超高压鲜榨梨汁褐变因素与控制研究

分析超高压鲜榨梨汁褐变的影响因素,探索褐变控制技术,以翠冠梨汁为对象,研究了成熟度、澄清、去心、柠檬酸、抗坏血酸处理对梨汁褐变的影响,测定了色泽、总酚、多酚氧化酶、糖度、酸度、pH值等指标。结果表明,八九成熟的翠冠梨榨汁不易褐变;300~600 MPa超高压处理会加速梨汁货架期褐变;PPO活性和总酚含量是影响鲜榨梨汁褐变的主要因素,而pH值是影响PPO活性的一个重要因素;澄清处理、去心处理可以降低PPO活性和总酚含量,一定程度上抑制梨汁褐变;柠檬酸会降低pH值,更接近PPO最适反应pH值,提高PPO活性,加速梨汁褐变;抗坏血酸可有效抑制PPO活性,防止梨汁褐变。因此,抗坏血酸是一种有效控制超高压梨汁褐变的方法。

Study on Browning Factors and Control Technology of High Pressure Processing on Fresh Pear Juice

To analyze the influencing factors of fresh pear juice browning after high pressure processing treatment and explore the control technology,taking Cuiguan pear juice as materials,the effects of maturity,clarification,coring,citric acid and ascorbic acid treatment on browning of fresh pear juice were studied.The color,total phenol,polyphenol oxidase,sugar degree and acidity were determined.The results showed that the juice squeezed from Cuiguan pear of 80%and 90%maturity was not easy to brown;300~600 MPa high pressure processing treatment could accelerate the browning of pear juice in shelf life;PPO activity and total phenol content were the most critical factors affecting the browning,and pH value was an important factor affecting PPO activity.Clarification and coring could reduce PPO activity and total phenol content,inhibit browning of fresh pear juice to a certain extent;citric acid could accelerate browning of pear juice,so it should be used as acidity regulator rather than as anti-browning agent;ascorbic acid could inhibit PPO activity and effectively prevent browning of fresh pear juice after high pressure processing treatment.