为士果胶酶加工砀山酥梨浓缩清汁的应用

酶制剂在加工果蔬浓缩清汁方面起着重要的作用,酶制剂的功能影响着果蔬汁质量的好坏,现对为士果胶酶在线生产砀山酥梨清汁的研究,说明该种酶制剂结合其他工艺条件表现出来的功能,结果表明,可以提高产品色值稳定性,提高生产过程超滤通量,降低产品浊度。     

浓缩苹果清汁色值测定影响因素分析

色值是反映浓缩苹果汁颜色深浅程度和衡量苹果浓缩清汁产品质量的重要理化指标。介绍了浓缩苹果汁色值测定的意义、色值测定的检测仪器和主要测定方法,重点研究了影响浓缩苹果清汁色值测定结果准确性的几个因素。     

苹果啤酒酿造工艺的研究

用苹果汁与麦芽汁混合发酵 ,酿制苹果啤酒。榨出的苹果汁用 6 0mg/L的SO2 抑菌、护色 ,50 g/t的果胶酶脱胶 ,1 2 5g/L的皂土澄清 ,清汁与麦芽汁混合。苹果汁的添加比以 30 %为佳。发酵度在 6 0 %～ 6 5%时 ,酿出的成品啤酒具有突出的苹果香、麦芽香及酒花香 ,三香协调 ,口味纯正柔和 ,酸度适宜 ,保质期在 12个月以上     

砀山酥梨浓缩汁生产中的褐变类型研究

研究了浓缩砀山酥梨清汁生产的褐变类型。对70Brix的浓缩砀山酥梨清汁各加工工序中的色值、总酚，氨基酸态氮、5-羟甲基糠醛（5-HMF）、多酚氧化酶（PPO）相关指标进行检测，分析褐变机制。结果分析表明，在整个加工过程中，预浓缩工序之前的褐变主要是酶促褐变，预浓缩后至超滤之间的褐变是酶促褐变和非酶促褐变共同作用的结果，超滤之后的褐变则完全是非酶促褐变。     

膜技术在苹果汁加工中的应用

应用平板式超滤技术对苹果浊汁进行了过滤澄清和除菌。研究了巴式杀菌酶解或未酶解的苹果浊汁、未巴式杀菌未酶解的苹果浊汁、温度对膜通量的影响,超滤组件形式、操作参数对3种不同预处理料液的滤液质量的影响及反渗透系统的浓缩效果。结果表明:平板式超滤膜通量能满足工业需求且大于管式超滤膜,操作温度宜为50℃,当加水倍数0.09倍时,可使浓缩倍数达到20倍。苹果汁超滤液的透光率在97%以上、色值在50%以上、浊度指标小于0.3,pH值、总酸、糖度、氨基态氮等却未发生明显的变化。苹果汁超滤液质量指标和耐热细菌检查结果比较表明,平板式超滤可代替对苹果汁巴式杀菌及酶解。反渗透系统对苹果汁超滤液进行浓缩,浓缩倍数为2～2.3倍,糖截留率为100%。     

浓缩苹果汁加工中酶作用及贮藏稳定性研究

以红富士苹果浓缩汁为材料,采用单因素试验,研究果胶酶和α- 淀粉酶对还原糖、总酸、可溶性固形物等几个指标的影响,同时找出适合浓缩苹果汁澄清的果胶酶和α- 淀粉酶的酶用量、温度和时间。实验结果表明,在酶用量0.1%、温度50℃、时间1.5h 的条件下,浓缩苹果汁的澄清效果较明显。将加入果胶酶和α- 淀粉酶的浓缩苹果汁置于4℃和26℃条件下贮藏,测定其在贮藏过程中还原糖含量、总酸含量、pH 值和透光率等指标的变化。结果表明,在4 ℃贮藏条件下,随着贮藏时间的延长,还原糖含量、总酸含量、pH 值、透光率变化幅度较小,果汁营养成分保持较好,适宜贮藏。     

树脂对浓缩苹果清汁色值调控研究

以半成品浓缩苹果清汁为试材,检测透光率和色值,选取3种不同类型和4种不同配比树脂,研究25℃条件下果汁色值及其稳定性,旨在提高色值以减轻褐变程度。结果表明,脱色能力:LSA-900ELSA-900BLSA-900C,LSA-900B∶LSA-900E=1∶3LSA-900B∶LSA-900E=1∶4LSA-900B∶LSA-900E=1∶2LSA-900B∶LSA-900C=1∶4。单独使用树脂时维持果汁色值稳定性的能力差异不明显,而LSA-900B∶LSA-900E=1∶3树脂对果汁稳定性的调控效果最佳。     

