Osmo-air dehydration of pineapple (Ananus comosis L.)

Abstract

Studies were carried out to determine the optimum sugar syrup concentration for osmo-air dehydration of pineapple fruits using “Giant Kew” variety and to evaluate quality parameters somatically dehydrated product. Pine apple fruits were washed, peeled, cored and cut in to rectangular pieces and subjected to osmosis for 24 hours in three varying concentrations of sugar syrup (50, 60 and 70 oBrix syrup along with 0.2% citric acid and 700 ppm of potassium metabisulphite) followed by draining the pieces and drying in a drier at 60-65 oC. The dry product was packed in 400 gauge polythene covers and stored at ambient conditions (18-28 ºC, 53-76% RH) and at Low temperature (4 ± 1 ºC, 85-90% RH) up to 6 months. The product was analysed initially and subsequently at 3 months and 6 months. Significantly higher amount of moisture removal from fruits was observed in 70 oBrix syrup closely followed by 60 oBrix syrup. Pineapple fruits subjected to osmosis at 60 oBrix gave maximum dry fruit yield and showed lower moisture, higher ascorbic acid, carotenoids and also higher overall acceptability scores in sensory evaluation initially and also after a storage periods of six months. Storage at low temperature helped in the retention of ascorbic acid, carotenoids, total sugars and sugar acid ratio. Fresh product had lower moisture and reducing sugars. At the end of 6 months storage, the loss of ascorbic acids was to an extent of 37.14% and carotenoids were to an extent of 52.25%. At the end of storage, the product stored at low temperature had better overall acceptability score due to better retention of colour and flavour during storage.