Food additives

1. Food additives
• To improve nutritional value, flavor, color, and texture
• Some of these include
 proteins
 essential amino acids
 vitamins
 aroma compounds
 flavor enhancers
 salty peptides
 peptide sweeteners
 colors, stabilizers
 organic acids

2. Sources
• Bacteria
• Algae
• Yeast
• Molds
• Plant
• Mammalian

3. Recombinant DNA technology
1. identifying and isolating genes
2. synthesizing genes encoding a desirable trait
from plant and animal sources
3. from microorganisms that are difficult to
grow normally (gene isolation and
transformation)

4. Metabolic Engineering
• by which a desirable metabolite can be
produced in large amounts by a bacterial
strain
• Purify that metabolite
• GRAS-listed Compounds (regulatory agencies)

5. MICROBIAL PROTEINS AND FOOD
ADDITIVES
1. Single-Cell Proteins (SCPs)
2. Amino Acids
3. Nutraceuticals and Vitamins
4. Flavor Compounds and Flavor Enhancers
5. Colors
6. Exopolysaccharides (EPS)
7. Organic Acids
8. Preservatives

6. 1-Single-Cell Proteins (SCPs)
• Molds, yeasts, bacteria, and algae = rich in
proteins
• digestibility = ranges from 65 to 96%
• Yeast proteins = High digestibility (Preferred in
commercial production)
Examples:
Yeast strains : genera Candida,
Saccharomyces, and Torulopsis
Bacterial strains : genus Methylophilus

7. Microbial Proteins
Advantages
• not enough animal proteins to feed the growing human
population
• can be produced under laboratory settings =
overcoming land shortage and environmental
calamities (such as drought or flood)
• can be produced on many agricultural and industrial
wastes = help alleviate waste disposal problems
• can be a good source of B-vitamins, carotene, and
carbohydrates

8. Microbial Proteins
Disadvantages
• poor in some essential amino acids
(e.g.methionine) (supplementing microbial
proteins)
• can have high nucleic acid content (RNA and
DNA; 6 to 8%)
• In the human body, is metabolized to uric acid
(kidney stone formation)
• genetic manipulations

9. Microbial proteins (Current scenario)
• microbial proteins in human food = limited
use
• used as a protein source in animal feed
• use of microbial proteins = use of grains
as animal feed = can be used as human food

10. 2- Amino Acids
• cereal grains = deficient in essential amino acids
(methionine, lysine, and tryptophan)
• Supplement cereals
• Vegetable supplementation = vegetarians or for
developing countries

11. Production of Amino Acids
• from the hydrolysis of animal proteins
• Lactic acid bacteria that produce and excrete
large amounts of lysine
• Isolating high-producing strains of other
amino acids
• developing strains by genetic and metabolic
engineering

12. 3- Nutraceuticals and Vitamins
• vitamins are added to foods
• used as supplements
• Large market for vitamins, especially some B
vitamins and vitamins C, D, and E.

13. Sources of Vitamins
1. obtained from plant sources
2. synthesized
3. produced by microorganisms (few)
Examples:
• Vitamin C---produced by yeast (using cheese
whey)
• Microorganisms have also been a source of
vitamin D.
• Many are capable of producing B vitamins

14. Production of Vitamins
• Gene Cloning techniques???
• Multienzyme system
• metabolic engineering of strains of lactic acid
bacteria = used in dairy to produce high
amounts of folate and cyanocobalamin (B12)
• Strains of lactic acid bacteria = low-calorie
sweeteners (mannitol, sorbitol, and tagatose)

15. 4- Flavor Compounds and Flavor
Enhancers
• desirable aroma
• taste of foods
• strengthening of some flavors

