Effect of different drying method on the chemical and microstructural properties of Loquat slices

Abstract

This study reported the effect of different drying methods, that is, T.D (tray drying) (55°C), V.D (vacuum drying) (55°C), at 500 mm Hg) and F.D. (freeze-drying) (−40°C, 0.006 bar) on microstructural changes, chemical composition changes and sensory parameter (Taste, flavor, color, overall acceptance) of Indian loquat fruit slices. In this research, loquat fruits cut in thin slices (approx. 0.5 cm) and dried by different drying methods. To prevent undesirable browning reaction pre-treatment is carried out by treating 1% potassium meta bisulfite solution for 15 min. Scanning electron microscopy (SEM) was used to analyze the changes in dried fruit structure. Chemical properties of dried products including flavonoids, titratable acidity, Total phenol, ascorbic acid content, β-Carotene, and total sugar were also measured. The result reflected a decrease in chemical properties when compared to fresh loquat fruits. Freeze-dried slices showed significantly higher retention in most of the quality attributes studied in this study. Freeze-dried slices have a porous structure, whereas the tray died and vacuum dried samples showed a compact structure. The sensory analysis resulted that all dried samples accepted by panellists but freeze-dried samples scored a maximum. Practical applications Due to high moisture content (more than 80%) loquat fruit is highly perishable and susceptible to spoilage. Drying techniques preserve this fruit by reducing water activity and extend the shelf life of the fresh fruit making it available throughout the year. Novel drying techniques like freeze-drying help to develop dehydrated and good quality shelf-stable products. The dried slices developed using these techniques may be used by industries for the development of various functional foods, confectionery, and food supplements for children and infants as fruits in dried form also retain high health-promoting nutrition.