均质工艺对苹果浊汁品质的影响

利用不同均质压力(0、10、20、30和40MPa)、均质次数对苹果浊汁进行均质,研究均质工艺对苹果浊汁的褐变情况、悬浮稳定性的影响,还对果汁中果肉颗粒的大小、果汁粘度这两个影响果汁悬浮稳定性的因素进行了探讨。实验结果表明,在30MPa下均质一次可以得到最理想的苹果浊汁。      

苹果浊汁加工中果实成熟度的选择

以生理成熟和完全成熟 2种成熟度的苹果为原料制取浊汁 ,对苹果汁的褐变情况、苹果汁PPO酶的热失活条件、浊汁理化性状以及悬浮稳定性进行比较 ,试验结果表明 :完全成熟的苹果更适宜用作制取浊汁的原料。文中还就苹果果肉细胞的微观形态、影响悬浮稳定性的因素进行了探讨 ,以深入探究完全成熟的苹果更加适宜制取浊汁的机理。     

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。     

加工过程对NFC苹果浊汁营养品质的影响

NFC(非浓缩还原)果汁因其丰富的营养而受到普遍关注。以国光苹果为原料,经打浆、酶解、过滤和杀菌等工艺环节制备NFC苹果浊汁,探讨主要加工环节对苹果浊汁营养品质的影响。结果表明:加工过程中苹果浊汁可溶性糖和还原糖逐渐上升;可溶性蛋白以及果胶含量逐渐下降;可溶性固形物、多酚以及黄酮含量呈先升高后下降的趋势。苹果浊汁加工过程中,多项营养指标间的变化显著相关。酶解过程对可溶性蛋白和可溶性果胶影响较大;过滤过程对蛋白、果胶、黄酮等颗粒构成物的影响较大;杀菌过程使总酚、黄酮等生物活性物质明显减少。旨在为NFC苹果浊汁加工过程中营养素的保持提供理论借鉴,为国光苹果的加工技术应用奠定理论基础。     

高压均质技术结合VC处理对桃浊汁微生物和品质的影响

研究了高压均质技术结合VC处理对桃浊汁中菌落总数、霉菌、酵母菌等微生物指标和pH、可溶性固形物、色泽、总酚和黄酮等品质指标的影响,旨在为桃浊汁高压均质技术的商业化应用提供理论依据。桃浊汁添加0.15% VC后,经压力0～190 MPa,进料温度30,45,60 ℃的高压均质处理后,测定其微生物和品质的变化。结果表明：随着均质压力的升高,桃浊汁中菌落总数、霉菌和酵母菌降低;进料温度升高,会显著提高微生物的杀灭效果,当处理压力110 MPa及以上,进料温度60 ℃时,处理后的桃浊汁中未检测到霉菌和酵母菌。在桃浊汁中添加VC后进行高压均质处理,pH值和可溶性固形物没有显著变化;色泽显著改善,L*值和b*值升高,a*值降低,与未添加VC的样品相比,高压均质处理后ΔE值显著降低,保留了桃浊汁原有的色泽;桃浊汁中总酚和黄酮含量均显著提高,是未添加VC桃浊汁的2～3倍。结论：高压均质结合VC处理可显著降低桃浊汁中微生物,同时抑制果汁褐变,提高总酚和黄酮等营养物质。     

亲水胶体及均质对枣浊汁饮料稳定性的影响

为了提高枣浊汁饮料的稳定性,以浊度保留率、感官评定和Zeta电位为指标,考察多种天然亲水胶体和均质对饮料稳定性的影响.通过加速贮藏试验发现:0.04%(m/V)黄原胶+0.04％(m/V)酸性羧甲基纤维素钠的稳定效果较好.通过测定浊度保留率确定最佳均质工艺条件为50℃均质1次,均质压力为25 MPa.黄原胶和酸性羧甲基纤维素钠组合以及适当的均质可以提高鲜枣浊汁饮料稳定性.     

