高压均质对NFC水蜜桃浊汁稳定性及品质的影响

本文采用高压均质技术，探究了均质压力（20~40 MPa）及次数（1~2次）对NFC水蜜桃浊汁的混浊度、离心沉淀率、粒径、Zeta电位等稳定性指标和pH、TSS、总酸、固酸比、还原糖、色泽、总酚、V_C等品质指标的影响。结果表明:高压均质（30~40 MPa/1、20~40 MPa/2）可有效提高NFC水蜜桃浊汁的稳定性，离心沉淀率较未处理组下降13.49%~24.22%，平均颗粒粒径由1853.67 nm降至501.10~665.27 nm，绝对Zeta电位值显著提高（P<0.05）。随着均质压力及次数的增加，浊汁中可溶性果胶含量上升，而残存果胶甲基酯酶活力逐渐降低。高压均质后，浊汁色泽显著改善，L*值升高，褐变指数BI值下降（P<0.05）；30 MPa/1下，品质保持最佳，总酚、V_C含量较未处理组显著提高（P<0.05），而pH、TSS、总酸和固酸比无变化（P>0.05）；随着均质次数增加，pH、TSS、总酚和V_C含量显著降低（P<0.05），品质下降。高压均质处理可有效提高NFC水蜜桃浊汁稳定性、抑制褐变，并提高总酚、V_C等营养物质含量。

Effect of High Pressure Homogenization on the Stability and Quality of Not-From-Concentrate Cloudy Honey Peach (Prunus persica L.) Juice

In order to determine the effect of high pressure homogenization (HPH) on the stability and quality of not-from-concentrate (NFC) cloudy honey peach juice, the samples were subjected to HPH processing with 20~40 MPa for 1~2 successive passes. The changes in turbidity, centrifugation precipitating rate, particle size distribution, Zeta potential, water soluble pectin content, pectin methylesterase (PME) activity, pH, total soluble solids (TSS), total acidity (TA), TSS/TA, reducing sugar content, color, total phenol and V_C content were evaluated. The results showed that HPH could effectively improve the stability of NFC cloudy honey peach juice. With the treatment of 30~40 MPa/1 and 20~40 MPa/2, the centrifugation precipitating rates significantly decreased by 13.49%~24.22% (P<0.05), while the mean particle diameter decreased from 1853.67 nm to 501.10~665.27 nm, as compared to that in untreated samples. Moreover, the absolute Zeta potential significantly increased (P<0.05). As the pressure and successive pass increased, the water soluble pectin content tended to increase, while the PME activity gradually decreased. HPH observably increased the L* value of cloudy peach juice, and reduced its browning index (P<0.05), indicating the color of NFC cloudy peach juice was markedly improved. Juice homogenized at 30 MPa/1 showed the best quality. The contents of total phenol and V_C were significantly enhanced (P<0.05), whereas no change was found for pH, TSS, TA and TSS/TA levels (P>0.05). HPH decreased the pH, TSS, TA, total phenol and V_C content with increasing pass number (P<0.05), leading a decline in juice quality. HPH treatment could dramatically improve the stability of NFC cloudy peach juice, and inhibit browning and improve its total phenol and V_C levels.