Common Quality Issues in Frozen Fruits And Vegetables

Quick frozen fruits and vegetables are a new type of fruit and vegetable processing product that has developed in modern times. They can maintain the color, aroma, taste, and freshness of fruits and vegetables well, and are easy to consume. However, sometimes the quality and taste of frozen fruits and vegetables may deteriorate after processing. What is the reason for this? Let's take a look:
Color change:
① Light colored fruits and vegetables or sliced fruits and vegetables turn red or black in color on the cut surface;
② The green color of green fruits and vegetables gradually fades away and turns into grayish green;
③ Fruit and vegetable products lose their original color or deepen their original color.
The main reason is that fruits and vegetables contain polyphenol oxidase enzymes, which, under the action of oxygen, oxidize phenols into red and black quinone compounds. Chlorophyllase oxidizes and decomposes chlorophyll.
Odor change:
① Fruits and vegetables with irritating odors transmit the odor to milder fruits and vegetables, causing the product to have a skewed taste;
② The cold odor in the cold storage can cause food to spoil;
③ The process of quick freezing fruits and vegetables is not standardized, such as raw materials being frozen or frozen too slowly, insufficient blanching, freezing or temperature fluctuations, repeated freezing causing changes in fruit and vegetable tissue, and odor changes caused by loss of cell fluid;
④ The taste change of fruits and vegetables containing protein and fat after oxidation. The latter two changes in taste are often accompanied by a decrease in taste. Taste change often occurs during the frozen storage stage.
Taste deterioration:
The deterioration of taste mainly refers to the hardening, growth, and fibrosis of the product,
① It occurs during the freezing period, mainly due to the hardening of protein texture after freeze-thaw denaturation, viscosity caused by fat oxidation, water evaporation, and fiber aging caused by oxidation;
② Occurred during the consumption stage, due to improper eating methods, such as slow thawing causing juice loss, resulting in changes in cell structure and fibrosis, there is a feeling of lettuce after cooking.
Nutrient loss:
Good frozen fruit and vegetable products not only have good color, aroma, and flavor, but also should have high nutritional content. However, this point is often overlooked. Although the loss of nutrients often occurs when the color, aroma, and taste of the product change, there are still many processes in processing that can cause the loss of nutrients. For example, washing after cutting can cause the loss of minerals and sugars, while improper heating, freezing, and cooking can cause the loss of vitamins, mainly vitamin C.