Reading reminder: I have referred to as much information as possible, but due to insufficient knowledge, there may be some errors, please be careful when applying, please refer to GB 2760-2014 for more.
1
preservative
Chemicals that are added directly to food and only play an antiseptic effect
First, the spoilage of food
1. Meaning
Generally refers to the various changes in food composition and sensory traits caused by microbial effects under the influence of certain environmental factors.
Fish, meat rot, rancidity of oil, rot of vegetables and fruits, grain mildew, etc
2. Causes and conditions of food spoilage
1) The composition and nature of the food itself
Enzymes, food nutrients, moisture, PH and osmotic pressure
PH6 is best suited for microbial proliferation, with a PH < 4.5 bacteriostatic
The smaller the water activity AW, the less conducive it is to microbial growth.
AW < 0.7, and generally microorganisms cannot reproduce.
2) Microorganisms (bacteria, mold, yeast)
Microbial enzymes break down food ingredients to produce adverse organoleptic traits.
3) Environmental conditions
T 20-35°C, PH 6-7, > 80% RH
Ultraviolet rays and oxygen also have an impact on food spoilage.
3. Chemical processes and products of food spoilage
1) Protein decomposition in food: fish, poultry, eggs and milk
2) Fatty acid defeat: edible oil and foods with high oil content
3) Decomposition of carbohydrates: grains, vegetables, fruits
4. The significance of food hygiene in spoiled and spoiled food
A． Poor sensory stimulation
B． Food ingredients are severely damaged
C. Adverse reactions to the human body, food poisoning may occur
Second, an overview of anti-corrosion methods
1. Antiseptic methods for processing food, fruits and vegetables:
Physical method: heating, cooling, refrigeration, radiation, ultraviolet, dry, pickled
Chemical: A method that uses chemicals to inhibit or kill microorganisms
The advantages of chemical methods: less investment, fast results, no need for special equipment and equipment, no change in the organizational form of food
2. Type
Preservatives in a broad sense include bacteriostatic agents and fungicides.
The ingredients are divided into inorganic and organic preparations.
The use is divided into food preservatives and fruit and vegetable preservatives.
China allows the use of 32 kinds:
Benzoic acid and its sodium salts / propionic acid and its sodium salts, calcium salts / monocaprylate glycerides / parabens and their sodium salts (/ dimethyl dicarbonate / 2,4-dichlorophenoxyacetic acid / sulfur dioxide, potassium metabisulfite, sodium metabisulfite, sodium sulfite, sodium bisulfite, sodium hyposulfite / carbon dioxide / ε - polylysine / ε - polylysine hydrochloride / biphenyl ether (also known as diphenyl ether / sulfur / natamycin / lysozyme / cinnamal / streptococcus lactate / sorbic acid and its potassium salt / sodium biacetate (also known as sodium diacetate )/Dehydroacetic acid and its sodium salts (aka dehydroacetic acid and its sodium salts) / steady state chlorine dioxide / sodium nitrate, potassium nitrate / sodium nitrite , potassium nitrite / disodium edta / liquid carbon dioxide (coal gasification method) / sodium acetate (aka sodium acetate / ethoxyquine / dimethyl dicarbonate (aka virgolin)
Third, the conditions that preservatives should have
1, the nature is stable, in a certain period of time the chemical structure is unchanged and effective, the use of neutral and in the body (decomposition or non-decomposition) non-toxic
With the development of science and technology, especially the progress of analysis and detection methods, people realize that some preservatives used in the past, such as borax, formaldehyde, salicylic acid and coke diethyl esters, can also bring certain harm to the human body while preserving food and have been banned.
2, itself is not irritating and odorous
That is, preservatives have no effect on the flavor and taste of food
3. There is still bacteriostatic effect at low concentrations
That is, preservatives should have efficient properties, which can reduce the amount of preservatives used and ensure that consumers mainly consume food, not preservatives.
4. Reasonable price and easy to use
That is, it has little impact on the manufacturing cost of food, and it does not require special equipment and operation when using it
Fourth, the combination of preservatives and physical antiseptic methods
1. Combination of anti-corrosion and heating methods
Practice has proved that the temperature required to kill microorganisms in the presence of preservatives is much lower and the time required is much shorter than when no preservatives are present.
Sorbic acid or benzoic acid combined with heating method can shorten the inactivation time of yeast by 30 to 80%
Table 1 Effect of parahydroxybenzoic acid addition on yeast inactivation
2. Preservatives and refrigeration treatment
Freezing can limit the proliferation of microorganisms, and the addition of preservatives can generally extend the shelf life of food frozen and refrigerated.
