In order to obtain the best results, food preservation is increasingly being carried out with a combined system (hurdle technology), using the synergistic action of several factors that inhibit the growth of microorganisms that cause food spoilage.
The most common “hurdles” (obstacles to microbial growth) are:
In this article, we will turn our attention to the use of bacteriostatic. As substances that inhibit the growth and reproduction of bacteria, they ensure the safety and extend the shelf life of food products.
A group of compounds formed by acetic fermentation. They are mainly used as:
In the meat industry, mixtures of acetates and lactates are often used. Both lactates and acetates show very good growth inhibitory properties against L. monocytogenes, Clostridium. They do not require high dosage (0.2 -1.5% in relation to meat used in the product). They do not negatively influence sensory properties of products (taste, smell, colour, texture). Using potassium salts allows to decrease the salt content in products (according to nutritionists, we consume far too much of it, which is harmful to our health).
The results of research clearly show that the best results are obtained with mixtures of lactates and acetates. They effectively inhibit the growth of microorganisms, including pathogenic ones, e.g. L. monocytogenes. Products prepared with lactate-acetate combinations stored at 4 °C for 90 days retain their sensory parameters such as taste, texture and colour. Moreover, in comparison with control samples (without the addition of bacteriostatic), lower growth of microorganisms and inhibition of L. monocytogenes are noted. The obtained results show that thanks to the use of compounds inhibiting the growth of microorganisms in the products is possible to extend the shelf life by 50-60%.
Perhaps in the near future we will also learn the results of research conducted by research centres on the effect of bacteriostats on the safety of meat products packaged in MAP (sausages, wieners, cooked ham).
A group of compounds found in fruits, vegetables, cereal and legume seeds, nuts, coffee, tea, and cocoa, which:
In recent years, interest in phenolic compounds has grown due to their pro-health, antioxidant, and antimicrobial properties. Since polyphenolic compounds are found in plant products, many studies have analysed the antimicrobial properties of plant extracts containing phenolic acids.
Scientists analysed the antimicrobial effects of phenolic acids, contained in extracts of blueberry leaves, different species of white and red wines, and salts of phenolic acids, and confirmed their antimicrobial activity. Although they did not act equally on all strains of bacteria, Gram-positive bacteria were more sensitive to the phenolic acids. The study confirmed that phenolic compounds effectively inhibit the growth of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica. They also have an antifungal effect.
Polyphenolic acids also have a strong antioxidant effect. Chlorogenic acid occurring in fruits: apples, strawberries, pineapples added in a concentration of 50 mg/l to fruit stored at 25 ° C has the ability to inhibit the formation of superoxide radical and hydrogen peroxide. Moreover, in fruits treated with chlorogenic acid, an increase in the activity of enzymes responsible for the neutralization of free radicals was noted.
Long-standing research confirming the antioxidant capacity of rosemary extract resulted in its qualification as an antioxidant food additive with E 392 code under Directive 95/2/EC. Besides rosemary extracts, water extracts of dill and thyme also have high antioxidant activity against meat lipids when added to chicken or turkey meat stored frozen for 6 months.
Extending the shelf life of meat and fish products is also possible by using bacterial cultures. These are isolated and specially grown strains of bacteria, which through competitive displacement and production of lactic acid and bacteriocins inhibit the growth of rotting and pathogenic bacteria.
Interest in protective cultures has been growing recently due to increased consumer awareness of the impact of food ingredients on their health. Although the use of only protective cultures may not be sufficient to fully ensure microbiological safety, they are increasingly used in meat processing as part of hurdle technology, as one of many elements designed to ensure product safety. On the shelves we can find, among others, minced meat or sliced raw bacon, which, in addition to meat, salt and other spices, contains live cultures of lactic fermentation bacteria. Analysing the needs of the market, we can conclude that this trend is bound to grow.