Download - Production of Fermented foods and Beverages
Production of Fermented foods and Beverages
Biotechnology
Food BiotechnologyFermented food productsAlcoholic beveragesProduction of organic acidsProduction of amino acidsFood flavorsSingle cell protein
Lactic acid bacteria (LAB)A clade of Gram-positive, acid-tolerant, generally non-
sporulating rods or cocci
Usually found in decomposing plants and lactic products, produce lactic acid as the major metabolic end-product of carbohydrate fermentation.
This trait has, links LAB with food fermentations, as acidification inhibits the growth of spoilage agents.
Bacteriocins are produced by several LAB strains and provide an additional hurdle for spoilage and pathogenic microorganisms.
Generally recognized as safe (GRAS) status, due to their ubiquitous appearance in food and their contribution to the healthy microflora of human mucosal surfaces.
Lactic acid bacteriaCommon genera include
Lactobacillus Leuconostoc Pediococcus Lactococcus Streptococcus Aerococcus Carnobacterium Enterococcus Oenococcus Sporolactobacillus Tetragenococcus Vagococcus Weisella
Fermented food productsMilk Products
Fermented milk products have longer shelf life as compared to raw milk
Curd, buttermilk, yogurt and cheese require lactic bacteria
1. Butter and buttermilkMade from cream/curdFrom cream: soured by using Streptococcus cremoris or
S. lactis for the production of lactic acidLeuconostoc cremoris imparts characteristic flavor.By churning of cream/curd, butter is produced, leaving
buttermilk (liquid portion).
YogurtFermentation of milk by
Lactobacillus bulgaricus and Streptococcus thermophilus at 40-45 ◦C.
After 4 hrs, sufficient acidity is generated, good to enhance shelf life.
Flavour is imparted by accumulation of lactic acid and acetaldehyde produced by L. bulgaricus.
Commercially produced from pasteurized skimmed milk with added milk powder.
Cheese, the milk proteinCheese is a generic term for a diverse group of milk-based
food products. Cheese is produced throughout the world in wide-ranging
flavors, textures, and forms.Obtained by milk fermentationCoagulated mixture of proteins including casein Enzymetic process (rennin)
Cheese Whey
Lactic bacteria are used Renin may be obtained
From the calf stomach or Produced by microorganisms
Cheese VarietiesRipening of the cheese by
BacteriaMold
Soft cheese water content 50-80 %Ripened by surface growth
Semi-hard 40-45%Briefly cooked to lower the curd content
Hard cheese <40%Ripened with inoculation of spores of mold Penicillium
roguefortiiSalting cheese with sodium chloride
Fermented MeatsA delicacy in some middle-east countries.Fermentation of meat is carried out during curing by
lactic bacteria and Pedicoccus cerevisiae. Several types of salamis and sausages are produced
by fermentationGives flavourPreserves food
Leavening breadThe dough is fermented in the presence of sugar and yeast. Saccharomyces cerevisiae, the Baker’s yeast is mostly used
in leavening process.Production of Baker’s yeastNormally grown at 30◦C on molasses which is
Having low conc. of sugar (0.5-1.5%)Rich in mineral saltspH about 4.5
During fermentation, sugar content of molasses is meticulously controlled as higher conc. is deterrent to respiratory enzymes.
Yeast is collected through centrifugation.
Alcoholic BeveragesVinegar is an alcoholic liquid that has been allowed to sour.
Used to flavor and preserve foods. Ingredient in salad dressings and marinades. Used as a cleaning agent.
Two successive fermentations of grape juice, raisins or malt1. S. cerevisiae anerobically converts carbs to alcohol 2. Oxidative transformation of alcohol to acetic acid by
Acetobacter and Gluconobacter. Starting material includes
Citrus fruitsApple PearVegetables like potatoesMalted cerealsSugary syrups such as molasses, honey etc.
Production of organic acidsAcetic acidCitric acidGluconic acidLactic acidGibberallic acid
Citric acid production Citric acid is a weak organic acid.
It is a natural preservative/conservative and is also used to add an acidic, or sour, taste to foods and soft drinks.
Aspergillus niger is used for commercial production
Various strains of A. niger are used in the industrial preparation of citric acid and gluconic acid and have been assessed as acceptable for daily intake by the World Health Organisation.
