Analysis of the effect of sorbitol incubation on the stability of biochemical properties of peach slices exposed to hot-air dehydration

SALVAÑAL, LARA; GABILONDO, JULIETA; BUDDE, CLAUDIO OLAF; LARA, MARÍA VALERIA

Mendoza

Congreso; LVIII Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology Research; 2022

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Peach fruit is characterized by its fleshy pulp and delicate aroma. It provides vitamins, fiber and antioxidant compounds, among others. Since it is perishable, conservation strategies are needed to expand peach consumption. Traditionally, dehydration with hot air is used to preserve fruit. Osmotic dehydration (OD) before conventional drying is a pre-treatment applied to fresh fruit in order to prevent browning or sugar caramelization during prolonged hot air exposure. The aim of this work was the study of the effect of sorbitol treatment before drying on the nutraceutical and nutritional properties of three peach commercial cultivars. Biochemical properties of OD+D were compared with those of D using slices of Elegant Lady (EL), Dixiland (DX) and Flordaking (FD) peaches. Fruit harvested at commercial maturity were washed, disinfected, cut in slices and was used as fresh material (F). A fraction of F was dried in oven (D) at 58 °C to reach a 10% water content (WC). Another fraction was incubated at 40°C in a solution of sorbitol (47°Brix, OD) during 3 hours under stirring. A water loss of 32% was achieved in the three cultivars. Next, a set of OD slices were dried at 58°C during 4 h (OD+D) until 10% WC. The following parameters were evaluated in F, OD, OD+D and D slices: total phenolics, flavonoids, carotenoids, ascorbic acid, tannins, total protein, glucose, sucrose, sorbitol and antioxidant activity. As expected, in the three cultivars, OD and OD+D slices exhibited an increase in sorbitol –in a dry weight (DW) basis- with respect to F due to sorbitol uptake from the solution. In consequence, dry mass weight of slices incubated in sorbitol was increased between 1.62 and 1.75 times. Thus, this correction factor was applied for analysis and results were expressed in dry weight (DW) basis since samples greatly differ in water content. In all cultivars tested, antioxidant activity measured by DPPH and ABTS methods, total proteins, phenolic compounds and tannins, were greater in OD+D than in D slices. Flavonoids were greater in OD+D than in F in FD; while exhibited the same levels in OD+D and D in DX and EL slices. In DX, carotenoids and ascorbic acid were greater in OD+D than in D. In FD carotenoids were also higher in OD+D than D slices. Regarding sugars, sucrose levels were smaller in OD+D than D in the three cultivars. While glucose was lower in OD+D then in D in DX and EL, it, exhibited the same levels in both types of dehydrated fruit. With respect to the color of the pulp, even though OD+D and D slices were less luminous than F- irrespectively of the genotype- browning was prevented with the OD treatment. Collectively, our results show that OD pretreatment with sorbitol is effective to ameliorate the decay in nutraceutical and nutritional components that usually occurs in D fruit. In addition, the decrease in glucose and sucrose at expenses of the increase in sorbitol makes this treatment suitable for diets restricted in sugars.