At room temperature, the amount of preservatives used that are not enough to prevent food spoilage is sufficient under freezing conditions.
3. Preservatives and irradiation treatment
Experiments have found that there is a synergistic effect between preservatives and irradiation, such as the use of sorbic acid in apples, vegetables, juices, cheese and other dairy products, which can reduce the irradiation dose of irradiation preservation treatment, which is conducive to reducing and preventing the side effects of irradiation.
Fifth, several factors affecting the effect of preservatives
1、pH
For acid-based preservatives, in aqueous or aqueous solution systems, their antiseptic effect mainly relies on the action of undiscovered acids on microorganisms, and the dissociated H+ effect is small. Therefore, when using such preservatives, it is necessary to increase the proportion of unresponsed acids as much as possible within the scope of the food system license to increase the antiseptic effect and reduce the amount of preservatives.
2. Moisture activity (Aw)
Adding electrolytes or soluble substances to the water and reaching a certain concentration can reduce the Aw of the system.
The various microorganisms must be above their respective AW to grow normally. According to the different types of microorganisms that are prone to growth in different food systems, the Aw of the food system is controlled to achieve the purpose of inhibiting the growth of microorganisms. This measure is very effective for certain foods of high AW.
Table 2 Minimum AW allowed for microbial growth
3. Dissolution and dispersion of preservatives
When using preservatives, it is necessary to deal with the specific situation of food spoilage
Spoilage occurs outside the food (such as fruits, potatoes, frozen foods, etc.): as long as the preservatives are evenly dispersed on the surface of the food
Spoilage occurs inside food (e.g. canned, baked goods, beverages, etc.): preservatives are required to be evenly dispersed in the food. At this time, we should pay attention to the dissolving and dispersing characteristics of the preservative
Easily soluble in water: water as a solvent
Easily soluble in organic solvents: generally use different concentrations of edible alcohol and other solvents
Water, ethanol insoluble or insoluble:
I. Disperse with a dispersant
II. Chemically modified preservatives to increase solubility
4. Preservative addition time
If the general preservative is necessary, it should be added in time, so that the effect is good and the dosage is small
If the degree of food contamination is heavier when the preservative is added, the worse the antiseptic effect. If the food has deteriorated, the addition of any preservatives will not help, the process is irreversible.
note:
Be sure to ensure that the food is under good hygienic conditions to add preservatives, that is, the addition time should be in the induction period of microbial growth, if it has entered the logarithmic proliferation period, the antiseptic effect will be greatly reduced.
5. The combination of preservatives
All kinds of preservatives have a certain range of effects, and no one preservative can resist all the spoilage microorganisms that may appear in food.
From medical knowledge, many microorganisms will develop resistance to certain preservatives
Both of these conditions reduce the effectiveness of preservatives. In order to compensate for the shortcomings of a single use of preservatives, preservatives of different ranges of action can be used together. The combined use of preservatives expands the scope of action and enhances the antimicrobial effect.
Examples of commonly used preservatives:
1. Benzoic acid (Benzoic Acid)
[Alias]: Benzoin acid
[Chemical Structure]
[Properties]
This product is white with fluorescent flakes or needle-like crystals, light, odorless or slightly with the odor of benzoin or benzaldehyde. The nature of this product is stable, but it is hygroscopic. The specific gravity is 1.2659, the boiling point is 249.2 °C (0.1 MPa), the melting point is 122.4 °C, and the sublimation begins at 100 °C, which is easy to volatilize with water vapor under acidic conditions. Easily soluble in ethanol, chloroform, ether, non-volatile oils and volatile oils. Slightly soluble in hot water (4.55g/100ml, 90°C), slightly soluble in hexane, pH 2.8 (25% aqueous solution).
[Toxicological basis]
The oral LD50 of benzoic acid rats was 2530 mg/kg body weight.
FAO/WHO (1994) defines ADI at 0 to 5 mg/kg body weight
Benzoic acid does not accumulate in the human body, and most of it binds to glycine to form equine (benzoylglycine) within 9 to 15 hours, which is excreted through the urine.
However, there are still reports of the harmfulness of benzoic acid, when mice consume 400 mg/kg body weight per day, after 17 months, rats 40 mg/kg body weight per day, after 18 months, will have the effect of hindering their growth.
