Comprehensive Utilization of Thinned Unripe Fruits from Horticultural Crops

Abstract

Fruit thinning is a cultivation technique that is widely applied in horticulture in order to obtain high-quality horticultural crops. This practice results in the discarding of a large number of thinned unripe fruits in orchards each year, which produces a great waste of agricultural resources and causes soil pollution that may be an important reservoir for pest and plant diseases. Current studies showed that bioactive compounds such as polyphenols, organic acids, monosaccharides and starches are present in unripe fruits. Therefore, we reviewed the bioactive components obtained from thinned unripe fruits, their revalorization for the food industry, their beneficial effects for human health and the methods for obtaining these components. We also performed a calculation of the costs and benefits of obtaining these bioactive compounds, and we proposed future research directions. This review provides a reference for the effective utilization and industrial development of thinned unripe fruits obtained from horticultural crops. Furthermore, revalorizing the waste from this cultural practice may increase the economic benefits and relieve the environmental stress.

Lab Scale Extracted Conditions of Polyphenols from Thinned Peach Fruit Have Antioxidant, Hypoglycemic, and Hypolipidemic Properties

“…Although polyphenols in thinned apples, pears, and grapes have attracted interest, relatively few investigations have focused on TPPs [ 2 ]. These studies tend to emphasize polyphenol composition and function, while polyphenol extraction and purification have not received the same attention [ 8 , 9 ].…”

“…Polyphenols have diverse biological activities, including antioxidant, hypoglycemic, and hypolipidemic effects [ 2 ]. In order to systematically explore and evaluate the antioxidant capacity of TPPs, it is advantageous to test multiple indicators simultaneously [ 34 ].…”

“…In recent years, agricultural by-products have attracted increasing attention because of their potential value as raw materials [ 1 ]. Horticultural crops with high fruit setting rates, such as apples, pears, grapes, and peaches, are often thinned to ensure fruit yield and quality [ 2 ]. During thinning, large quantities of immature fruits are routinely discarded; the yield of thinned fruits per acre is 30–50 kg/acre for thinned apples, and 100 kg/acre for thinned pears and thinned peaches [ 2 ].…”

“…Horticultural crops with high fruit setting rates, such as apples, pears, grapes, and peaches, are often thinned to ensure fruit yield and quality [ 2 ]. During thinning, large quantities of immature fruits are routinely discarded; the yield of thinned fruits per acre is 30–50 kg/acre for thinned apples, and 100 kg/acre for thinned pears and thinned peaches [ 2 ]. Unfortunately, thinned fruit is typically regarded as a nearly worthless by-product rather than as a potentially valuable raw material.…”

“…Thinned fruit is rich in polyphenols that possess antioxidant, antibacterial, and anticancer activities [ 2 , 4 ]. Polyphenol concentrations in thinned apple are approximately 10 times higher than in mature apples, and the antioxidant levels decrease gradually as the fruit reaches maturity [ 5 ].…”