# Research and Development Status of Prepared Foods in China: A Review
## 7 Existing Deficiencies in the Development of Prepared Foods
### Loss of Nutrition and Flavour of Prepared Foods  
The taste, flavour, colour, and nutrition of prepared foods are key factors in determining whether consumers buy them. However, prepared foods are not easy to preserve [153], and most of them require cold-chain transportation to each sales location. In the process of processing, preservation, distribution, and consumption, prepared foods need to go through the process of bumping, kneading, chilling/freezing, and then thawing and reheating [154]. After these processes, their sensory qualities, such as colour, flavour, taste, and appearance, will be affected [62]. For example, the colour becomes dull from bright, the aroma becomes dull from wealthy, the original flavour disappears, the taste becomes disgusting from palatable, and the appearance becomes shrivelled and collapsed from full and tender. All of these are possible sensory quality problems [155]. Currently, the maintenance of sensory quality is a major challenge for the prepared foods industry, which needs to ensure that the sensory quality of prepared foods is not compromised, while at the same time taking into account the elevated costs. The balance and technical requirements still need to be studied and solved [156].  
Sugars, fats, proteins, vitamins, dietary fibre, and other nutrients [157] are all needed by the human body. They may change during product processing, preservation, and transportation, resulting in their deterioration or loss. For example, [PERSON] et al. found that frying, microwave drying, infrared drying, and hot-air drying can affect the microstructure and quality of protein-enriched instant noodles [158]. At present, the possible changes of nutrients in prepared foods during processing, preservation, and transportation are not concluded and still need to be researched continuously. However, processing methods such as water washing, high-temperature cooking, heat sterilization, and frozen storage cause the loss of vitamins and minerals in prepared foods [33]. In addition, some special prepared foods [159] contain a variety of flavonoids, polyphenols, functional lipids, and other bioactive substances, such as arichrokes, \"DiFara\", deep-sea fish oil, and pre-prepared sea cucumber soup. It provides the pre-prepared foods with some beneficial physiological functions, such as anti-aging, anti-fatigue, sleep aid, and improvement of human immunity [160]. The changing patterns of these active substances during the processing, preservation, and transportation of the products are yet to be explored [161]. How to retain the bioactive ingredients in prepared foods as much as possible and maintain the nutritional quality of prepared foods are the key to broadening the prepared foods market and promoting the development of prepared foods towards high quality.  
At present, there are many ways to reduce the loss of nutrition and flavour of prepared foods. For example, the flavour and nutrient content of prepared foods of fruits and vegetables can be maintained by selecting the best-tasting genotypes to produce, using an integrated crop management system and harvesting at the maturity or ripeness stage to optimize eating quality at the time of consumption, and by using the post-harvest handling procedures that will maintain optimal flavour and nutritional quality of fruits and vegetables between harvest and consumption [162]. Other ways to reduce the loss of nutrition and flavour of prepared foods include using more advanced packaging, such as active packaging, including modified atmospheric, antimicrobial, antioxidant, intelligent packaging, and nanotechnology in food packaging, and using preservation techniques such as ultra-low temperature freezing [163]. Although there are many ways to reduce the loss of nutrition and flavour of prepared foods, their application and optimization still need more research.