In food preservatives, the use of benzoic acid and its salt is relatively safe, when the amount of use within its specified range, no toxicity has been seen.
[Use]
GB2760-2014 stipulates:
0.2g/kg: carbonated beverages; special purpose beverages.
0.4g/kg: Prepared sake.
0.5g/kg: Candied fruit.
0.6 g/kg: Compound seasoning.
0.8g/kg: cider; candy other than gum-based candy.
1.0g/kg: fruity soda, jam (except canned), pickled vegetables, flavored syrup, vinegar, soy sauce, sauce and sauce products, semi-solid compound seasoning, liquid compound seasoning (excluding 12.03, 12.04), fruit and vegetable juice (pulp) drinks, protein drinks, tea, coffee, plant (class) drinks, flavored drinks.
1.5g/kg: Gum-based confectionery.
2.0g/kg: Concentrated fruit and vegetable juice (pulp) (for food industry only).
If benzoic acid is used at the same time as sodium benzoate, the maximum amount of benzoic acid is not exceeded.
The most suitable bacteriostatic pH of benzoic acid is 2.5 to 4.0, and the minimum concentration of bacteriostatic is 0.05 to 0.1%, but its solubility is reduced in the acidic solution, so the bacteriostatic activity cannot be improved by increasing acidity alone
Under acidic conditions, benzoic acid can volatilize with water vapor, so it should be added later in food heating
Benzoic acid and its salts are mainly used in beverages, syrups, juices, jams, soy sauce and other products
Example 2: Streptococcin lactate (Nisin)
[Alias]: Streptomycin, Streptopeptide
[Main composition]: Streptococcus lactate is a polypeptide antibiotic substance produced by Streptococcus lactate, which is composed of 34 amino acids. Its amino terminal is isoleucine, the carboxyl terminal is lysine, and the molecular weight is 3500. The active molecules are often dimers and tetramers, and their molecular weights are 7000 and 14000, respectively
[Properties]:
Streptococcin lactate is very stable at room temperature and under acidic heating conditions, such as below pH 2.0, heating to 115.6 °C 30min, still very stable. At a pH of 5, it loses 40% of its vitality. When the pH is 9.8, its vitality loss is more than 90%.
The water solubility of streptococcin lactate is closely related to the pH. At low pH, it is more water soluble. When the pH is 2.5, the solubility is 12%, and at pH 5.0, it is 4%. It is virtually insoluble under neutral and alkaline conditions. The best solvent for streptococcin lactate is 0.02N hydrochloric acid.
[Functionality]:
Streptococcin lactic acid can effectively inhibit bacteria and spores that cause food spoilage, extend the shelf life of food, reduce sterilization temperature, shorten sterilization time, improve food quality, reduce energy consumption, replace or partially replace chemical preservatives, and meet the needs of producing healthy foods.
Canned food in the acidophilus bacillus, pyrolyzyls Clostridium, Clostridium heliobacterium, Clostridium botulinum, Clostridium pasteurella, Lactobacillus coagulans, Bacillus multimuscularis, Bacillus softening, etc. are very sensitive to streptococcus lactic acid, generally 10 to 50ppm is effective.
However, the antibacterial spectrum of streptococcin lactate is relatively narrow, which can only kill or inhibit G+ bacteria, especially bacterial spores, and has no effect on negative bacteria and yeasts, such as Staphylococcus aureus, streptococcus hemolyticus, Clostridium botulinum, etc. in dairy products; Lactobacillus in beer, Mingococcus.
[Toxicological basis]:
LD50: Male rats orally 14.70 g/kg body weight
ADI: 0 to 33000 IU/kg body weight
Streptococcus lactate is a polypeptide substance, which is quickly decomposed into amino acids by proteolytic enzymes in the digestive tract, does not change the normal flora in the intestine, and causes resistance to other commonly used antibiotics, and will not cross-resist with other antibiotics, and the safety is very high.
[Use]:
Streptococcin lactic acid has the characteristics of non-toxicity, small dosage, easy to use, good antiseptic effect, low price, etc., and is widely used in dairy products, meat products, canned food, soy sauce, beverages, sauces and sauce products and other foods.
Precautions for the use of preservatives
Understand the minimum bacteriostatic concentration of the antibacterial spectrum of the preservative used and the putrefactive bacteria carried by the food, so that it can be targeted.
Understand the physico-chemical properties of preservatives, such as pH conditions.
Understand food processing, storage conditions, duration and the impact on preservative effects during these processes so that preservatives remain effective.
