Using a red‐fleshed and six varieties of thinned young apple to make juice and their phytochemicals characterization

Abstract

Finding an environmentally friendly way to utilize thinned young apple (TYA) fruits is of great interest in food industry since they were found rich in functional phytochemicals. Making TYA juice is an excellent way but very limited knowledge has been acquired. The juice-making procedures optimization of a red-fleshed and six varieties of TYA fruits were performed with/without steam sterilization before juicing, and the color index, phytochemicals particularly including phenolics and aromas were detailed characterized. Results showed that steaming sterilization of seven TYA were observed conducive to color stability and maintenance, higher sugar contents, comparable acid contents, but lower juice yield and total polyphenol in TYA juices. Moreover, similar polyphenol profiles were detected. Typical 22 aroma compounds were characterized with different profiles and trends in TYA juices. All these findings provide scientific basis for TYA juice making, and demonstrated that TYAs are of great value to develop seasoning juice products. Practical application Fruit thinning is a necessary measure to improve fruit quality in apple production. Thinned young apples can expand the fruit gap through thinning, which is convenient for fruit expansion.The abandoned TYAs in the orchard are posing a risk of environmental pollution, or become host of pathogens to accelerate the spread of fruit diseases. Moreover, discarding the TYAs is a waste of agricultural and food resource since the content of total extractable polyphenols in TYAs is as high as 10 times that in ripe apples. More optimization of processing techniques such as making juice were suggested to improve TYA utilization including the extraction of polyphenols, polysaccharides, and aromas. More food or cosmetics products are expected to be developed based on the TYA juices to improve the commercial value and find an environmentally friendly way to make use of the thinned young fruit.