Preservation with Biotechnology

Biotechnology

Application of science and engineering in direct or indirect use of living organisms or their parts in their natural or modified forms

Food products of biotechnology

1. fermented beverages (wine, beer)

2. fermented dairy products (yogurt, cheddar cheese)

3. fermented meats (salami)

4. traditional fermented foods (sauerkraut, yakult, miso)

Ingredients and Additives of Biotechnology

1. Amino Acids: Methionine, glutamic acid

2. Biopolymers: Xantham gum, alginates

3. Enzymes: Chromosin, rennin

4. Vitamins: B-vitamins

Modern Food Biotechnology

Beyond fermentation and uses probiotics and GMOs

Preservation principle

the microbial antagonism produces metabolites that lower the pH and create an environment that destroys microflora and pathogens

1. Microbial Antagonism

2. Metabolites

3. Scientists wanted to know how microorganisms actually suppress the other ones

Microbial Antagonism

Our starter culture suppresses growth & metabolic activities of spoilage-causing microflora

Metabolites

• End products of fermentation

• antimicrobial compounds (eg. acids, alcohols)

• Acids (formed in situ) can also lower pH of food

Scientists wanted to know how microorganisms actually suppress the other ones

• the "good ones" don't just eat the food faster; they actively change the chemistry of the food.

• Form metabolites to suppress the growth of other microorganisms

Benefits of fermentation

• preservation

• nutritional value

• variety

Nutritional Benefits of Nutrition

• vitamin B

• Cellulose hydrolyzation

• liberating nutrients from the matrix

Lactic acid bacteria

cucumbers, olives, cabbage, coffee cherries, vanilla beans, meat, dairy

yeasts

mait, grapes, wines, rice, bread dough

mould

soybeans

Lactic acid bacteria (Agent)

RM: Lactose, glucose

FP: Lactic acid

Yeasts (Agent)

RM: Glucose, other fermentable carbohydrates

FP: Ethanol

Acetic acid bacteria (Agent)

RM: Ethanol

FP: Acetic acid

Microbial lipases (Agent)

RM: lipids

FP: Free fatty acids, aldehydes, ketones

Microbial proteinases (Agent)

RM: proteins

FP: Polypeptides, peptides, free amino acids, amines (causes textural and flavour changes in food)

Mould celluloses (Agent)

RM: Cellulose

FP: Oligiosaccharides, glucose

factors affecting fermentation

1. starter culture (MO chosen to do the fermentation)

2. formation of metabolites

3. temperature

4. oxygen

5. salt

starter culture

• needs metabolism for desired products and a dominant microorganism to ensure that MOs suppress their growth

1. starts as a “pure” culture (“yeast”)

2. from a previous batch of fermented food

3. part of the normal microflora

temperature

starter culture will only grow at their optimum temp

Microbial-induced changes

Raw material → fermented product

Oxygen

Fermenting MOs have different O₂ requirements:

1. bakers yeast grows better in aerobic conditions

2. yeast ferments sugars quicker under anaerobic conditions

Salt

• favours growth of lactic acid-producing bacteria

• stops growth of spoilage / disease-causing MOs

Cheddaring

1. liquid whey is drained and warm curds fused into blocks

2. cut and stacked on top of each other

3. blocks are flipped every 10-15 mins for 1-2 hours

4. milled to smaller pieces

Preservation in Cheese

• Moisture content and water activity

• Lactic acid bacteria → acidic conditions (metabolites)

• lactic acid bacteria → microbial antagonism

• salt lowers water activity and inhibits growth of preolytic microorganisms

What aspects of cheese making result in different varieties of cheese?

• Milk (pasteurized? animal"?)

• Curd formation (acid, enzyme, or acid-heat coagulation)

• Starter culture type, time, temp of cooking, washing, pressure

• Ripened (starter cultures, enzymes) or not

• acidity

Swiss Cheese (Hard Cheese)

• lactic and propionic acid bacteria

• secondary starter: propionibacterium freudenreichii

• metabolites:

  • carbon dioxide → eyes

  • proline → sweet

  • propionic acid → nutty flavour

Blue Cheese, Stilton, Gorgonzola and Roquefort (Semi-Soft)

• Blue veined cheese

• Secondary Starter: Penicillium roqueforti

• Curd is needle-inoculated with the mould

• lipase enzymes break down fat, making:

  • Free fatty acids, aldehydes & ketones

  • Sharp, peppery odour and flavour

Mould

• curd is needle-inoculated with the mould

• sharp, peppery odour and flavour

Camembert and Brie (Soft)

• Secondary Starter: Penicillium camemberti

• proteolytic enzymes break down casein from outside in to create the velvety appearance and soft, creamy texture

GMOS

intentional manipulation to MOs, where foreing piece of DNA is inserted into the genetic material of the host organisms

Genetic Engineering (GE)

Modifying genes

What is GE used for

1. (a)improve the starter cultures

2. (b)produce the coagulating enzyme

Rennet

mixture of things that they use in cheese making

Renin

Purified rennet, pure form of enzyme

Genetically engineered starter cultures

Cultures with improved resistance to viruses, or improved enzyme activity

Recombinant chymosin

Bioengineered MO to replicate the gene for producing chymosin or rennin, used to coagulate milk and turn it into solid cheese.