A) Preservation characteristics of new atmosphere food:
Sterilization is the primary link in preserving food. In the processing process of new atmosphere food, when pre-treating food raw materials, seasoning and cooking are combined, and sterilization treatment is carried out at the same time. Sterilization treatment and multi-stage warming mild sterilization cooperate with each other. Sterilization under low F value (generally below 4) conditions can meet commercial aseptic requirements, thereby retaining the color, aroma and taste of food to the greatest extent. Table 2 lists the F values of various new atmosphere foods when sterilized and the bacterial inspection results after 14 days of insulation at 37°C.
Oxygen isolation is an important condition for preserving food. New atmosphere food uses transparent packaging materials with high barrier properties. After conditioning and sterilization, it is stored at room temperature and away from light for 120 days, and the color, texture and flavor of the food are checked. The results are shown in Table 3. We can set a shelf life more reasonably. According to the Food Sanitation Law of Japan, after sterilization, the number of bacteria in each gram of food should not exceed 300 after being kept at 37℃ for 48 hours. Since fresh atmosphere-conditioned food has reached the commercial sterile state, it can be stored at room temperature for one year from the perspective of sterilization alone. However, the shelf life is also limited by the oxygen permeability of the packaging material, the gas replacement rate during packaging, and the change in the moisture content of the food. If the packaging material is heated at 120℃ for 20 minutes, the oxygen permeability is not higher than 2-3 cc/24 hr.·m2, the nitrogen purity used is above 99.9%, and the gas replacement rate reaches above 95%, the tasting period can reach six months.
B) Taste of fresh atmosphere-conditioned food:
Taste is an important factor in determining food quality. The taste depends not only on the quality of the food raw materials, but more importantly on the processing technology and sterilization conditions. The taste of food can be evaluated by subjective or objective methods. The former is evaluated by the softness and hardness, smoothness, tongue and teeth touch and chewing feeling of the food, which is easily limited by human factors and experience. The latter is objectively evaluated by mechanical methods. The taste difference between fresh gas-conditioned food and vacuum-packed, high-temperature and high-pressure sterilized food can be measured and analyzed by rheometer.
2026