苹果浊汁云状颗粒体系稳定机制研究进展

苹果浊汁营养丰富且具有多种生理活性,而稳定性不佳一直是制约苹果浊汁产业发展的主要因素之一。本文综述了苹果浊汁云状颗粒体系的构成,云状颗粒物的聚集和失稳过程,以及影响云状颗粒体系稳定的主要因素,并对云状颗粒体系稳定机制的研究方向进行了展望。本研究可为维持苹果浊汁云状稳定性,提高其贮藏品质,推动苹果浊汁产业快速发展提供一定的思路和借鉴。     

基于品质指标的苹果浊汁品种与产地差异性分析

以来自7?个不同主产区的21?个主栽品种,共41?份苹果鲜果为研究对象,对每个品种鲜榨浊汁的出汁率、浊度、果汁颜色、褐变度、透光率、可溶性固形物、可滴定酸、总酚、糖、有机酸、VC、矿物质、抗氧化性等品质指标进行测定。运用描述性分析、逐步线性判别分析进行数据处理。结果表明：不同品种或不同产地的苹果浊汁,品质差异较大。总体来看,a*值、原始浊度、褐变度、可滴定酸、葡萄糖、蔗糖、苹果酸等指标的变幅均较大,分别为94.07%、70.41%、42.86%、35.26%、42.02%、42.40%、37.69%。对于不同品种的苹果浊汁,由于褐变度、总酚、抗氧化性等色泽品质指标以及糖、酸等营养品质指标间具有较大差异,其分布呈现分散状态。其中新红星品种的褐变度、总酚含量、DPPH自由基清除率等品质指标普遍居高,色泽品质差异最显著。富士品种大部分样品的果糖、葡萄糖、蔗糖、苹果酸等指标含量较高,具有较好的营养品质。然而对于不同产地间的样品,其浊度、可滴定酸、可溶性固形物等加工品质指标具有较大差异,样品分布较为分散。河北省样品的出汁率、原始浊度、可滴定酸等指标普遍较低,加工品质较差。来自山东省不同品种苹果浊汁的样品以及来自不同产地富士苹果浊汁的样品间均具有较大差异,并且分别获得了77.8%和72.7%的判别准确率。以上结果表明,不同产地、不同品种苹果原料制得的苹果浊汁存在较大差异,通过对其品质指标进行差异性分析,可为上游育种与种植产业结构调整提供数据基础;通过判别模型的建立实现品种与产地的识别与预测,可以指导企业对苹果原料进行制汁专用化筛选。     

NFC苹果浊汁褐变与品质相关性研究

褐变是果汁品质劣变的重要因素之一.通过模拟NFC苹果浊汁开封后在未完全密闭状态下,于4℃和20℃短期贮藏期间的自然褐变过程,探讨苹果浊汁褐变过程与营养及风味变化的关系.结果表明,NFC苹果浊汁贮藏过程中褐变程度受贮藏温度和时间的直接影响.在两种贮藏温度下,果汁颜色均随贮藏时间延长不断加深,总酚和维生素C含量逐渐下降;可溶性固形物含量降低和可滴定酸含量增高导致糖酸比下降.20℃贮藏期间,果汁品质劣变迅速;4℃贮藏初期,果汁品质变化不明显,但在后期劣变速度明显加快.NFC苹果浊汁在贮藏前期芳香族化合物、氮氧化合物等挥发性风味物质有所减少,而在贮藏后期碳氢化合物、无机硫化物、烷烃类和脂肪族类物质逐渐增加.褐变与NFC苹果浊汁品质指标的相关性分析表明:冷藏条件下褐变程度与浊汁口味和挥发性风味的相关性更强,而常温贮藏下与浊汁营养物质含量的相关性更强.研究结果可丰富果汁贮藏机理,以期为苹果浊汁加工及开封后短期贮藏过程中品质变化研究及调控提供理论借鉴.     

