The protective effect of Nisin on the nutritional value of food

A key advantage of Nisin in food processing is that it acts not only as a preservative but also indirectly protects food nutritional value by "reducing thermal processing intensity." Its nutrient-protective effect primarily works by inhibiting heat-resistant bacteria and their spores, which reduces the temperature or duration of thermal processing required for sterilization. This minimizes the loss of heat-sensitive nutrients (e.g., vitamins, bioactive peptides), achieving the dual goals of "preservation" and "nutrient retention."

I. Core Mechanism: Replacing "High-Intensity Thermal Processing" with "Low-Intensity Thermal Processing"

In food processing, high-temperature sterilization (e.g., 121°C high-pressure sterilization, 90–95°C pasteurization) is a primary method to extend shelf life. However, it damages nutrients such as vitamins (e.g., vitamin C, B vitamins) and alters protein structures (e.g., denaturation of bioactive peptides). Nisin’s mechanism addresses this by using "biological antibacterial activity" to reduce reliance on "high-temperature sterilization":

1. Targeted Inhibition of Heat-Resistant Pathogens

Nisin is highly effective against common heat-resistant bacteria (e.g., Listeria monocytogenes, Staphylococcus aureus) and their spores (e.g., Clostridium botulinum spores, Bacillus cereus spores) in food. These microorganisms are the main causes of food spoilage and the primary reason for high-intensity thermal processing in traditional methods.

2. Reducing Thermal Processing Parameters

With Nisin added, food no longer requires ultra-high temperatures or prolonged heating to eliminate all microorganisms. To achieve the same shelf-life effect, thermal processing temperatures can be lowered by 5–15°C (e.g., from 121°C to 110°C) or heating duration shortened by 30%–50% (e.g., from 30 minutes to 15 minutes).

3. Minimizing Heat-Induced Nutrient Degradation

The loss rate of heat-sensitive nutrients is positively correlated with thermal processing intensity (temperature × duration). For example:

Vitamin C loses approximately 40% of its content when heated at 100°C for 10 minutes; if the temperature is reduced to 90°C, the loss rate drops to below 20%.

B vitamins (e.g., vitamin B1, folic acid) are prone to decomposition at high temperatures. Reducing heating intensity increases their retention rate by 15%–30%.

II. Specific Nutrient Protection Effects: Differential Improvement for Various Nutrients

By reducing thermal processing intensity, Nisin protects vitamins, proteins, and functional components in food—with particularly notable advantages in heat-sensitive foods.

1. Protection of Vitamins: Reducing Degradation of Heat-Sensitive Vitamins

Water-Soluble Vitamins

Vitamin C and B vitamins (B1, B2, folic acid) are most vulnerable to heat damage. Nisin significantly improves their retention:

In fruit and vegetable juice processing: Traditional pasteurization (95°C for 5 minutes) causes 35%–45% vitamin C loss. With 500 IU/kg Nisin added, the sterilization temperature can be lowered to 85°C for 3 minutes, reducing vitamin C loss to 15%–20% and increasing retention by 20%–25%.

In low-temperature meat products (e.g., ham): Traditional heating (75°C for 20 minutes) leads to 40% vitamin B1 loss. Adding 200 IU/kg Nisin shortens heating time to 10 minutes, reducing B1 loss to 25% while increasing folic acid retention from 55% to 70%.

Fat-Soluble Vitamins

Vitamins A, D, and E have slightly higher heat resistance than water-soluble vitamins but still undergo oxidative degradation under prolonged high temperatures. In dairy products (e.g., cheese), adding Nisin lowers sterilization temperature, increasing vitamin A retention from 60% to 75% and vitamin E retention from 58% to 72%.

