Quality characterization of freeze-dried tropical strawberries pretreated through osmotic dehydration

The development of dried fruit products is not widely practiced in Indonesia. Strawberry ( Fragaria x ananassa ) is a fresh fruit that can produce dried products, although thermal drying is associated with bioactive substance loss and discoloration. This shows the need for technologies such as nonthermal freeze-drying to protect the color, flavor, nutrition, appearance, and uniformity of dried products during processing and storage. Therefore, this research aimed to determine the physical, microstructural, aroma, chemical, and microbiological of pretreated freeze-dried strawberries (FDSs) with osmotic dehydration (OD). Fully mature strawberries were obtained from Inggit Strawberry Orchard, Sawangan, Magelang, Central Java, Indonesia. FDSs were processed with and without OD pretreatment and dried using a freeze-dryer machine. Compared to fresh strawberries, both freeze-dried products showed increased L∗, a∗, total acid, total phenolic content, and antioxidant activity, with decreased b∗, water content, and water activity. This showed that FDSs with OD pretreatment offered several advantages compared to those without pretreatment. Pretreated OD-FDSs had lower water content (10.84 %), a harder texture (4.8 N), higher phenolic content (8.11 mg GAE/g), and lower total acidity (71 mg/g). Consequently, panelists preferred pretreated OD-FDSs for its crispier and more delicate texture. OD-FDSs delivered a better overall flavor with reduced residual sourness and acidity, despite similar preferences for shape, color, and aroma. Pretreated OD-FDSs preserved total aerobic bacteria and water activity levels according to Indonesian National Standards (SNI) 3710:2018, which enhanced shelf life. The results suggested that the method effectively enhanced the selling value of strawberries, particularly those with high acidity, by extending shelf life, preserving shape, color, aroma, as well as improving taste and texture. • Freeze-dried strawberries using tropical strawberries production is product innovation for tropical consumer. • Freeze-dried strawberries need quality characterization information. • Osmotic dehydration treatment is important during freeze-dried strawberries processing. • Beneficial of osmotic dehydration can be maximized preservation, nutritional's products and better sensory evaluation. • Freeze-dried strawberries could be produced for supporting human health with potentially on larger scale.