SOY SAUCEMOKSHA CHIB13FET1003

Introduction

Soy sauce is a light brown to black liquid with a meaty-like, salty flavor produced from soybeans with/without wheat by means of fermentation.

It is a condiment made from a fermented paste of boiled soybeans, roasted grain, brine, and Aspergillus oryzae or Aspergillus sojae molds.

It is the chief savory seasoning agent in Oriental cookery, but it is becoming increasingly popular in many other regions of the world.

Chemical reactions between the original components and the fermentation products create the color , consistency and aroma of soy sauce.

Factors Affecting Microbial Growth

The following factors contribute to the growth of microorganisms.

Intrinsic Extrinsic Implicit Processing

pH Storage temperature

Synergism Fermentation

Water activity Relative humidity Antagonism Refining

Redox potential Composition of atmosphere

Commensalism Pressing

Nutrient content Packaging

Antimicrobial constituents

Nutrient Content

Nutrition Value per 100 ml

Calories 60 kcal

Fat 0.1 g

Carbohydrates 5.57 g

Fiber 0.8 g

Protein 10.51 g

Sodium 6 g

Soy sauce contains:

Amino acids 25% (glutamic acid being the predominant.)Carbohydrates 13% (glucose, arabinose, maltose, xylose & galactose.)Polyalcohols 5% (glycerol, mannitol.)Organic acids 3% (lactic, acetic, succinic, citric, formic, pyroglutamic acids.)

Soy sauce contains 1.5-1.65% of Nitrogen.

40-50% of nitrogen is present in amino acids, Balance is contained in peptides & peptones.

Intrinsic Factors

1. WATER ACTIVITY:

The aw of soy sauce is 0.803 at 25⁰C. Even though it contains 65% w/w of

water, the high salt content binds large amount of water in the product

reducing the free moisture content available for the microorganisms to

grow.

This amount of water activity will not suffice the growth of maximum microbes.

Still, many microbes can grow in deficit amount of water.

2. pH:

Generally, the pH ranges from 4.5-5.5 depending on different commercial

brands. Due to its slightly acidic nature, it is commonly used in alkaline

foods for e.g. in Chinese foods.

This slightly acidic pH favours growth of many microorganisms & hence

measures should be taken to arrest it.

…Intrinsic Factors3 . Salt content:

The salt content of soy sauce is 14-18%. The fact that it does not feel as salty

as all that is because constituents such as amino acids and lactic acid

buffer the salty taste.

Salt content also protects the finished sauce from spoilage as it creates

osmotic pressure inside the cell which leaches out water from the cell and

leaves the organism dormant or lifeless, hence unable to reproduce.

4 . Sugar content:

The sugar content is 6% in soy sauce. The sweetness is due to glucose which

is produced by fermentation of starch in wheat.

Salts & sugars act as antimicrobial agents in soy sauce.

5. Ethanol: A little amount of ethanol is contained in soy sauce that reduces

the growth of various microorganisms.

Extrinsic Factors

Storage Conditions:

If soy sauce is stored in warm temperatures, it may lead to growth of

microflora inside it, if the packaging is not efficient & not enough measures are

taken to eliminate the microorganisms from soy sauce. Also, cleanliness of

storage containers will affect the shelf life.

Storage Atmosphere:

A sufficient amount of oxygen will promote the growth of microorganisms

as well as oxidation of components of soy sauce such as lipids or certain sugars.

Also higher relative humidity will increase the heat as well as the number of

organisms around the packaged product.

Implicit Factors

Synergism:

Coagulase negative Staphylococcus spp. is one of major contaminant of

koji produced soy sauce. These microbes grow symbiotically with

the koji molds & their combination makes a problem when fermented

below 25°C.

Antagonism:

B. Subtillis grows in competition with the koji molds at higher temperatures.

This will affect the quality of final soy sauce.

Spoilage during Processing

Most of the microflora in the sauce is eliminated during heat treatments.

Contaminations may persist after processing due to unhygienic use of processing implements.

During fermentation of soybeans, only selected strains of Asp. Oryzae or Asp. Sojae are used as fungal starters. So the risk of other contaminants is greatly reduced.

