Pear puree was acidified with citric acid and was subjected to thermal (TP) and high pressure-thermal processing (HPTP). Citric acid inhibited peroxidase (POD) and polyphenol oxidase (PPO) and preserved the color of pear puree. The addition of citric acid (2%, w/w) increased total phenolic content (TPC) and oxygen radical absorbance capacity (ORAC) of pear puree by ~ 50%. POD was more sensitive than PPO to thermal and HPT inactivation. Citric acid enhanced thermal and HPT inactivation and complete inactivation of POD was observed after TP (90 °C, 7 min) and HPTP (600 MPa, 90 °C, 5 min) in acidified samples, while a maximum 60% inactivation of PPO was observed under these conditions. TP resulted in a slightly better color retention of acidified samples than HPTP under conditions of equivalent enzyme inactivation, whereas TPC and ORAC remained stable irrespective of the process.

Industrial relevance

This study investigated the effect of thermal and high pressure thermal processing with and without citric acid on the activity of oxidative enzymes and related quality attributes of pear puree. Citric acid inhibited enzymatic browning, protected polyphenolic antioxidants against oxidative degradation and resulted in 50% increase in antioxidant capacity when it was added at 2% (w/w). Acidified pear puree can possibly be used as an ingredient in products such as yoghurts, jams and baby food after either thermal or high pressure thermal processing due to its reduced oxidative enzyme activity, low pH, high antioxidant capacity and excellent color retention.

中文翻译：

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柠檬酸和高压热处理对梨泥酶活性及相关品质属性的影响

梨果泥用柠檬酸酸化，然后进行热处理（TP）和高压热处理（HPTP）。柠檬酸抑制过氧化物酶（POD）和多酚氧化酶（PPO），并保留梨泥的颜色。添加柠檬酸（2％，w / w）可使梨泥的总酚含量（TPC）和氧自由基吸收能力（ORAC）提高约50％。POD比PPO对热和HPT灭活更敏感。在酸化样品中TP（90°C，7分钟）和HPTP（600 MPa，90°C，5分钟）后观察到柠檬酸增强了热和HPT的失活以及POD的完全失活，而PPO的最大失活是60％在这些条件下观察到的。在同等的酶失活条件下，TP导致酸化样品的颜色保留比HPTP更好。

行业相关性

本研究调查了在有柠檬酸和无柠檬酸的条件下进行高温高压热处理对梨泥中氧化酶活性和相关品质属性的影响。柠檬酸抑制酶促褐变，保护多酚抗氧化剂免受氧化降解，当以2％（w / w）添加时，柠檬酸的抗氧化能力提高了50％。经过酸化处理的梨泥由于其氧化酶活性降低，pH值低，抗氧化能力强和出色的保色性，因此可以在经过高温或高压热处理后用作酸奶，果酱和婴儿食品等产品中的成分。