Citric acid Uses CleaningCitric acid's ability to chelate metals makes it useful in
soaps and laundry detergents. By chelating the metals in hard water, it lets these cleaners
produce foam and work better without need for water softening.Citric acid is the active ingredient in some bathroom and
kitchen cleaning solutions. A solution with a 6% concentration of citric acid will remove
hard water stains from glass without scrubbing. In industry, it is used to dissolve rust from steel.
Citric acid can be used in shampoo to wash out wax and coloring from the hair.
Cosmetics and pharmaceuticals Citric acid is commonly used as a buffer to increase the solubility of
brown heroin. Single-use citric acid sachets have been used as an inducement to get
heroin users to exchange their dirty needles for clean needles in an attempt to decrease the spread of AIDS and hepatitis.
Citric acid is used as one of the active ingredients in production of antivirals.
Dyeing Citric acid can be used in food coloring to balance the pH level of a
normally basic dye. Citric acid is used as an odorless alternative to white vinegar for home
dyeing with acid dyes.
Foods, beverages, and personal care As a food additive, citric acid is used as a flavoring and preservative in
food and beverages, especially soft drinks. Citric acid can be added to e.g. ice cream as an emulsifying agent to
keep fats from separating, to caramels to prevent sucrose crystallization, or to recipes in place of fresh lemon juice.
Citric acid is used with sodium bicarbonate in a wide range of effervescent formulae, both for ingestion (e.g., powders and tablets) and for personal care.
Lactic AcidUsed as a preservative and also in leather and textile
industriesMicrobes involved in lactic acid production are
Lactobacillus delbrueckiiStreptococcus and Leuconostoc species.
Typical fermentation medium containsGluscose 10-15%Calciun carbonate 10%Ammonium phosphateTrace elemnets
Fermentation at 40-50 ◦C, pH 5.5-6.5 for 5-7 days
Production of Amino Acids Amino acids are consumed in a variety of markets.
The largest by volume is the food flavoring industry.
Monosodium Glutamate, alanine, aspartate, arginine are all used to improve the flavor of food.
L-lysine is directly produced from carbs by using Corynebacterium glutamcum, an auxotroph
MSG is produced by Arthrobacter, Corynebacterium and Brevibacterium
Food FlavoursAll kinds of preserved foods, such as soft drinks, milk
products and beverages are flavoured suitably.
The flavouring compounds are mostly purine nucleotides, including inosinic acid (IMP), and GMP.
Yeast is commercial source of flavouring compounds
Bacillus subtilis also enzymetically produces purine nucleotides through fermentation
Single-cell protein (SCP)SCP refers to the dried microbial cells or total protein
extracted from pure microbial cell culture (monoculture – Algae, bacteria, filamentous fungi, yeasts, etc…), which can be used as food supplement to humans (Food Grade) or animals (Feed grade).
SCP contains high protein content (60 – 80% of dry cell weight), fats, carbohydrates, nucleic acids, vitamins, and minerals.
It is also rich in essential amino acids such as Lys and Met.
SCP from Algal sourcesEconomical as algae utilize solar energy for growth.Chlorella and Spirulina (blue-green algae).Food from these sources contain 65% protein, 20%
carbohydrates and remaining 15% include lipids, fibre, pigments etc.
SCP from BacteriaCheap SCP is obtained from bacteria growing on cheap
agricultural and mineral wastesCellulomonas and Alcaligenes are mostly used
Fungi as source of SCPSaccharomyces, Candida utilis and Torulopsis can be grown
on wastes from paper industry and forestryRhodosporium sphaeroides produce a cell mass that
contains more than 50% lipids.
Advantages of using microorganisms for SCP production Protein synthesis is much more rapid than higher living
systems. Microbes have short generation time. Easily modifiable genetically for determining the amino acid
composition. Microbes have high protein content (7.12g protein
Nitrogen/100g dry weight). Microbes can be grown on media containing cheap sources of
C and N. Easy regulation of environmental factors for efficient yield.
DisadvantagesPossibility of contamination with pathological organisms in
SCP. Association of carcinogenic and other toxic substances with
SCP is often observed.Digestion of microbial cells is rather slow, and is frequently
associated with indigestion and allergy reactions. Food grade production of SCP is more expensive than other
sources of proteins, as it depends on the raw materials. SCP for human consumption is 10-12 times more expensive
thanSCP for animal feed.