During processing, brine is used after fermentation which inhibits the growth of most microorganisms excluding the halotolerant lactobacillus & yeasts such as Ped. Halophilus, which can survive high concentrations of salts.

When raw soy sauce is stored after separation by a hydraulic press from the mash, white dry pellicles are formed on the surface which are caused by the growth of film forming yeast such as Zygosaccharide salsus & Zygosaccharide japonicus.

Microbes involved in Spoilage & Principles

The major microorganisms which are responsible for spoilage of soy sauce include:

1. Salt tolerant(halo-tolerant) Lactobacillus grow in soy sauce & will produce biogenic amines such as tyramine & histamine. Some of these bacteria will also produce ornithine by decomposing arginine resulting in accumulation of citrulline as an intermediate. Ethyl carbamate can be produced by reaction between ethanol and citrulline. This all leads to degradation of soy sauce.

2. A salt tolerant yeast Z. rouxii var. Halomembranis can grow in soy sauce, which is harmless to health but forms a membranous film on the surface of soy sauce causing deterioration of the soy sauce aroma & flavour.

Microbes involved in Spoilage & Principles

Fermented shoyu is found to have bactericidal activity for some enteropathogenic bacteria including S.typhi-shikata, Shigella flexnerii & vibrio-cholerae-inaba. But all of these can be eliminated during later stages of processing i.e. Pasteurisation.

The mycotoxins produced during fermentation have no ill-effects on health. Asp.oryzae & Asp.soyae will not produce any aflatoxins.

Mycotoxins such as cyclopiazonic acid, kojic acid, beta nitropropionic acid or aspergillic acid are harmful & may be present in traditionally prepared soy sauces.

Preservation methods.

My preservation method would emphasise on good pasteurization processes.

A well pasteurized soy sauce will contain no effective contaminations, and hence will extend its shelf life.

After fermentation, the raw soy sauce contains the lactobacillus as well as molds which need to be removed from final product. Also, contaminations present in raw materials, or from the processing instruments, or from the strains of the cultures used, have to be necessarily eliminated, otherwise, it will harm human health as well as spoil the sauce too quickly.

After pasteurization, the main microbial control factor is the high salt content.

In addition to these, use of little amounts of preservatives like sodium benzoate(GRAS) can be incorporated at concentration of 0.5%.

Packaging Perspective

A packaging system should be designed to provide optimal efficiency in storage, economy, etc. It should make product more stable & protect it from microbial attack.

Shelf life is shortened when oxygen, carbon dioxide, water vapour, odours and flavours move out of packages or into them due to which quality is lost.

Hence, permeability of the material is a very important factor that should be considered for packaging.

A very advisable system for packing soy sauce is in a good quality food-grade glass or a High Density Polyethylene polymer plastic bottles that are air-tight which will protect from outer atmosphere and also counter the escape of components from inside the bottles.

Packaging

The next step to be considered is the composition of atmosphere inside the bottles.

My packaging system will incorporate a Modified Atmosphere Packaging(MAP), that would be suitable for a long term storage without addition of preservatives.

In some packaging systems, no head space is left during packaging so as to eliminate oxygen from the system to inhibit growth of organisms.

But absence of oxygen will lead to anaerobic microbial growth, which will cause off odours & flavours. This can be pathogenic and even fatal in case of clostridium botulinum which produces botulinum toxin in absence of oxygen.

A modified atmosphere suggesting elevated levels of carbon dioxide and lowered oxygen levels (most commonly both oxygen & carbon dioxide at 5% )

Storage & Transportation

Storage Conditions:

It should be stored in dark and cool place in order to prevent any oxidation

after it is opened. Such storage prevents the growth of yeast. It is advisable

to refrigerate it even though it is stable at room temperatures. Before it is

open, it is not prone to any spoilage. But gradually the color darkens &

flavor fades.

Transportation:

The packaged bottles should be kept in a carton which is cushioned with

material like bubble wrap during transporting.

This would prevent bumping of bottles into each other and hence will

arrest the leakage which would in turn cause microbial growth as well as

harm to other packaged bottles.

This helps in minimising the transportation losses.

THANK YOU !