Changes of Physicochemical, Antioxidative and Sensory Properties of Pre-treated Slice Pear Cultivar During Frozen Storage

Pear is a typical fruit of temperate zones with high nutritive values and organoleptic properties. Pears were pre-treated with blanching, osmotic and both blanching and osmotic solution prior to freezing. Two varieties of pear fruit which are Asian pear and Packham pear were analyzed for physicochemical (colour and texture), antioxidative properties (ascorbic acid content, antioxidant activity and total phenolic content) and sensory acceptability. The
pears were subjected to different pre-treatments prior to freezing such as blanching and osmotic solution during storage. The results show that colour attributes of frozen pears were significantly affected by treatment which in contrast to texture properties of frozen pears during storage. Ascorbic acid content of frozen Packham pear was recorded higher (6.38 ± 0.96 mg/100) after treated in osmotic solution compared to frozen Asian pear (4.62 ± 1.15
mg/100) in blanching treatment during storage. The antioxidant activity of frozen Packham pear using DPPH assay exhibited (84.61 ± 0.69 %) contains high scavenging activity on day 1 when treated in blanching treatment while for Asian pear (67.63 ± 2.37 %) in blanching treatment on day 3. Total phenolic content of the frozen pears were found higher in Packham pear (14.77 ± 0.00 mg GAE/g) in control sample whereas Asian pear (3.79 ± 0.00 mg GAE/g) in blanching treatment during storage. Sensory acceptability shows that frozen Asian pear treated in osmotic solution was highly rated among consumers with overall acceptance of 5.80 ± 0.85. Thus, combination of pre-treatment which were osmotic and blanching and freezing helps to retain the quality of frozen pears during period of storage.