2. Protection of Proteins and Amino Acids: Reducing Denaturation and Decomposition

Preventing Excessive Protein Denaturation

High temperatures disrupt protein spatial structures (e.g., denaturation of egg protein, whey protein), affecting digestibility and functional properties:

In liquid milk processing: Traditional ultra-high temperature (UHT) sterilization (135°C for 2 seconds) causes approximately 30% whey protein denaturation. With Nisin added, medium-temperature sterilization (110°C for 2 seconds) reduces denaturation to 15% and increases digestibility from 85% to 92%.

Minimizing Loss of Essential Amino Acids

High temperatures (especially in acidic or alkaline conditions) cause decomposition of essential amino acids such as lysine and methionine:

In plant-based protein beverages (e.g., soy milk): Traditional heating (121°C for 15 minutes) leads to 18% lysine loss. Adding Nisin lowers the temperature to 110°C, reducing lysine loss to 8% and ensuring a more complete amino acid profile.

3. Protection of Functional Components: Maintaining Bioactive Efficacy

Indirect Protection of Probiotics

In probiotic-containing fermented foods (e.g., fermented milk), traditional sterilization kills probiotics. Nisin replaces some heating steps, directly inhibiting harmful bacteria while preserving probiotic activity:

Adding 300 IU/kg Nisin to fermented milk eliminates the need for additional high-temperature sterilization, increasing the survival rate of probiotics (e.g., Bifidobacterium lactis) from 30% to 80%.

Protection of Plant-Derived Bioactive Components

Plant-based bioactive substances (e.g., tea polyphenols, anthocyanins) are prone to heat-induced oxidation. In functional foods (e.g., tea polyphenol beverages), adding Nisin reduces heating intensity, increasing tea polyphenol retention from 50% to 75% and preserving their antioxidant function.

III. Application Scenario Adaptability: Most Effective in Heat-Sensitive Foods

Nisin’s nutrient-protective effect is not universal; it delivers the highest value in heat-sensitive foods where nutrients are easily lost. Key scenarios include:

Liquid foods: Fruit/vegetable juices, dairy products, and plant-based protein beverages. These foods have high water content, fast heat transfer, and easily degraded nutrients. Adding Nisin significantly reduces heating intensity, protecting vitamins and bioactive components.

Low-temperature meat products: Ham, sausages, etc. Traditional heating requires balancing "sterilization" and "texture." Nisin shortens heating time, reduces B vitamin loss, and prevents over-tough meat (caused by excessive protein denaturation).

Fermented foods: Fermented milk, pickles, etc. Nisin inhibits miscellaneous bacterial contamination, reduces secondary heating, and protects probiotics and fermented bioactive peptides (e.g., antimicrobial peptides), enhancing product nutritional value.

IV. Precautions: Key Conditions for Ensuring Nutrient Protection

Nisin’s nutrient-protective effect requires specific conditions to avoid reduced efficacy or other issues:

Controlling Addition Amount: Nisin must be added in compliance with national standards (GB 2760, maximum dosage of 0.2 g/kg, approximately 1000 IU/kg). Excessive addition does not further improve nutrient protection but increases costs.

Matching Appropriate Thermal Processing Parameters: The combination of "Nisin dosage + thermal processing temperature/duration" must be adjusted based on food type and microbial contamination. For example, in high-acidity foods (pH < 4.5), Nisin has stronger antibacterial activity, allowing further reduction of heating intensity.

Avoiding Coexistence with Antagonistic Substances: Fats and proteins in food may bind to Nisin, reducing its antibacterial activity. Formulations (e.g., controlling fat content < 10%) or synergists (e.g., EDTA) should be adjusted to ensure Nisin functions effectively, thereby indirectly guaranteeing nutrient protection.

Nisin’s nutrient-protective effect in food essentially relies on "replacing part of thermal processing with biological antibacterial activity," minimizing degradation of heat-sensitive nutrients. It is particularly effective in retaining vitamins, proteins, and functional components. This dual property of "preservation + nutrient retention" makes it irreplaceable in heat-sensitive food processing and aligns with consumer trends toward "natural preservation and nutrient retention."