Effect of citric acid, calcium lactate and low temperature prefreezing treatment on the quality of frozen strawberry

Texture degradation and color fading of frozen strawberries consider to be a serious problem affect their quality. Therefore, in the present study the fresh strawberry immersed in various concentrations of citric acid and calcium lactate alone or in combination for 5 min. and kept at low temperature (5 ºC) for overnight before freezing or frozen directly for controlling these defects. The obtained results declared that pretreatment with citric acid dip obviously enhanced the retention of ascorbic acid and total anthocyanins content and lowered the browning index while Calcium lactate maintained the texture by reducing the drip loss and increasing the firmness after thawing. The precooling treatment did not show any enhancer affect in the quality indices of frozen berries. Compared to the other treatments, the use of 0.4% citric acid – 1% Ca lactate combination dip achieved better quality attributes, including reduction in drip loss and enhancement of firmness, retention of ascorbic acid and anthocyanin content in addition to improving in color attributes.