Safety and quality assessment during the ozonation of cloudy apple juice

Traditionally, ozone processing within the food industry has focused on solid foods by either gaseous treatment or washing with ozonized water. However, with the FDA's approval of ozone as a direct additive to food, the potential for liquid applications has emerged. This study investigates the effect of ozone processing on microbial inactivation (E. coli ATCC 25922 and NCTC 12900) and quality parameters (color, phenolic content) of cloudy apple juice. Apple juice samples were ozonated at room temperature (20 ± 1.5 °C) with a generated ozone concentration of 0.048 mg O(3) at a constant flow rate of 0.12 L/min and treatment time of 0 to 10 min. E. coli inactivation kinetics in apple juice were described quantitatively by using the Shoulder log-linear and the Weibull model. Ozone treatment of E. coli in apple juice demonstrate that a desired 5 log reduction can be achieved within 5 min. Apple juice color (L*, a*, and b*) and total phenols were significantly affected by ozone concentration and treatment time.     

High-pressure treatment of cloudy apple juice

A factorial design with four factors (pressure, holding time, temperature and waiting period between crushing of apple and high-pressure (HP) treatment) was built up to study the effect of HP treatment on pectin methylesterase activity (PME, EC 3.1.1.11) in cloudy apple juice. PME activity was measured by the methanol release during the storage of samples at 4 °C for 1 month. Only the holding time of the treatment and three interactions between factors (holding time×temperature, pressure×waiting and holding time×waiting) had significant effects on the PME level. Increasing the pressure or the holding time at moderate temperatures (15-40 °C) increased the activity. PME purified from apple was pressure stable in the range 100-600 MPa at 25 °C. The soluble pectin content was not changed after HP treatment. The particles size increased with the temperature reached during the treatment, in agreement with a diffusion-limited-aggregation model but were independent of pressure and holding time. In a separate experiment we found a positive correlation between the PME activity and the residual content of the catechins suggesting that polyphenoloxidase (PPO, EC 1.14.18.1) and oxidized polyphenols play a role in the PME activity level after HP treatment.     

Effect of ascorbic acid on the odours of cloudy apple juice

Ascorbic acid is used in apple juice as an antibrowning agent. This study investigated the effect of ascorbic acid (0.0–0.2% w/v) on the odours of cloudy apple juice using sensory evaluation and gas chromatography (GC). The increase in ascorbic acid concentration in the apple juice resulted in increases in green and unnatural odours and decreases in fresh, fruity and apple-like odours. In the GC determination, 23 volatile compounds were detected in apple juice. Aroma value, which showed the relative importance of volatile compounds, was used to elucidate the changes in odours of apple juice due to the addition of ascorbic acid. The aroma values of hexanal and trans-2-hexenal in the apple juice with 0.2% w/v ascorbic acid increased about 4 and 5-fold from those in the ascorbic acid-free apple juice, respectively. On the other hand, the aroma values of esters insignificantly changed in the apple juice with ascorbic acid. The increases in aroma values of aldehydes corresponded well with the increase in green odour in the apple juice with ascorbic acid.     

Free and bound patulin in cloudy apple juice

During validation of an HPLC-UV method for patulin analysis, a time and concentration dependent recovery of patulin was observed. Spiked cloudy apple juice was analysed on successive days, which resulted in recoveries on day 3 which were up to 20% lower than on day 1. This reduction was caused by an interaction between patulin and the solid parts of cloudy apple juice. Since these solid parts are richer in proteins compared to the liquid phase of cloudy apple juice, and the binding of patulin to proteins has been described in the literature, patulin will most probably interact with the proteins in the solid parts. As a consequence, up to 20% of the present patulin is bound and not detected during HPLC-UV analysis, which can lead to an underestimation on toxicological level.     

