Natural preservatives are derived from natural resources and have safe, green and efficient preservative properties. Therefore, they are more widely used in food than chemical synthetic preservatives, and the importance of natural preservatives is increasing. At present, research on the application of natural preservatives in food has been carried out, and new natural preservatives are constantly being explored.
Current status of research on natural food preservatives
Natural preservatives refer to a class of functional substances with antibacterial and preservative effects that are separated and extracted from plants, animals and microorganisms or their metabolites. They are safer than chemical preservatives.
In the food industry, preservatives are often added to reduce losses, improve quality and extend shelf life. Currently, the commonly used preservatives are mainly natural preservatives and chemical preservatives. Chemical preservatives mainly include sorbates, nitrites and benzoates. Although these preservatives have been used for many years, people's concerns about the safety of these preservatives have never decreased. Most chemical preservatives still have some potential hazards to human health.
Mamur et al. found that sodium sorbate is genotoxic to human peripheral blood lymphocytes; researchers also found that when these preservatives are used together, they will have adverse effects on human health. Binstok et al. reported that due to the risk of forming mutagenic compounds, the combined use of sorbates and nitrites in meat products should be minimized.
The use of chemical preservatives in food preservation may cause certain harm to human health and the environment, while natural preservatives have the advantages of low toxins, no odor, safety and high efficiency. They are not only harmless to the human body, but also have certain nutritional value.
Sources and applications of natural preservatives
Natural food preservatives have the advantages of strong antibacterial properties, high safety, and good thermal stability. According to their sources, they can be divided into plant preservatives, animal preservatives, and microbial preservatives. Due to the different sources of various natural preservatives, their composition and structural characteristics are different, and their applications in food are also different.
1. Plant preservatives
Plant preservatives are mostly derived from plant extracts, such as certain natural herbs and spices, and essential oils. Due to their unique flavor and antibacterial and preservative effects, plant extracts and essential oils have long been used as food preservatives, seasonings, and medical preparations.
Plant extract
Plant extracts are usually obtained from the roots, stems, leaves, flowers, fruits, bark, and other parts of plants. Some extracts have a strong taste and can cause sensory discomfort at high concentrations, so their concentrations should be limited. The qualitative and quantitative changes in the content of bioactive phytochemicals in plant extracts lead to changes in their effectiveness. These phytochemicals also affect the microbial content, taste, and flavor of food. Due to their specific phytochemical composition, plant extracts have certain antibacterial activity. Plant extracts obtained from herbs, spices, vegetables, and fruits have antibacterial effects on bacteria, yeast, and mold. Studies have shown that plant extracts are very effective in controlling the growth of foodborne pathogens.
Plant extracts are rich in natural antioxidants, and antioxidants play an important role in food. Antioxidants are additives that can delay or prevent food from becoming rancid due to oxidation, and can extend the shelf life of food. Most plant-based antioxidants show protective effects similar to butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), and a variety of vegetables and fruits can be considered as important sources of natural antioxidants for strengthening and stabilizing food. Researchers have studied the antioxidant effects of plant extracts in food and found that tomato and garlic extracts can delay lipid oxidation during the freezing of fish and pickling of anchovies.
Essential oils
Essential oils are aromatic and volatile liquids obtained from natural herbs and spices. They contain a large amount of secondary metabolites and have the effect of delaying or inhibiting the growth of bacteria, yeast and mold. Essential oils, as part of spices or herbs, have been used in the food, medicine, perfume and cosmetics industries for centuries.
In the food industry, essential oils are mainly used as flavoring agents. The chemical composition of plant essential oils is not only related to the growth environment of the plant, but also to many factors such as the type of plant, the collection season of plant materials, the collection part, and even the extraction method of essential oils. The strongest antibacterial activity in herbal essential oils is during or after flowering. Some antibacterial compounds in essential oils are naturally present in plants, while others are produced by plants when they face microbial attacks or are damaged. Since most essential oils have mature extraction processes, strong antibacterial effects, and are non-toxic and harmless, they stand out as a natural antibacterial agent in food preservation.