16. Production of Flavor Compounds
Flavor Compound Flavor Produced by
Diacetyl Butter flavor Leuconostoc
Acetaldehyde Yogurt flavor Lactobacillus acidophilus
Nitrogenous and sulphur-
containing compounds
Sharp cheese flavor Lactococcus lactis
Propionic acid Nutty flavor Dairy Propionibacterium
Pyrazines Roasted nutty flavors Strains of Bacillus subtilis
and Lac. Lactis
Terpenes Fruity or flowery flavors Some yeasts and molds

17. Natural flavors from plant sources
• Very costly
• Limited amounts are available
• Extraction process is very elaborate
• Natural Vanilla flavor(now obtained from
plants)
• If produced by microorganisms, may cut the
cost to only one tenth or less

18. Natural flavors from fruit sources
• Costly
• Large amount of fruits are wasted
• Production of many of these flavors by
microorganisms through recombinant DNA
technology is being studied.

19. Flavor Enhancers
• used to strengthen the basic flavors of foods
Compound Flavor Produced by
Monosodium glutamate
(MSG)
enhances meat flavor Corynebacterium
glutamicum and
Micrococcus glutamicus
5nucleotides (such as
inosine monophosphate
and guanosine
monophosphate)
give an illusion of
greater viscosity and
mouth feel in foods such
as soups
Bac. subtilis

20. Flavor Enhancers
• Small peptides (lysylglycine) have strong salty
tastes.
• They can be produced by rec. DNA tech. and used
to replace NaCl.
• Sweet peptides (monellin and thaumatins) from
plant sources, can also be produced through gene
cloning.
• Aspartame (dipeptide sweetener) is produced
synthetically

21. Flavor Enhancers--- Recent Advance
• By metabolic engineering, strains of lactic acid
bacteria have been developed that can
produce large quantities of
diacetyl (for aroma of butter)
acetaldehyde (for aroma of yogurt)
a-ketoglutarate (to produce cheese flavor)

22. 5- Colors
• bacteria, yeasts, and molds produce different
color pigments.
Color Pigment/
Comound
Produced by Usage
Red (Astaxanthine) Phaffia sp. (a yeast
species)
gives the red color
to salmon, trout,
lobster, and crabs
Red Monascus sp.
(yeast)
used to make red
rice wine

23. Color Pigment Production
• May involve multistep reactions
• Recombinant DNA techniques may not be
economical.
• Color Pigments can be produced by the plant
cell culture technique.

24. 6- Exopolysaccharides (EPS)
• used in food systems as stabilizers and texturizers
• Plant origin (microbial sources)
• Lactic acid bacteria (Streptococcus thermophilus, Lab.
rhamnosus, Lab. helveticus, Lab. casei, and Lac. Lactis)
• EPS that contain units of glucose, galactose, rhamnose,
mannose, and other carbohydrates
• used to produce fermented dairy products
1. with better consistency and texture (in yogurt and butter
milk)
2. to hold moisture in low fat-high moisture cheeses (in
mozzarella cheese)

25. EPS
EPS Produced by Usage
Dextran Leuconostoc
mesenteroides while
growing in sucrose
used as a stabilizer in ice
cream and
confectioneries
Xanthan gum Xanthomonas campestris used as a stabilizer
Introducing lactose-hydrolyzing genes in Xanthomonas species
can enable it to grow in whey to produce the stabilizer
economically.

26. 7- Organic Acids
• Organic acids and their salts are used in foods to
improve taste (flavor and texture) and retain quality
• Production of ascorbic acid by yeasts and its use as a
vitamin supplement
• Ascorbic acid is also used in some foods as a reducing
agent to maintain color (to prevent color loss by
oxidation). It also has an antibacterial action
• Citric acid is used in many foods to improve taste and
texture (in beverages) and stabilize color (in fruits). It
also has some antibacterial property. Citric acid is
produced by the mold Aspergillus niger.

27. 8- Preservatives
• Bacterial cells of lactic acid bacteria (several
organic acids produced by them)
• Their bacteriocins
• used to control spoilage and pathogenic
bacteria in foods