Modeling of pre-treatment protocols for frozen pineapple slices

Optimization of pretreatments – blanching and additives was carried out for frozen pineapple slices using response surface methodology (RSM). The effect of pre-treatments viz. blanching medium (10–20° Brix sucrose solution), calcium chloride (1000–2000 ppm) and ascorbic acid (200–400 ppm) was studied on hardness (N), colour (L*), syneresis (%) and sensory attributes (colour, aroma, taste, overall acceptability) of the frozen slices after thawing. A Central Composite Rotatable Design (CCRD) was used with six experiments at the central point. The data obtained were analysed employing multiple regression technique to generate suitable mathematical models. Quadratic models were found to fit well (R2, 96.72–99.99%) in describing the effect of variables on the responses studied. Optimization of the pretreatments was carried out by maximizing the hardness, L* and sensory responses while keeping the syneresis at minimum level. Compromised optimum values for blanching medium, calcium chloride and ascorbic acid levels were found to be 17° Brix, 1493 ppm and 300 ppm; respectively. The experimental and predicted values showed high correlation coefficients. The optimized pretreatment was found to be helpful in maintaining the quality of frozen pineapple slices in terms of texture, colour and syneresis.