide range of proteolytic enzymes that digest soybean proteins into peptides and amino acids, as well as amylase for hydrolyzing starch into simple sugars The converted substances are ultimately used by yeasts and lactic bacteria in brine fermentation

1.1.1 Koji fermentation (aerobic process)

The first step in the Koji fermentation process by soaking soybeans in water to facilitate the removal of their hulls, increase their moisture content, and flush out fungi inhibitors, which is the step that is necessary for the fungi to grow Additionally, during the soaking process, spontaneous fermentation takes place, lowering the pH

of the soybeans to 4.5-5.0 When koji fermentation, the low pH help supports the growth of fungi while restricting the development of spoilage microorganisms After soaking time, soybeans are cooked in batches using a pressure cooker with saturated steam at 0.8—-1.0 kg/cm * gauge pressure for 40-45 min, or using a continuous cooker

at 6-7 kg/cm? gauge pressure (about 170 °C) for 20-30s The quantity of bacteria,

yeasts, and molds in soybeans decreases at this point due to the high temperature and pressure used during cooking During this time, wheat is roasted in a hot air continuous cooker at 150 °C for 30-45 seconds at atmospheric pressure After it has been roasted, the wheat is ground into flour with smaller grains The soybeans and wheat flour are combined with a small amount of fungal spores, most commonly A oryzae orA sojae The mixture is loaded into trays in layers thick about 3-5 cm and incubated at 25 degrees Celsius During this phase, koji mold produces amylase, which breaks down starch into simple sugars and proteolytic enzymes that hydrolyze proteins into peptides and amino acids The enzymatic activity of fungi causes heat production and an increase in the pH of koji from 6.5 to 7.3 The temperature is kept between 25 and 28 °C by routine stirring, which lowers the heat produced by the

fungal metabolic activity After three days of incubation, sporulating fungal mycelia grow on the surface of soybeans, resulting in a compact mass of greenish soybeans 1.1.2 Moromi fermentation (anaerobic process)

The second stage of making soy sauce is moromi fermentation Moromi mash is created by immersing koji in a brine solution containing 18-22% NaCl The high salt concentration in brine inhibits the growth of spoilage microorganisms and pathogens while promoting the development of halotolerant species that play an essential role

in flavor formation Mold growth and enzymatic activity in koji are halted due to high salt concentration Thus, moromi fermentation is primarily driven by indigenous halotolerant lactic acid bacteria (LAB) and yeast LAB multiplies rapidly at the start

of the moromi fermentation, and the pH gradually decreases due to lactic acid fermentation and other metabolic products When the pH of moromi mash reaches 4.0-5.0, the bacterial population begins to decline while the yeast population begins

2

to increase After fermenting for 3 to 6 months, moromi is refined by carrying out pressing, filtration, pasteurization, and packaging The matured moromi is pressed through layer filters to separate solids from liquid raw soy sauce The raw soy sauce

is then pasteurized at 70-80 °C for 30 min to destroy any remaining microorganisms and enzymes and extend the product's shelf life Additionally, the heating process results in the production of several aroma compounds Some manufacturers can be added ingredients such as caramel to the soy sauce to adjust the color Before being delivered to the market for consumer consumption, soy sauce is packaged in plastic

or glass containers The average soy sauce shelf life in plastic and glass containers is 1.5 and 3 years, respectively

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Soybean

©- Wheat Roasting vu

Ley Koji fermentation

Inoculation of Aspergillus oryzae

or Aspergillus sojae

Koji making

Moromi

‘Salt Brine solution 8 a fermentation

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Inspectionand pasteurization of raw Pressing and filtration — Soy sauce residue

Feed Waste taming

Figure 1 Flow chart of typical fermented soy sauce production process

1.2 Modern brew method

This method also has four basic components that produce soy sauce soybeans, wheat, salt, and water The process of making koji is now fully automated in modern production, applying equipment like a continuous soybean cooker, a wheat roaster, a mixer, a cooler, an automatic inoculator, a mechanical mixer, temperature controllers, conveyors, and mechanical mixers to stir the mixture during incubation Modern production combines cultures of LAB T halophilus and yeast Z rouxii and Candida species to achieve consistent product quality The modern method of making soy sauce involves a careful balance of science and tradition to produce a high-quality product that people worldwide enjoy and that is good for their health