2
antioxidant
First, the concept
Definition: Is to prevent or delay the oxidation of food, improve the stability of food and extend the storage period of the substance.
The conditions that antioxidants should have
For food has excellent antioxidant effect, the dosage is appropriate.
It is non-toxic, harmless when used and decomposed, and does not produce strange smells and colors on food.
Good stability in use, easy to analyze and detect.
Easy to make and inexpensive.
classify:
source
Natural: Tocopherols, tea polyphenols
Synthetic: Butyl hydroxyanisole (BHA), ascorbic acid and its salts
How to add
Dissolve in addition: water soluble: iso-ascorbic acid and its salts; oil soluble: BHA, dibutyl hydroxytoluene (BHT), terbutyl hydroquinone (TBHQ), propyl gallate (PG)
Materials are not added in contact: small packages of oxygen scavengers, sprayed on the packaging
Follow the mode of action
Free radical absorbers, metal ion chelating agents, oxygen scavengers, peroxide decomposers, enzyme antioxidants, ultraviolet absorbers, single-line oxygen quenching agents, etc.
Second, the mechanism of action
1. Consume oxygen inside food and in the environment
Also known as deoxidizer, in the process of sealing food packaging, at the same time sealing a substance that can remove oxygen.
Commonly used are: iron hyposulfite, calcium hydroxide, iron powder, enzymatic glucose, Vc and the like.
1) Composition of the deoxidizer
Main agent: deoxygenation. Such as cast iron powder, the particle size should be small.
Excipients:
Assisted co2 production. Such as sodium carbonate;
catalyst. For example, metal halides can improve the reaction speed of the deoxidizer. Commonly used NaCl;
Binders. Control the deaeration speed and improve the air permeability of the composition. Commonly used insoluble and inactive substances such as silica, activated carbon, etc.
2) Deoxidizer
The most commonly used are iron and sodium dithionite deoxidizers:
A. Iron deoxidizer: 1g of iron oxidized into iron oxide requires about 1500mL of air, and the effect is remarkable.
Fe+2H2O——Fe(OH)2+H2↑
2Fe(OH)2 +12O2 +H2O——Fe2O3·3H2O
Fe +O2 +H2O——Fe(OH)3
B. Sodium liandisulfite
2Na2S2O4+2NaHCO3+O2——Na2SO4+Na2SO3+H2O+CO2↑
Add water and activated carbon as excipients.
3) Deoxygenation capacity
According to the speed of its deoxygenation, it can be divided into quick-acting (within 1 day), slow-acting (4-5 days) and so on.
The deoxidation capacity requires that the oxygen content of the sealed container is finally reduced to 0.1 to 0.2%. Generally, 400mL of air at 20 °C, the residual oxygen can be reduced to less than 0.2 after 2 days with 1g of oxygen absorber.
Commonly used in fresh food products such as meat products, fruits, oil products, aquatic products, cakes, grain and so on.
Such as pizza, 40% N2 and 60% CO2 packaging, stored at 30 °C for 2 to 3 days, with oxygen absorber for 14 days without mold.
2. Block the chain reaction of automatic oxidation of grease
1) Automatic oxidation reaction of oils and fats:
A. Chain initiation stage: unsaturated fatty acids (RH) in oils and fats dehydrogen (H·) and produce free radicals (R· ), free radicals and oxygen to form peroxidated free radicals.
B. Chain growth stage: Peroxidated radicals make new unsaturated fatty acids (RH) into hydroperoxides, and new free radicals, and so on, until the unsaturated fatty acids are oxidized into hydroperoxides and further decomposed into other products.
Degradation of hydroperoxides, polymerization to form odorous substances
2) Free radical inhibitors
Provide hydrogen with R· and ROO· action, the formation of the original lipid molecules (RH) and hydroperoxide (ROOH), itself to form an inactive oxidant free radical, thereby interrupting the free radical reaction.
Antioxidants belonging to this type of mechanism of action are: butyl hydroxyanisole (BHA), dibutyl hydroxytoluene (BHT), propyl gallate (PG), tert-butylhydroquinone (TBHQ);
Tea polyphenols (TP), vitamin E, etc.
This type is also called free radical adsorbent.
Natural antioxidant
3. Inhibits the activity of oxidase
Such as L-ascorbic acid, sulfites.
4. Chelate metal ions to eliminate their catalytic activity
Such as phytic acid (inositol hexaphosphate), lecithin (phosphatidylcholine, referred to as PC. ）
This type of antioxidant is also called metal ion chelating agent.
