Techniques for processing of horticultural produce

摘要

Before going for processing and preservation of produce, it is important to understand why and how our food gets spoiled. Spoilage can be detected by smell, taste, touch, or sight and occur are due to a number of reasons - air and oxygen, moisture, light, microbial growth, and temperature. Air consists of 78 per cent nitrogen, 21 per cent oxygen, and 1 per cent mixture of other gases. While oxygen is essential for life, it can have deteriorative effects on fats, food colors, vitamins, flavors, and other food constituents. Oxygen can provide conditions that enhance the growth of microorganisms. Some bacteria require oxygen for growth (aerobes) while others can grow only in the absence of oxygen (anaerobes). Many bacteria can grow under either condition and are called facultative anaerobes. Certain enzymes that are naturally present in food are known as oxidizing enzymes. These enzymes catalyze (speedup) chemical reactions between oxygen and food components, and this leads to food spoilage. Water ormoisture greatly affects the keeping qualities of food. Excessive moisture pickup can result in product spoilage. The moisture in food also functions to allow chemical reactions to occur between components in the product. When temperatures are not properly controlled, food can spoil. For example, for every 10°C rise in temperature within the moderate temperature range where most food is handled, the rate of chemical reaction is approximately doubled. Exposing foods to uncontrolled cold temperatures will also cause physical spoilage.