Fruit and Vegetable Processing: The Science and Art from Pastoral to Table

fruits and vegetables are an indispensable part of our daily diet, rich in vitamins, minerals, dietary fiber and other nutrients. However, due to their limited shelf life in the fresh state, fruit and vegetable processing has emerged in order to supply the market more widely, meet the needs of different consumers, and reduce seasonal supply constraints. This field covers a variety of technologies from simple cleaning and cutting to complex fermentation and canning. It is an industry that combines scientific principles and traditional techniques.

Fruit and Vegetable Processing

1. Cleaning and classification

this is the initial step in fruit and vegetable processing. The purpose of cleaning is not only to remove the soil and impurities on the surface, but also the possible pesticide residues. For some leafy vegetables, such as spinach and lettuce, a combination of soaking and washing with flowing water is usually used. Fruits, on the other hand, may require special cleaning solutions to ensure the cleanliness of the epidermis. The classification operation is based on the size, shape, maturity and other characteristics of fruits and vegetables, which helps to standardize the operation of subsequent processing steps. For example, when making canned fruit, the uniform size of the fruit can ensure the beauty of the can and the consistency of the quantity.

2. Cutting and peeling

cutting can process fruits and vegetables into different shapes, such as blocks, flakes, filaments, etc., to meet various cooking needs or the convenience of direct consumption. Peel operation is necessary in some processing, such as when making apple sauce, apple peel may affect the taste and need to be removed. Modern cutting and peeling technology includes mechanical cutting and peeling equipment, which can complete the task efficiently and ensure product consistency to a certain extent. However, some small businesses or artisanal workshops may still use hand peeling and cutting to meet specific product needs.

3. Fresh-keeping processing
In order to extend the shelf life of fruits and vegetables, there are a variety of fresh-keeping processing methods. Refrigeration is one of the most common ways, which slows down the growth of microorganisms and the physiological activities of fruits and vegetables by lowering the temperature. Freezing is.

fruits and vegetables are stored at extremely low temperatures, so that the water in them forms ice crystals and prevents the action of microorganisms and enzymes. In addition, modified atmosphere preservation is also an important technology, which inhibits respiration and microbial growth by adjusting the gas composition in the package (such as reducing oxygen content and increasing carbon dioxide content).

4. Drying processing
drying is a method of removing water from fruits and vegetables so that they can be stored for a long time. Common drying methods are natural drying and artificial drying. Natural drying, such as drying raisins, relies on the role of sunlight and wind to dehydrate grapes. Artificial drying includes hot air drying, vacuum drying and so on. The dried fruits and vegetables are not only easy to preserve, but also produce unique flavors in some cases, such as the rich fragrance of dried mushrooms.

5. Canned and Bottled
canned and bottled are processed fruits and vegetables sealed in containers, through high temperature sterilization to achieve the purpose of long-term preservation. In the canning process, fruits and vegetables need to be pre-treated, such as pre-cooked, seasoning and so on. Then put into cans or bottles, add the right amount of soup or syrup, and then seal and sterilization treatment. This processing method allows consumers to enjoy a variety of fruit and vegetable products in different seasons, such as canned yellow peaches and tomato sauce.

6. Fermentation processing
fermentation is the use of microbial metabolism to convert fruits and vegetables into products with special flavor and nutritional value. For example, when making kimchi, lactic acid bacteria convert the sugar in vegetables into lactic acid, which not only increases the sour taste of kimchi, but also inhibits the growth of harmful microorganisms. Wine is made by yeast fermentation of the sugar in the grapes, and the alcohol and other flavor substances produced during the fermentation process give the wine a unique taste and aroma.

scientific principles in fruit and vegetable processing

1. Principles of Microbiology
in fruit and vegetable processing, microbial control is essential. Many microorganisms such as bacteria, molds and yeasts cause spoilage of fruits and vegetables. By means of sterilization, disinfection and fermentation control in the process of processing, the growth of harmful microorganisms can be inhibited, and beneficial microorganisms can be used for fermentation and other beneficial transformations. For example, high-temperature sterilization can destroy the cellular structure of microorganisms, thereby achieving the purpose of extending shelf life.

2. Chemical principles
fruits and vegetables are rich in chemicals, such as sugars, proteins, vitamins, minerals and enzymes. During processing, these chemicals will undergo various reactions. For example, during the heating process, vitaminsC may be destroyed; and in the fermentation process, the catalytic action of enzymes will promote the conversion of sugar into products such as alcohol or lactic acid. Understanding these chemical principles helps to optimize the processing process, maximize the retention of nutrients in fruits and vegetables and create unique flavors.

3. Principles of Physics
physics also play an important role in fruit and vegetable processing. For example, in the drying process, the evaporation of water follows the laws of heat transfer and mass transfer in physics; in canned sterilization, the heat transfer needs to consider the thermal conductivity of the container and the heat distribution of the internal materials to ensure the thoroughness of sterilization.

1. Health and Nutrition Orientation
As consumers become more health-conscious, fruit and vegetable processing increasingly focuses on preserving nutrients. For example, mild processing techniques are used to reduce the loss of vitamins and minerals, and processed products rich in dietary fiber and antioxidants are developed.

2. Convenience and ready-to-eat
the pace of modern life accelerates, consumer demand for ready-to-eat fruit and vegetable products is increasing. This has prompted companies to develop more pre-cut, pre-packaged fruit and vegetable products, such as cut fruit platters and ready-to-eat salads.

3. Sustainable development
in the processing of fruits and vegetables, the impact on the environment has received more attention. This includes reducing energy consumption, reducing packaging waste and using sustainable sources of raw materials.

fruit and vegetable processing is a dynamic and innovative field that closely links agricultural production with consumer demand. Through various processing technologies, we can enjoy a rich variety of fruit and vegetable products, as well as these nutritious foods in different seasons. With the continuous development of science and technology and the continuous changes in consumer demand, the fruit and vegetable processing industry will continue to develop in a healthy, convenient and sustainable direction.