5. Synergist of antioxidants
Generally, it is an acidic substance with metal ion chelating, such as citric acid, phosphoric acid, ascorbic acid and the like.
Synergy principle: It has a passivation effect on metal ions that promote oxidation. It may also be to regenerate antioxidants.
Second, antioxidant examples
There are a total of 38 kinds of antioxidants allowed in China.
4-Hexylresorcinol/D-Isocorbic acid and its sodium salts/tea polyphenols/tea polyphenol palmitate/theaflavin/butyl hydroxyanisole (BHA)/dibutylhydroxytoluene (BHT)/sulfur dioxide, potassium metabisulfite, sodium metabisulfite, sodium sulfite, sodium bisulfite, sodium hyposulfite/licorice antioxidant/potassium metabisulfite/sodium metabisulfite/ascorbyl acid (aka vitamin C)/calcium ascorbate/sodium ascorbate/ascorbyl palmitate (enzymatic) / Phospholipids / Dilaurate thiodipropionate / Propyl gallate (PG) / Rosemary extract / Rosemary extract (supercritical / Hydroxystearin (aka stearyl oxide) / Calcium lactate / Sodium lactate / Sorbic acid and its potassium salt / Tbutyl hydroquinone (TBHQ / "Vitamin E (dl-α-tocopherol, d-α-tocopherol, / mixed tocopherol concentrate)" / sodium sulfite / disodium edta/calcium disodium edta/phytic acid (aka inositol hexaphosphate), sodium phytate / Bamboo leaf antioxidants
Example 1: Butyl Hydroxy Anisol
[Overview]
Tert-butyl-4-hydroxyanisole (anisole), or BHA for short.
Molecular formula C11H16O2, relative molecular mass 180.25,
[Properties]
BHA has a peculiar phenolic odor and a pungent odor.
Mixtures of 3-BHA and 2-BHA, generally 3-BHA with a content of more than 90%, are sold in lump or flake form.
Melting point 57 °C ~ 65 °C, with different mixes,
Insoluble in water, the solubility (25 ° C) in several solvents and oils is: 50% propylene glycol; acetone 60%; ethanol 25%; peanut oil 40%; cottonseed oil 42%; pig fat 30%.
It is fairly stable to heat and is not easily destroyed under weakly alkaline conditions, which may be one of the reasons why it is effective in baked goods.
[Toxicity]
LD50 2.2~5g/kg(bw) rats, (orthopal).
ADI 0～0.5mg/kg （bw） （FAO/WHO，2001）
[Use]
A. Scope of use
a) Application in greases
BHA has a strong antioxidant effect on animal fats:
The use of BHA alone increases the oxidation stability of lard from 4h to 16h.
Used in conjunction with the synergist citric acid, it can be increased to 36h.
If another chelating agent such as citric acid is added to the mixture of BHA with PG or BHT, it will be more effective.
BHA has a smaller effect on vegetable oils than animal oils.
b) Application in meat products
For meat products, 0.01% BHA stabilizes the color of raw beef and inhibits the oxidation of lipids, and prevents the fading and deterioration of various dried sausages.
c) Application in spices and nuts
It can stabilize the color of paprika and prevent oxidation of walnuts, peanuts, etc.
Add to roasting oil and salt to preserve the flavor of baked goods and salty peanuts.
d) Application in candy and baked goods
BHA can be used at the temperature of frying or baking, and in the process enters the food with the oil, thus exerting antioxidant effects on the food.
Used to compress biscuits and biscuits with high fat content, it can effectively prevent oxidation.
e) Applications in food packaging materials
BHA has a certain degree of fumigation, so it can be applied in food packaging materials and has an antioxidant effect on food.
It can be applied to the inside of the packaging material, or it can be filled with antioxidant vapor in the bag, or the antioxidant can be sprayed on the wrapping paper by spraying.
The dosage is 0.02% to 0.1%.
B. Precautions for use
There is no synergistic effect between 3-BHA and 2-BHA.
The product BHA contains more 3-BHA, and its antioxidant effect is enhanced with the increase of its concentration, but after the concentration is increased to 0.02%, the antioxidant effect is no longer enhanced.
Example 2: Dibutylhydroxytoluene BHT
2,6-Di-tert-butyl-p-cresol, 3,5-di-tert-butyl-4-hydroxytoluene, BHT for short. Molecular formula C15H24O, relative molecular mass 220.36.
The melting point is 69.5 °C ~ 70.5 °C (pure product is 69.7 °C), and the boiling point is 265 °C.
