Impact of drying methods and pre-treatments on physical, nutritional and sensory quality of apple slices from high-altitude Spiti valley

Abstract

Apple (Malus domestica Borkh.) cultivation in Spiti Valley has gained commercial significance due to its unique high-altitude agro-climatic conditions, including prolonged chilling, intense solar radiation, and wide diurnal temperature variation, which contribute to superior fruit quality. This study conducted during the 2023–24 season at Krishi Vigyan Kendra (KVK) Tabo evaluated the effectiveness of three drying technologies—traditional sun drying (farmer practice), refrigerator drying, and solar drying with potassium metabisulphite (KMS) pre-treatment—on the physical, nutritional, and sensory quality of apple slices. The results indicated significant differences among the treatments. Solar drying with KMS pre-treatment (T3) was the most effective method, reducing drying time to 2 days, extending shelf life up to 12 months, and producing apple slices with attractive colour, good texture, excellent appearance, and sweet flavour. Traditional sun drying required 5 days and provided moderate quality with 11 months shelf life, while refrigerator drying was the least effective, requiring 6–8 days and resulting in poor sensory quality and shorter shelf life. Sensory evaluation of Spiti Valley apples showed high overall acceptability, with mean scores ranging from 8.2 to 8.5 on a 9-point hedonic scale. The study concludes that solar drying with KMS pre-treatment is a cost-effective and scalable technology for value addition and post-harvest management of apples in high-altitude regions. Future research should focus on optimizing pre-treatment conditions and exploring natural antibrowning agents to further improve quality and marketability.