影响浊苹果汁混浊稳定性的因素

对影响混浊苹果汁混浊稳定性的因素进行了综述。总体看来,混浊苹果中可溶性果胶的含量,多酚-蛋白质复合物的形成、酚类的氧化聚合和原花青素的聚合都对悬浮颗粒的尺寸有影响。同时,对今后的研究重点进行了讨论。     

浑浊苹果汁加工中苹果PPO热失活条件的研究

研究了热处理苹果汁(加或不加防褐变剂)、苹果浆使其中的PPO完全及部分失活所需要的温度和时间。结果为:在90℃处理苹果汁15s可使其中的PPO完全失活,而对于苹果浆则需要90℃处理20s以上。加了防褐变剂的苹果汁经90℃处理10s可使其中的PPO完全失活;此外,经80℃处理30s以上虽不能使其中的PPO完全失活,但添加的防褐变剂及果汁自身的pH值可抑制残余的PPO从而防止酶促褐变的发生。70℃处理苹果汁40s不能防止其中的酶促褐变。     

Effect of high hydrostatic pressure on immunomodulatory activity of cloudy apple juice

Present study investigated the effects of high hydrostatic pressure treatment (HHP, 500 MPa/3 min/ 25°C) on bioactive compound as well as antioxidant, immunomodulatory potentials, and microbial safety of cloudy juice from ‘Fuji’ apples. HHP did not cause any significant changes in vitamin C content whereas total polyphenol content was increased. The antioxidant potentials measured by DPPH and nitric oxide (NO) radical scavenging tests were preserved by HHP, while thermal treatment reduced antioxidant potentials. NO scavenging activity was greater than DPPH scavenging activity. The immunomodulatory effect assessed by splenocyte proliferation was increased in a dose-dependent manner, and HHP preserved immunomodulatory activity of apple juice. Furthermore, HHP treated juice was microbiologically safe without any physicochemical changes during 21 days of storage at 4°C. These results demonstrated the efficacy of HHP for preserving both nutritional and immunomodulatory functional characteristics of apple juice, and alternative method for preserving as freshly squeezed for up to 21 days.     

辐照处理对混浊苹果汁有机磷农药降解的影响

研究了辐照处理对混浊苹果汁的品质和降解有机磷农药（毒死蜱、敌敌畏、乙酰甲胺磷、氧化乐果）的作用,并对果汁颜色、V C含量和总酚含量等的变化进行了研究。有机磷农药的测定参考农业部标准（NY/Y761-2004）,并略作改进。结果表明,辐照降解有机磷农药效果较好,降解率从大到小依次为毒死蜱、敌敌畏、乙酰甲胺磷、氧化乐果。辐照剂量小于6kGy时对混浊苹果汁品质无显著负面影响。      

混浊苹果汁加工过程中的的酶促褐变及其防止的研究

将几种可用于食品的防褐变剂在苹果破碎时加入,考察了它们对苹果浆和苹果鲜榨汁的防褐变效果及它们之间的协同作用.半胱氨酸、抗坏血酸、曲酸、氯化钠和氯化钙都是较好的防褐变剂.在所测试条件下,抗褐变的能力(褐变抑制率)为0.1%的抗坏血酸＞0.1%的偏重亚硫酸钠＞0.1%的曲酸＞0.1%的氯化钙＞0.005%半胱氨酸＞0.1%氯化钠.它们抗褐变能力都表现为浓度依赖型,特别是抗坏血酸.柠檬酸在所测试条件下没有抗褐变效果.0.044%NaCl+0.0125%Vc的组合较经济且可使果汁40min不变色.果浆脱气可减缓其褐变;减小果汁及果浆与空气的接触面也可防止褐变.     

混浊苹果汁加工过程中的酶促褐变及其防止的研究

将几种可用于食品的防褐变剂在苹果破碎时加入,考察了它们对苹果浆和苹果鲜榨汁的防褐变效果及它们之间的协同作用。半胱氨酸、抗坏血酸、曲酸、氯化钠和氯化钙都是较好的防褐变剂。在所测试条件下,抗褐变的能力（褐变抑制率）为:0.1％的抗坏血酸>0.1％的偏重亚硫酸钠>0.1％的曲酸>0.1％的氯化钙>0.005％半胱氨酸>0.1％氯化钠。它们抗褐变能力都表现为浓度依赖型,特别是抗坏血酸。柠檬酸在所测试条件下没有抗褐变效果。0.044％NaCl+0.0125％Vc的组合较经济且可使果汁40min不变色。果浆脱气可减缓其褐变;减小果汁及果浆与空气的接触面也可防止褐变。