Influence of temperature and blending time on quality of minimally processed puree from four melon types

Demand for natural and fresh fruit juice with high quality in terms of nutritional value, physiochemical and sensory characteristics compared to pasteurized products has considerably increased. The objective of this study was to determine the optimal blending conditions to obtain high quality minimally processed melon puree. A Central Composite Design was developed, and ten temperature/time combinations, ranging from 0 to 21C, and from 5 to 140 s were tested. Fresh purees from 4 melon types ('Cantaloupe', 'Galia', 'Amarillo', and 'Piel de Sapo') stored at 5C for 6 days were compared. For all genotypes, physical (color, consistency), chemical (Vitamin C, total phenols, antioxidant capacity, pH, titratable acidity, total soluble solids) and sensorial attributes (browning, smoothness, odor, freshness, sweetness and acidity) were monitored before processing, and at the end of cold storage. Time of blending influenced puree smoothness; fruits blended for about 80 s reached their optimal homogeneity. For 'Cantaloupe' and 'Piel de Sapo' puree, time of blending significantly impacted on Vitamin C (higher reduction for blending longer than 60 s). Moreover in 'Cantaloupe' puree the increase of process temperature reduced the total phenolic content indicating a possible oxidation. 'Amarillo' melon puree was the most sensitive to color changes; time of treatment significantly affected a∗, b∗, and Chroma attributes, inducing a high proportion of browning during storage. On the other hand, processing conditions did not affect the quality parameters of 'Galia' puree with the exception of L∗value which decreased with the increase of the time of processing. Although quality attributes limiting melon puree's shelf-life depended more on the melon type, blending time was the most critical factor affecting nutritional and sensorial losses. A general recommendation for all melon types is to blend melons at low temperatures for not longer than 80 s.