Characterization of juice extraction methods utilizing fresh mayhaw (Crataegus opaca Hook.) fruit.

摘要

Six juice extraction methods for mayhaw cv. Texas Star were evaluated for percentage juice yield, pH, degrees Brix (soluble solids), titratable acidity (TA), sugar/acid ratio, sugar and organic acid contents, and colour of extracted juices from fresh fruits. Methods studied were steam extraction using whole fruits with added pulp juice (SEP) or without added pulp juice (SE), cold-press extraction using whole fruits (CPE) or finely ground fruits (CPEG), hot-press extraction using finely macerated fruit pulp (HPEG), and hot-press extraction in combination with a pectolytic enzyme pretreatment (ENZ). Juice quality was determined by HPLC analysis of sugar and individual organic acids. Juice quality and extraction efficacy were significantly (P <=0.05) affected by extraction. Steam extraction using whole fruits with added pulp juice produced the highest yield (70.3%). Fructose and glucose were predominant sugars and malic acid was the predominant acid in all extracted juices. SEP produced juice with lowest amount of total sugars. TA and pH of all extracted juices were significantly (P <=0.05) affected by the extraction methods. The lowest TA value was for SE at 0.51% and highest for HPEG at 1.28%.The lowest pH were for CPE at 2.97 and highest pH at 1.13 for SE. L* values (lightness) of fresh juices were significantly (P <=0.05) affected by extraction method. Cold extraction methods yielded juices with more intense redness and yellowness (a* = 5.2, b* = 1.92, chroma = 5.5, hue angle = 19.8) than did steam extraction.