2 Factors affecting soy sauce quality

2.1 Raw materials

Soy sauce products share a similar production process, but their taste and composition are different because of the different ratios of raw materials used, the duration of the fermentation, the temperature, or the addition of additives, flavorings, taste developers, and preservatives Soy sauce separates into two varieties based on the amount of wheat it contains: The Japanese type uses an equal number of soybeans and wheat, while the Chinese type uses a greater proportion of soybeans and less wheat Each type of soy sauce has a different microbial composition because different amounts of wheat are used, which alters the amount of sugar available during fermentation Chinese soy sauce uses less wheat than Japanese soy sauce, so yeast fermentation is not as significant Japanese soy sauce is divided into five classes based

on the soybean and wheat content used: koikuchi, which accounts for 80% of the Japanese soy sauce production, usukuchi, tamari, saishikomi, and shiro The ratio of each material in the components is slightly different, which also affects the quality of the products

2.2 Fermentation conditions

Fermentation conditions also make significant changes in soy sauce quality, such as incubation period, temperature, pH, and salinity Chinese soy sauce is also categorized as high salt liquid-state fermentation soy sauce (HLFSS) and low salt solid-state fermentation soy sauce (LSFSS) The two differ depending on the fermentation process, salinity, aging period, and production temperature HLFSS is carried out at ambient temperatures (15-30 °C) over a long aging period of 90-180 days with a brine concentration of 17%-20% In contrast, LSFSS is made at higher temperatures (40-55 °C), which shortens the fermentation period to 15-30 days while using a brine solution with a lower concentration (13%-15%)

2.3 Microbial community in soy sauce fermentation

In traditional production, the koji and moromi stages are performed in a non-sterile environment, leading to spontaneous fermentation by indigenous microbes A wide range of species have been isolated and identified during the soy sauce fermentation process, and their activity strongly influences flavor and aroma formation in the final product However, since the microbial community involved in soy sauce fermentation

is very complex, controlling the process is difficult, resulting in inconsistency in the quality of the final product Every step of the production process causes changes to the soy sauce's microbiome Due to the high salt content in moromi, it was discovered that koji had a higher microbial diversity than moromi Bacteria, particularly LAB, were the dominant organisms in Koji, followed by yeasts and molds While Klebsiella, Paenibacillus, and Corynebacterium were only found in the koji stage, other bacterial groups (Staphylococcus, Bacillus, and Enterobacter) persisted throughout the moromi stage During the fermentation of moromi, the microbial diversity evolves over time The microbial diversity decreased as the fermentation progressed, especially in the middle to late stages of moromi fermentation The main cause of this decline is the moromi's high salinity, which makes it difficult for non- halotolerant microbes to grow Nevertheless, a few bacteria species had the ability to

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survive in high salt concentrations Increased acidity caused by bacterial organic acid production allows acid-tolerant yeasts to dominate fermentation During the moromi stage, the proportion of yeasts in the microbial population also changes Z rouxii was only found in the mid to late stages of moromi fermentation and was thought to be the most dominant fungus in this stage The fermentation process for soy sauce is carried out more precisely and sterilely in modern production Modern soy sauce production uses a defined mixed starter culture instead of traditional production, which depends on the spontaneous growth of local microorganisms Thus, the complexity of the microbial diversity is lower

2.4 Process engineering

Regardless of the soy sauce origin and production method can be slightly changed, but T halophilus and Z rouxii have been considered the most predominant microbes

in the moromi stage The pH of moromi has been predicted to be the main factor affecting the antagonistic interaction between T halophilus and Z rouxii during fermentation since these species require different acidity for optimum growth T halophilus grows at slightly higher pH levels (5.5-9.0), whereas Z rouxii requires slightly acidic pH levels (4.0-5.0) in a substrate that contains 18% salt Z rouxii and

T halophilus grow in parallel during spontaneous fermentation When the fermentation of moromi first begins, the pH is between 6.0 and 7.0, which is beneficial for T halophilus growth Moromi becomes more acidic as a result of T halophilus growth and the resulting production of organic acids Once the pH drops below 5.0, T halophilus can no longer grow Z rouxii can begin to grow and produce alcohol at this pH by making use of the glucose found in the morori It is challenging

to maintain the consistency of the flavor quality of the final product in the traditional process because the fermentation conditions are not well controlled A variety of microbial species make up the mixed starter culture, which is necessary for flavor enhancement To produce and add to the flavor of soy sauce, T halophilus and Z rouxii mixed cultures have been used Compared to the pure culture of Z rouxii, the co-culture of these two species produced more alcohols, furanone, esters, maltol, and benzoic acid The aroma that develops during the moromi stage is also influenced by the microbes used in koji fermentation When using mixed starter cultures, flavor enhancement is greatly influenced by the inoculation time The precursors of the aroma compounds may have accumulated if Z rouxii inoculation was postponed When Z rouxii is added to moromi after T halophilus, the pH is reduced to 5.0, which can produce aroma profiles with more nuance