It is fairly stable against heat and volatilizes with water vapor when heated.
Contact with metal ions, especially iron ions, does not show color, and the antioxidant effect is good.
Insoluble in water, glycerin and propylene glycol, soluble in many solvents,
Its solubility is: ethanol 25% (20 °C), soybean oil 30% (25 °C), cottonseed oil 20% (25 °C), lard 40% (40 °C).
LD50 890 mg/kg (bw) (rat, orally).
ADI 0~0.3mg/kg (bw)
Compared to BHA, the toxicity is slightly higher.
B. Scope of use
Edible fats, fried foods, biscuits, instant noodles, nuts, canned food, cured meat products and cereals for breakfast
The maximum use is 0.2g/kg.
When BHA is mixed with BHT and PG, the total amount of BHA and BHT shall not exceed 0.10g/kg, and the PG shall not exceed 0.05g/kg.
When BHA is mixed with BHT, the total amount must not exceed 0.2g/kg (the amount used is measured in fat).
It can also be used as gummy ingredients.
a) Application in greases
In vegetable oils, BHT, BHA and citric acid can be used to form a mixture with a ratio of 2:2:1.
For animal oils, BHT is more effective than BHA, using concentrations of 0.005% to 0.02%.
b) Application in meat products
For meat products, BHT can effectively delay the catalytic oxidation of metheme in pork.
Using a mixture of BHT and PG is more efficient than using BHT alone.
c) Application in baked goods
Effectively prevent the oxidative rancidity of the oil in the biscuit and prolong the shelf life.
The amount of addition is 0.1g/kg, which is dissolved in oil when used.
d) Application in nuts
For tree nuts, a mixture of BHA and BHT is effective in stabilizing shelled foods such as walnuts and peanuts.
e) Application in packaging materials
BHT can also be added to the packaging of baked goods, quick-frozen foods and other foods such as paper or plastic film, the amount of which is 0.2 to 1g BHT per kilogram of packaging material.
BHT has less protective effect on oils and fats used in fried foods and does not have enough stabilizing effect on margarine during storage.
It is rarely used alone.
BHT is mixed with BHA or TBHQ, but it has no synergistic effect on PG.
Example 3: VE (tocopherol)
CNS: 04.016
Abbreviated VE. Functional category, classified as a nutritional enhancer.
Odorless clarification of viscous liquid.
Light resistance, ultraviolet rays, radiation linearity resistance is also strong - relative to BHA, BHT. This is important for food packaged in transparent materials – especially for cooking oil.
High thermal stability – relative to BHA;
Insoluble in water, easily soluble in ethanol.
Can be mixed freely with grease.
LD50 3000 mg/kg (bw) (rat, orally).
ADI 0～2mg/kg （bw）（FAO/WHO，2001）。
Example 4: Ascorbic acid (vitamin C)
[Overview] Chemical Structural Formula
CNS：04.014
[Properties]
It has a sour taste, a melting point of about 190 ° C, and gradually turns brown after being exposed to light.
In the aqueous solution, its content decreases rapidly, and the pH is more stable at 3.5 to 4.5.
lg is about soluble in 3mL water, 30mL ethanol, insoluble in chloroform, ether and other organic solvents.
It is reductive and easily oxidized to dehydroacorbic acid.
[Dosage, range]
Applications in fruits and vegetables
Vitamin C is very effective in inhibiting browning of fruits and vegetables during processing.
In canned juices such as apples, pears, figs and grapes, vitamin C is a potent antioxidant.
Vitamin C is used in various fruit juices during processing and storage.
During fruit juice processing, vitamin C is added to the pulp of apples, pears, grapes, etc., which can stabilize their color and taste.
Vitamin C can be used to inhibit the fading of a variety of processed vegetables, such as peeled potatoes, brine pickles, canned mushrooms, carrots, beets, and cauliflower. In canned mushrooms, vitamin C is added with chelating agents such as EDTA or citric acid is beneficial. Propyl gallate in combination with vitamin C effectively protects the pungent odor of horseradish powder.
Example 5: Phytic Acid
[Overview] CNS：04.006
Inositol hexaphosphate, referred to as PA, molecular formula C6H18O24P6, the relative molecular mass is 660.08.
Light yellow to yellow viscous liquid, easily soluble in 95% ethanol, glycerin and acetone, slightly soluble in water, ethanol and methanol, insoluble in benzene, chloroform and ether.
