As a traditional cooked meat product unique to China, braised and marinated meat products are deeply loved by Chinese people. The traditional processing method of braised and marinated meat products first involves cleaning and trimming the raw meat, followed by pre-cooking. A spice bag composed of various spices is added to the braising liquid for braising.
At present, most of the braised and marinated meat products in China are still processed in the traditional way, which has disadvantages such as low yield and unstable quality. Among them, the short shelf life of traditional Chinese braised and marinated meat products has become a major problem, which restricts their long-distance transportation and industrial production, seriously hindering the development of traditional Chinese braised and marinated meat products.
At present, the preservation and freshness of braised and marinated meat products are mainly achieved by killing microorganisms or inhibiting the growth and reproduction of related microorganisms. Common sterilization techniques at home and abroad include thermal sterilization, microwave sterilization, and irradiation sterilization. Preservatives mainly include chemical preservatives, natural preservatives, and compound preservatives.
At present, most of the braised and marinated meat products in China are still processed in the traditional way, which has disadvantages such as low yield and unstable quality. Among them, the short shelf life of traditional Chinese braised and marinated meat products has become a major problem, which restricts their long-distance transportation and industrial production, seriously hindering the development of traditional Chinese braised and marinated meat products.
At present, the preservation and freshness of braised and marinated meat products are mainly achieved by killing microorganisms or inhibiting the growth and reproduction of related microorganisms. Common sterilization techniques at home and abroad include thermal sterilization, microwave sterilization, and irradiation sterilization. Preservatives mainly include chemical preservatives, natural preservatives, and compound preservatives.
I. Sterilization Technology
1. Thermal sterilization is a widely used sterilization method at present. Although it is a common method, there are still some problems in effectively and scientifically applying it in actual production. Thermal sterilization can be divided into low-temperature thermal sterilization and high-temperature thermal sterilization. The temperature for low-temperature sterilization is below 100℃, and for high-temperature sterilization, it is above 100℃. At low temperatures (less than 70℃), most of the nutrients in meat products can be preserved, and most pathogenic bacteria can be killed, but only a few spore-forming bacteria remain. However, when the temperature reaches 120℃, all microorganisms in meat products can be killed in a very short time. Kang Huai-bin used low-temperature sterilization technology (85-90℃) to treat roast chicken products for 30 minutes and achieved good sterilization results. The product had uniform color, complete shape, and good taste, but its shelf life was relatively short. Zhang Pei-qi used high-temperature sterilization technology (121℃) to treat braised pig's feet for 20 minutes, achieving good sterilization results and extending the shelf life, but it affected the quality of the product. Therefore, it can be seen that different products have different temperature tolerances, and different sterilization temperatures should be selected. Products with strong tolerance should be sterilized at relatively higher temperatures, while those with weak tolerance should be sterilized at relatively lower temperatures.
2. Microwave sterilization refers to electromagnetic waves with wavelengths ranging from 1m to 1mm. This sterilization method uses the heat generated by the high-energy molecular friction caused by the vibration of electromagnetic waves to sterilize. It has the characteristics of high efficiency, low energy consumption, and wide application range. Microwave sterilization can generally be carried out in two ways: sterilization before packaging and sterilization after packaging. In traditional braised and marinated meat products, sterilization after packaging is often used, which can avoid secondary contamination. However, this method requires strict quality control at each stage. Sun Cheng-feng applied microwave heating sterilization technology to the production of braised beef, and Rui Han-ming applied it to the industrial production of white-cut chicken, both achieving good results and effectively extending the shelf life.
3. Irradiation sterilization uses high-energy rays such as X-rays, gamma rays, and high-energy electron beams with extremely short wavelengths to irradiate meat products to achieve sterilization. This method can remove most microorganisms and pathogenic bacteria without significantly affecting the nutrition and flavor of meat products, and it can also significantly improve the hygiene quality of meat products. Xu Yi-qing used irradiation sterilization technology to treat soft-packaged braised beef and found that an irradiation dose of 8.02kGy or above could ensure a shelf life of more than 28 days for soft-packaged braised beef, and the sensory quality of the product was not damaged. Although irradiation sterilization has good effects, it has disadvantages such as high equipment requirements, large one-time investment, and the need for centralized processing, which brings difficulties to the sterilization of traditional braised and marinated meat products.
II. Preservatives
The addition of preservatives is a commonly used method for preserving meat products in China. According to their sources, preservatives can be classified into chemical, natural and compound types.