2.5 Salt reduction in soy sauce production and its effect on moromi

fermentation

There has been an increase in demand for low-salt soy sauce because of health concerns associated with high sodium intakes, such as hypertension and renal dysfunction As a result, producing soy sauce with a low salt content but maintaining quality has become a challenge for the industry The high salt concentration is used

in soy sauce production to create anaerobic conditions in moromi, prevent autolysate putrefaction, and inhibit spoilage microorganisms’ growth It is also important for the organoleptic properties of soy sauce, such as texture and aroma Physical removal

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methods such as nanofiltration, ion exchange, reverse osmosis, freezing, and extraction have been used to reduce salt in downstream processing Although some

of them are claimed to have no negative effect on soy sauce flavor, they appear to be unviable for commercial use due to high operating costs Other studies focused on reducing the amount of salt used during moromi fermentation Because the high salt content of moromi can slow microbial metabolic activity, fermentation must be completed within 6 months Low NaCl concentrations can be co mbined with physical treatments to accelerate fermentation while maintaining quality This treatment was carried out in order to obtain soy sauce with the same chemical composition and flavor as traditional soy sauce The application of 10-minute ultrasonication at daily intervals during moromi fermentation has also been shown to speed up the process in the presence of 5% NaCl Many conditions allowed for higher production of glutamic acid and MSG-like amino acid, total and essential free amino acid contents within 4 days of fermentation, whereas untreated moromi reached the same levels on day 7 The researchers proposed that ultrasonication could bring the peptide and proteolytic enzymes closer together, accelerating the peptide cleavage rate and efficiently extracting free amino acids (FAAs) in moromi A high FAA content is desirable for obtaining a final product with high sensory qualities Way to enhance the perception

of saltiness in low-salt soy sauce, several chloride salts, such as KCI, MgCl, and MnClz, and amino acid-based saltiness enhancers could replace NaCl However, it

suggested that MgClz and MnClez added no saltiness in soy sauce, while KCI caused

bitterness, which became apparent when added at a concentration above 10% The effect of partial substitution of NaCl with KCI on moromi fermentation pattern and aroma formation The substitution with KCI was shown to improve the growth of T halophilus while having no effect on Z rouxii This resulted in faster sugar consumption and increased lactic acid production by T halophilus, altering the final aroma profile of moromi NaCl reduction raises a microbiological safety concern in addition to fermentation patterns and organoleptic quality Some believe partial replacement of NaCl with ethanol could prevent the growth of pathogenic and spoilage microorganisms The use of ethanol, on the other hand, may limit the growth

of desirable microorganisms Amino acid-based saltiness enhancers have demonstrated the capacity to produce low-salt soy sauce with better taste quality compared to chloride salts However, the umami and saltiness flavors produced are poorly balanced

Ill CONCLUSION

With the recent emergence of the nutritious food movement, consumers are paying close attention to the relationship between food and health As a result, there has been

a significant increase in demand for health-promoting and functional fermented foods, such as soy sauce The use of well-established starter cultures appears to be the key to improving soy sauce flavor while lowering salt content without compromising final product consistency As a result of the rapid advancements in modern biotechnology and genetic engineering, it is now possible to screen and isolate novel starter cultures and investigate their effects on potential commercial applications without compromising food safety In order to better control the production process and maintain a consistent level of product quality, a well-defined mixed starter culture is crucial When creating starter cultures, it is important to consider the characteristics of different species and the interactions that are seen during soy sauce fermentation As a result, changes to the soy sauce production process can be made without affecting the flavor, such as reducing the salt content during the moromi stage However, depending on the region and the method of production, the microbial species involved in the fermentation process vary greatly among different types of soy sauce Therefore, it is unclear to what extent microbial interactions and composition contribute to the soy sauce's aroma profile Future research could concentrate on linking the microbiome for the purpose of improving flavor quality and microbial control