Study On The Textural Changes And Pectin Degradation Of Tarocco Blood Orange And Lemon During Storage

The taste and storage time is one of the main indicators to measure the quality of fruit,which directly affects its acceptability and supply to the consumer market and its economic benefits.During postharvest storage,the tissue structure and cell wall properties of the fruit are closely related to pectin,which has special physical,chemical,and biological characteristics.The pectin degradation in the cell walls and middle lamella greatly affects the texture of the fruit.Therefore,it is of great significance to study the influence of the chemical changes of the pectin in the fruit peel on the physical and chemical properties of the fruit.Then establish the relationship between the changes in the chemical structure,matrix,and molecular weight of pectin and the changes in texture and taste of the fruit for the improvement in fruit preservation methods.Citrus fruit is rich in pectin and is one of the main sources of commercial pectin.Studying the relationship between pectin changes and degradation and texture changes during postharvest storage of Tarocco blood orange and lemon fruits is an important application foundation study.In-situ optical microscope analysis,rapid assay,gravitational method,and carbazole method were used to study the spatial distribution,degree of esterification,degree of methylation,pectin content,and galacturonic acid content of pectin in the peel at different periods after harvest.The degradation and structural changes of pectin were systematically analyzed by molecular weight measurement and infrared measurement.At the same time,the changes of physical and chemical indicators such as post-harvest fruit weight loss,moisture content,anthocyanin content,citrus color index,total acid,and reducing ascorbic acid were evaluated.The texture analyzer was used to characterize the texture changes of the fruits.The effects of the combined calcium chloride and 1-methylcyclopropene treatment on fruit texture changes and pectin degradation were investigated.The results show that as storage time prolonged,the degree of pectin degradation gradually deepened due to the dissolution,depolymerization,and de-esterification of pectin,which ultimately led to the decrease of the mechanical properties of the fruit,the increase of WL,the decrease of water content and the decrease of fruit volume.After 63 days of storage of Tarocco blood orange,the molecular weight of pectin decreased from568.05 k Da to 362.55 k Da,and the content of pectin decreased by 42.1%.The combined application of calcium chloride and 1-methylcyclopropene effectively inhibited the degradation of lemon pectin.The pectin content of fruits stored for 42 days under the preservative treatment was 22.39% which was higher than that of the control.For the treated fruits,the rate of weight loss,loss of water,total acidity,and other parameters were extended by at least 14 d compared to the control stored for 28 d.The research results show that the control treatment for the degradation of pectin can reduce the texture of the fruit,deaccelerate the color change of the peel and maintain a better appearance of the fruits.The effect of pectin degradation on the texture and physical and chemical properties of Tarocco blood oranges and lemons provides a theoretical basis for the storage optimization,quality control,and shelf-life extension of post-harvest fruits.