1 Department of Chemical and Materials Engineering, University of Auckland, Auckland, New Zealand.
2 Department of Food and Process Engineering, Universiti Putra Malaysia, Selangor, Malaysia.
Food Sci Technol Int. 2017 Jun;23(4):293-309. doi: 10.1177/1082013216685485. Epub 2016 Dec 19.
Strawberry puree was processed for 15 min using thermal (65 ℃), high-pressure processing (600 MPa, 48 ℃), and ultrasound (24 kHz, 1.3 W/g, 33 ℃). These conditions were selected based on similar polyphenoloxidase inactivation (11%-18%). The specific energies required for the above-mentioned thermal, high-pressure processing, and power ultrasound processes were 240, 291, and 1233 kJ/kg, respectively. Then, the processed strawberry was stored at 3 ℃ and room temperature for 30 days. The constant pH (3.38±0.03) and soluble solids content (9.03 ± 0.25°Brix) during storage indicated a microbiological stability. Polyphenoloxidase did not reactivate during storage. The high-pressure processing and ultrasound treatments retained the antioxidant activity (70%-74%) better than the thermal process (60%), and high-pressure processing was the best treatment after 30 days of ambient storage to preserve antioxidant activity. Puree treated with ultrasound presented more color retention after processing and after ambient storage than the other preservation methods. For the three treatments, the changes of antioxidant activity and total color difference during storage were described by the fractional conversion model with rate constants k ranging between 0.03-0.09 and 0.06-0.22 day , respectively. In resume, high-pressure processing and thermal processes required much less energy than ultrasound for the same polyphenoloxidase inactivation in strawberry. While high-pressure processing retained better the antioxidant activity of the strawberry puree during storage, the ultrasound treatment was better in terms of color retention.
草莓泥经过 15 分钟的热处理（65°C）、高静压处理（600MPa、48°C）和超声处理（24kHz、1.3W/g、33°C）。这些条件是基于类似的多酚氧化酶失活（11%-18%）选择的。上述热、高静压和功率超声处理所需的比能分别为 240、291 和 1233kJ/kg。然后，将加工后的草莓在 3°C 和室温下储存 30 天。储存过程中恒定的 pH 值（3.38±0.03）和可溶性固形物含量（9.03±0.25°Brix）表明微生物稳定性。多酚氧化酶在储存过程中没有重新激活。与热处理（60%）相比，高静压处理和超声处理更好地保留了抗氧化活性（70%-74%），在室温下储存 30 天后，高静压处理是保持抗氧化活性的最佳处理方法。与其他保鲜方法相比，经超声处理的果泥在加工后和室温储存后颜色保持更好。对于三种处理方法，抗氧化活性和总色差的变化在储存过程中均采用分数转化模型描述，速率常数 k 分别在 0.03-0.09 和 0.06-0.22 天之间。总之，在相同的草莓多酚氧化酶失活程度下，高静压处理和热处理所需的能量比超声处理少得多。虽然高静压处理在储存过程中更好地保持了草莓泥的抗氧化活性，但超声处理在颜色保持方面更好。
