Cooling of canned fruits and vegetables: During normal pressure sterilization in fruit and vegetable processing, the iron cans can be directly cooled with cold water, and the glass jars need to be cooled in sections; for high-pressure sterilization, the iron cans can be directly cooled, and the glass jars cannot be directly contacted with cold water in the early stage of cooling (section cooling); The cooling water should meet the sanitary requirements of drinking water; be fully cooled (to 38-40℃); wipe the tank immediately after cooling
Utensils for lye peeling: Enamel or stainless steel containers that are resistant to acid and alkali must be used for fruit and vegetable processing, and iron and aluminum products should not be used; maintain the concentration of lye; keep the temperature of lye; % Citric acid neutralized.
Use of preservatives: Fruit and vegetable processing must pay attention to the following issues: certain preservatives must be used in certain conditions and specified foods; the use of preservatives is invalid after food spoilage; some preservatives have peculiar smell, and they cannot affect the original food after being added. Preservatives cannot be used in excess; no one preservative can kill all bacteria, and food spoilage is often not a certain type of bacteria, so it is necessary to study the antibacterial spectrum of preservatives for mixed use.
Pay attention to the temperature and time of blanching: the blanching temperature required for processing fruits and vegetables is not exactly the same. For example, the blanching of spinach at 76.5 ℃ keeps the green color well. If blanched in boiling water, it will cause serious chlorosis; hawthorn should be blanched at 75 Blanch below ℃ to avoid pectin swelling and cracking caused by heat; peas are blanched in boiling water or at a temperature slightly lower than boiling water, depending on the variety and maturity, asparagus is generally blanched at 80℃. Therefore, the selection of blanching temperature and time should be comprehensively considered according to the type, maturity, tenderness, color and other characteristics of specific fruit and vegetable raw materials. Generally, it is treated in boiling water or a temperature slightly lower than the boiling point for 2-10 minutes.
Requirements for blanching liquid: Various fruit and vegetable processing raw materials have different requirements for blanching liquid. For white raw materials, such as edible fungi, asparagus, cauliflower, etc., the pH value of blanching liquid should be adjusted with citric acid to prevent browning. (The pH value of phenolase is 6-7, lower than 6, the activity is obviously weakened, and it can be blanched under the condition of pH=3); green raw materials such as green beans, etc., require adding alkali to the blanching solution to make the pH value It is about 7.5-8.0 (not more than 9) to inhibit chlorophyll demagnesization.