棒曲霉素脱除树脂对苹果清汁质量指标的影响

试验对冬富士苹果清汁中棒曲霉素(Pat)脱除用的8种型号大孔吸附树脂静态吸附、解吸率进行了比较,方差分析选定LSA-900B、LS-803和XDA-600为优选树脂,检测了这3种树脂处理后苹果清汁的吸光度、色值、透光率、浊度、糖度和酸度变化。结果表明:3种型号树脂在50℃下对苹果清汁中Pat静态吸附率分别达到92.55%、90.67%和89.01%,其组间差异不显著(P<0.05);3种树脂经乙酸乙酯对Pat洗脱,静态解吸率分别达到75.91%、58.37%和75.67%,组间差异也不显著(P<0.05);经3种树脂处理后,4项正相关影响指标的波动幅度依次为浊度>吸光度>色值>透光率(α=0.01);2项负相关影响指标的波动幅度酸度>糖度(α=0.01)。     

固定化果胶酶提高苹果出汁率的研究

采用固定化果胶酶处理红富士苹果浆,在苹果浆pH值、固定化果胶酶水解温度、固定化果胶酶使用质量和固定化果胶酶水解时间对苹果浆出汁率的影响等单因素试验的基础上,采用响应面法分析,探索固定化果胶酶提高苹果浆出汁率的最佳条件。最佳工艺条件为苹果浆适宜pH3.43、固定化果胶酶与苹果浆质量比为1:15、酶促反应温度49.4℃、酶促反应时间3.50h。固定化果胶酶反复使用10次时,苹果浆的出汁率为62.421%,与对照组相比仍提高约13%。     

HACCP在浓缩苹果清汁生产中的应用

本文运用HACCP 原理对浓缩苹果清汁生产过程进行了危害分析及关键控制,确定了其关键控制点为:原料果和无菌包装材料的验收、原料果拣选、后巴氏杀菌和无菌灌装。通过对关键控制点的监控确保苹果清汁的质量。     

苹果汁的前褐变及苹果PPO的部分特性研究

苹果汁贮藏过程中色泽加深、色值和透光率不稳定是苹果汁生产中普遍存在的问题,文中尝试采用苹果自身的PPO进行前褐变反应,以减少果汁中的酚类化合物,防止后期褐变。研究表明,果汁经30℃前褐变反应4 0min后,总酚质量含量可下降约30 % ,可溶性固形物质量分数提高了2 8% ,常温下贮藏3个月后,色值和透光率基本保持不变,明显地改善了苹果汁的质量指标。同时,文中还探讨了PPO的最适pH值、最适反应温度及其pH稳定性、热稳定性等性质     

Synthesis of octadecyl acrylate-co-ethylene glycol dimethacrylate resin for removal of dark-colored compound from apple juice and comparison with polyvinylpolypirrolidone (PVPP)

Adsorption process has an importance for improving the color of juice and also stabilizing the final product during the shelf life. In this study, polyvinylpolypirrolidone (PVPP) and octadecyl acrylate-co-ethylene glycol dimethacrylate (ODA-EGDMA) polymeric resins were used as adsorbents for improving the color properties of apple juice. The ODA-EGDMA resin was prepared by classical suspension polymerization technique and characterized by electron microscopy. The obtained spherical particles diameters were between 20 and 140 μm. PVPP was selected as reference polymeric material for its importance in the juice industry. The adsorption kinetics of dark-colored compounds on adsorbent polymeric resins were studied at different adsorbent resins concentrations (1, 2, 4, and 8 g adsorbent resin per liter of apple juice) at the constant temperature (20 °C) in batch reactor. Langmuir adsorption model was applied for both PVPP and ODA-EGDMA polymeric adsorbents. The Langmuir isotherms were plotted for both polymeric adsorbents by evaluation of the absorbance data of apple juice at 420 nm. Langmuir isotherm's empirical constants known as K _ad and Q ₀ were calculated from the equilibrium data. Numerical value of K _ad and Q ₀ were determined as 5.0578 and 0.3089 for the ODA-EGDMA polymeric resin, 2.4824 and 0.5268 for the PVPP adsorbent, respectively. The scope of this study included comparison of reusability and regeneration properties of the each polymeric adsorbent. For this purpose, series of experiment were done in pack bed column application. Pressure drop measured throughout the PVPP pack bed column was 4.8 times higher than ODA-EGDMA pack bed column at same flow rate (2.5 mL/min) during the this group experiment. ODA-EGDMA resin and PVPP were regenerated with NaOH (4% w/v, 50 °C) after each run. After regeneration, average removal of dark color (relative absorbance change at 420 nm) of apple juice was determined as 76.47±0.90% for ODA-EGDMA and 91.51±0.86% for PVPP adsorbent resin.     