1. Chemical preservatives are convenient to use and have good preservation effects, making them the most commonly used food preservation method at present. Common chemical preservatives in meat products include sodium nitrite, sulfites, EDTA, benzoic acid, sorbic acid, potassium sorbate, ascorbic acid, and phosphate salts, etc. Potassium sorbate is widely used in meat products. El-Aal et al. found that when potassium sorbate and ascorbic acid were used in combination on beef and stored for 10 days, the total number of anaerobic bacteria and psychrophilic bacteria was lower than that of the group treated with ascorbic acid alone. However, the use of chemical preservatives in China is often not standardized, leading to frequent incidents of food poisoning, teratogenicity, and carcinogenicity.
2. Natural preservatives
Common natural preservatives include nisin, lysozyme, chitosan, and natamycin, etc. In addition, in traditional Chinese meat product processing, natural spices such as garlic, Sichuan pepper, cinnamon, cloves, and thyme are often used. These spices contain rich preservative substances such as allicin, polyphenols, flavonoids, and functional fatty acids, and are thus also used as food preservatives. These spices have certain antibacterial effects.
Natural preservatives are substances extracted from animals, plants, and microorganisms or their metabolic products that have preservative effects. They are relatively safe and well accepted by consumers. Natural preservatives have a wide range of applications, good thermal stability and safety, and are a major category of preservatives currently under extensive research.
Natural preservatives can not only effectively extend the shelf life of food, but also are safe to consume and have little or no impact on the taste, color, and flavor of food. Among natural preservatives, microbial source preservatives are increasingly attracting the attention of researchers due to their strong antibacterial properties, good water solubility, good thermal stability, and safety and non-toxicity.
3. Compound preservatives
Compound preservatives are a mixture of natural and chemical preservatives in a certain ratio. This type of preservative can be combined and used according to the type of meat product to be sterilized and the types of microorganisms, taking advantage of their strengths and avoiding their weaknesses to achieve comprehensive sterilization effects. Cai Shimeng used compound preservatives to extend the shelf life of braised beef; Xu Shiming used compound preservatives to extend the shelf life of roast chicken.
III. Packaging Technology
Appropriate packaging materials should be used to wrap food to maintain its value and original state during transportation, storage and sale. The premise of preservation is that the initial bacterial count of the sample is low; otherwise, the effect of extending the shelf life cannot be achieved. Common packaging technologies include vacuum packaging, modified atmosphere packaging, and edible coating technology, etc.
1. Vacuum packaging technology
It mainly achieves the preservation of meat products through four aspects: reducing the moisture loss of meat products, slowing down the oxidation rate of fat in meat, controlling the growth and reproduction of microorganisms, and preventing secondary pollution. When the initial total bacterial count is low, the preservation effect of vacuum packaging is obvious.
2. Modified atmosphere packaging
Modified atmosphere packaging is a technology that seals food in an altered gas environment to protect the color of meat, inhibit the growth of microorganisms and delay enzymatic reactions, thereby extending the shelf life of the product. The gases commonly used in modified atmosphere packaging are carbon dioxide, oxygen and nitrogen or their combinations, and each gas has a different effect on food preservation. Oxygen mainly helps the coloration of fresh meat, carbon dioxide mainly has an inhibitory effect on bacteria, and nitrogen is often used as a filling gas. Studies have shown that low-oxygen packaging can effectively inhibit the growth of spoilage bacteria in stored braised meat products.
3. Edible coating
It is a protective film formed by the interaction of edible substances. There are many materials that can be used as edible coatings, such as alginates, pectin, starch, gelatin, natural waxes, and surfactants. Lan Fengying et al. treated braised beef with an edible chitosan coating agent. After dissolving chitosan in acetic acid solution, a chitosan coating solution was prepared. The chitosan coating solution could extend the shelf life of braised beef by about 6 days, and the coating treatment had no adverse effect on the sensory quality of the product. In actual production, we have found that heating sterilization, microwave sterilization, irradiation sterilization, chemical preservatives, natural preservatives, and compound preservatives all have certain effects on the growth and reproduction of microorganisms in braised meat products. However, a single technology may have certain deficiencies and shortcomings in a certain aspect. Therefore, in order to extend the shelf life of braised meat products, heating sterilization methods should be combined with preservatives to inhibit the growth and reproduction of microorganisms in braised meat products from different aspects and thus extend the shelf life. Therefore, the combined use of multiple methods will become the trend of the development of preservation technology for braised meat products in China.