The aqueous solution is strongly acidic, and the pH of the aqueous solution is 0.40 at a concentration of 1.3% and 2.26 at 0.13%.
It is easy to decompose in case of high temperature
For shrimp preservation, it can be used in an appropriate amount according to production needs, and the allowable residue is ≤20mg/kg; for edible oils, fruit and vegetable products, beverages and meat products, the maximum use amount is 0.2g/kg.
a. Application in grease
Antioxidants of vegetable oils, such as adding 0.01% to vegetable oils such as soybean oil, are very effective.
b. Application in fruits and vegetables, beverages
For the preservation of fruits and vegetables, fruits and vegetables can be impregnated in 1% phytic acid solution or sprayed evenly with phytic acid solution; used for cool drinks and milk drinks to improve color, prevent fruit juice from fading, and improve shelf life. The amount of addition is 0.02% to 0.05% (accounting for the mass fraction of raw materials), and it is directly added to dissolve when used.
Third, the use of antioxidants
1. Toxicity analysis of antioxidants
TBHQ ADI is tentatively set at 0.2 mg/kg (bw) because its mutagenic effect cannot be ruled out due to the lack of sufficient long-term experimental results, so some countries do not allow its use.
BHA ADI = 0.5 mg/kg (bw), fed to 2% BHA feed in mice is carcinogenic, but has no effect on pigs, dogs and monkeys.
BHT ADI = 0.125 mg/kg (bw), and carcinogenic reports have been reported with 1% to 5% of mice fed, equivalent to 50 mg/kg (bw).
2. Physical properties
3. Characteristics of the use of antioxidants
The antioxidant effect on animal fats is stronger than that of BHT and the antioxidant effect of unsaturated vegetable oils is weaker.
Resistant to high temperature frying
Has a certain degree of fumigation. But there is a peculiar smell.
Can be used alone or shared with other antioxidants.
It can be used for grease, fried food dried fish, biscuits, instant noodles, nuts, etc.
Disabled in the United States and Japan
Synergistic effect of antioxidants
3
Emulsifier
I. Overview
Definition: A substance that improves (reduces) the surface tension between the constituent phases in an emulsion to form a uniform dispersion. A class of substances with two groups, hydrophilic and lipophilic, can make the oil and water in food appear uniform and stable in the state of mixed emulsion.
Source: Natural and synthetic
Emulsification system properties: oil-in-water (o/w) type and water-in-oil (w/o) type
Dissociation characteristics: anionic type (such as sodium stearoyl lactate, etc.) and non-ionic type (most emulsifiers)
There are 48 emulsifiers allowed in China:
D-Mannitol / Ammonium Phospholipid / Propylene Glycol / Propylene Glycol Fatty Acid Ester / Mono, Diglyceryl Fatty Acid (Oleic Acid, Linoleic Acid, Palmitic Acid, Behenic Acid, Stearic Acid, Lauric Acid, Linolenic Acid) / Modified Soy Phospholipid / Glycerin (aka Glycerol) / Pectin / Propylene Alginate / Monoglycerides Succinate / Polyglyceryl RicinolAte (PGPR) / Polyglyceryl Fatty Acid / Polyoxyethylene (20) Sorbitan Monolaurate (aka Twain 20), Polyoxyethylene (20) Sorbitan Mono Palmitate ( Also known as Tween 40), polyoxyethylene (20) sorbitan monostearate (aka Tween 60), Polyoxyethylene (20) sorbitan monooleate (aka Twain 80) / polyoxyethylene xylitol anhydride monostearate / carrageenan / soluble soy polysaccharide / sodium caseinate (aka sodium caseinate) / phospholipid / maltitol and maltitol liquid / enzymatically dissolved soy phospholipid / xyrrhione glycerides / xylitol alcohol monostearate / glyceryl citrate / hydroxypropyl starch / hydrogenated rosin glycerides / calcium lactate / lactic fatty acid glycerides / lactitol (aka 4-β-D pyranyl galactose-d-sorbitol) / Sorbitan monolaurate (aka Span 20), Sorbitan Monopalmitate (aka Sorbitan 40), Sorbitan Monostearate (aka Sorbitan 60), Sorbitan Tristearate (aka Stapan 65), Sorbitan Monooleate (aka Stapan 80) / Sorbitol and Sorbitol Liquid / Monobiglyceride/Caprylate/Caprylate/Sodium Caprylate/Sodium Starch Octenyl Succinate/Acetylated Mono,Diglyceryl Fattyrate/Calcium Stearate/Potassium Stearate/Magnesium Stearate/Sodium Stealactylate// Calcium stearoyl lactate / saponin bark extract / sucrose fatty acid ester /
HLB value of emulsifier and related properties
The hydrophilytyand Lipophilyty Balance (HLB value) is generally used to indicate the difference in emulsifier emulsification capacity
100% lipophilicity: HLB = 0
100% hydrophilicity: HLB = 20
Second, the application of emulsifiers
1. Emulsification
Prevent food oil and water separation, prevent sugar and grease from frosting, etc. Such as chocolate, ice cream, cream, mayonnaise.
2. It has a good conditioning effect on starchy foods
Because it can be combined with amylose to form a stable complex, it is difficult to crystallize and precipitate amylose, which plays a role in delaying starch aging, and can form hydrogen bonds or couplings with lipids and proteins in flour, which strengthens the network structure of the dough.
Such as for bread, pastries, biscuits, noodles and other starchy foods
3. Adjust the viscosity
Easy to produce operations. Such as chewing gum, chocolate, biscuits.
4. Stabilize bubbles and inflate
Emulsifiers containing saturated fatty acids have a stabilizing effect on foaming. Such as ice cream
5. Wetting and dispersing effect
This effect can be used in foods such as milk powder, cocoa powder, malt milk, instant coffee, and powdered beverage infusions to improve solubility in cold and hot water.
6. Control crystallization
The emulsifier can be used as a grease crystallization regulator to control the crystalline structure of oils and fats in food to improve the taste quality of food.
Such as margarine, ice cream, chocolate.
7. Deemulsification - defoaming effect
In some processes, the opposite emulsifier can be added to disrupt the balance of the emulsion, and the emulsifier containing unsaturated fatty acids can be used as a defoamer for dairy processing.
8. Solubilization effect
Emulsifiers with HLB values greater than 15 can be used as solubilizers for fat-soluble pigments, fragrances, and enhancers.
9. Anti-stick effect
The emulsifier can form a protective film outside the crystals of the sugar, which plays a moisture-proof role.
10. Antibacterial, freshness preservation effect
Sucrose ester has certain antibacterial properties, can be used as egg, fruit, vegetables and other fresh-keeping film emulsifiers, improve its antibacterial properties; natural emulsifier ophosphate esters also have antioxidant effects.
Third, the role of emulsifiers in the main foods for example
1. Bread, cakes
A. Prevent the hydrophobic effect of amylose in flour, thereby preventing aging and rejuvenation;
B. Reduce the viscosity of the dough for easy handling;
C. Promote the formation of gluten tissue;
D. Improve foaming and make stomatals dispersed and dense;
E. Promote shortening emulsification, dispersion, improve tissue and taste.
In baked goods
Emulsifiers strengthen the gluten network structure, prevent hardening caused by oil-water separation, increase toughness and tensile strength (e.g. noodles) to maintain its softness, inhibit water evaporation, increase volume, and improve taste (e.g. steamed buns)
Sodium stearoyl lactate (or calcium) works best
2. In candy and chocolate products
It can be used by emulsifiers to control the formation, crystal form and precipitation of solid fat crystals, prevent the return of candy to sand, chocolate frost, prevent the formation of margarine, shortening, chocolate and peanut white shedding and even the formation of coarse crystals in ice cream
Precautions for the use of emulsifiers:
(A) different HLB value emulsifier can prepare different types of emulsion, the selection of suitable emulsifier is the basic guarantee to achieve the best results.
(2) Because the compound emulsifier has a synergistic effect, the compound emulsifier is usually used, but when selecting the emulsifier "pair", it is necessary to consider that the difference between the high value and the low value of HLB should not be greater than 5, otherwise the best stable effect will not be obtained.
(c) Before the emulsifier is added to the food system, it should be fully dispersed or dissolved in water or oil to make a slurry or emulsion.
Fourth, the emulsifier example
Sorbitol anhydride
1) Span series
[Chemical Structure]:
The properties of each sorbitol fatty acid ester vary depending on the composition of fatty acid residues. It is a non-ionic surfactant, and its emulsification ability is better than that of other emulsifiers, but its flavor is poor, so it is generally used with other emulsifiers.
2) Tween series
Span and Tween have two outstanding advantages as emulsifiers: they are significantly resistant to different pHs, and they are more stable when coexisting with high concentrations of electrolytes.
Source: Food R & D and production Finishing, please indicate the source when reprinting.
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