沿面放电等离子体对苹果汁中耐高渗酵母的杀灭效果

目的：研究沿面放电等离子体对苹果汁中耐高渗酵母（Zygosaccharomyces rouxii）的杀灭效果及其对苹果汁品质的影响。方法：以耐高渗酵母LB为目标菌株，首先利用不同电压和不同气体流速沿面放电等离子体处理目标菌株，通过微生物技术分析沿面放电等离子体对目标菌株的杀灭效果，并观察处理过程对细胞膜的破坏作用；其次，评估沿面放电等离子体处理对苹果汁理化指标及色泽和挥发性化合物的影响。结果表明：在21 kV等离子体处理30 min后，500 mL 苹果汁中的耐高渗酵母数量降低了5.60 个对数，并且等离子体处理会造成细胞膜损伤，从而导致细胞死亡。沿面放电等离子体处理对苹果汁理化指标和挥发性化合物总体没有显著影响（P＞0.05），但处理前后苹果汁颜色参数变化显著（P＜0.05）。结论：沿面放电等离子体对苹果汁中耐高渗酵母具有显著的杀灭效果，研究结果可为该技术应用于食品中微生物的杀灭提供理论依据。     

Effect of High Hydrostatic Pressure on Cashew Apple (Anacardium occidentale L.) Juice Preservation

ABSTRACT:  High hydrostatic pressure is an alternative to thermal processing to inactivate spoilage and pathogenic microorganisms. Cashew apple juice has a pleasant flavor and is rich in vitamin C. Studies to determine the effect of high pressure on microorganisms in cashew apple juice are still lacking. In this study, the inactivation of natural micropopulation and inoculated Escherichia coli by high pressure was evaluated in fresh cashew apple juice. The microbiological stability of pressure-treated juice was also evaluated. The applied high pressure levels ranged from 250 to 400 MPa for periods of 3 to 7 min. Treatments with 350 MPa for 7 min and 400 MPa for either 3 or 7 min reduced the aerobic mesophilic bacteria count to a level below the detection limit. Pressure treatments were also efficient in inactivating yeast and filamentous fungi. The inoculated E. coli (10⁶ CFU/mL) was reduced to below 10 CFU/mL after a pressure treatment of 400 MPa for 3 min. The inactivation of this microorganism followed a 1st-order reaction kinetics. The decimal reduction time ( D- value) ranged from 1.21 to 16.43 min, while pressure resistance value ( z -value) was 123.46 MPa. Neither natural micropopulation growth nor E. coli repair was observed in postprocessed (400 MPa for 3 min) cashew apple juice kept under refrigerated storage (at 4 °C) during 8 wk. The results of this study demonstrated the efficacy of high-pressure treatment for preserving cashew apple juice.     

活性炭吸附对苹果汁色值的影响

为了提高苹果汁的色值,采用活性炭吸附.分别考察了活性炭目数,活性炭添加量,吸附温度对色值的影响.得出最佳的吸附目数和添加量组合是:80目,添加量为0.015g/mL.吸附温度对果汁色值的影响是温度越高,果汁色值越低.     

苹果浓缩汁非酶褐变动力学及影响因素

通过检测苹果汁的色值(T440nm)、褐变指数(A420nnm)、氨基态氮、5- 羟甲基糠醛含量等指标研究加工过程对苹果汁褐变的影响以及在不同贮藏温度(5、20℃和37℃)下苹果浓缩汁(70.5°Brix)的非酶褐变速率。3 个贮藏温度下的苹果浓缩汁褐变速率均符合一级反应动力学模式,而且高温情况下褐变更明显。随着贮藏时间的延长,氨基态氮含量明显下降而5- 羟甲基糠醛含量上升,尤其是贮藏在37℃的苹果汁这一变化更明显。5- 羟甲基糠醛与果汁褐变效应呈指数关系,可以说明苹果汁在贮存中的褐变主因是发生美拉德反应,而且氨基态氮含量与果汁褐变效应的线性关系也验证了这一结论。在果汁的初始加工过程中,破碎、压榨、酶解、超滤、前巴氏杀菌等单元操作中美拉德反应并不明显;吸附操作可以去除果汁中的氨基态氮以及其他色素物质;而其他操作过程如浓缩和后巴氏杀菌则促进了美拉德反应,导致果汁氨基态氮含量明显下降。     

Comparing the impact of high pressure,pulsed electric field and thermal pasteurization on quality attributes of cloudy apple juice using targeted and untargeted analyses

The impact of low-oxygen spiral-filter press technology combined with thermal pasteurization (TP), pulsed electric field (PEF) and high pressure processing (HPP) on cloudy apple juice quality was investigated immediately after the treatments and after 3 weeks of storage at 4 °C. Based on equivalent levels of microbial safety and desired shelf-life, low and high processing intensities were selected: TP (72 °C/15 s; 85 °C/30 s), PEF (12.5 kV/cm, 76.4 kJ/L; 12.3 kV/cm, 132.5 kJ/L), and HPP (400 MPa/3 min; 600 MPa/3 min). High intensity thermal treatment resulted in a bright, yellowish color which was maintained during storage. PPO and POD activities were largely reduced by high intensity PEF and TP yet showed high resistance to HPP. The highest vitamin C content was provided by fresh juice followed by PEF-treated juices. Due to oxidative degradation reactions, vitamin C of all treated samples significantly decreased during storage. Immediately after processing, high cloud stability values were obtained in all samples; however, cloud stability decreased during storage particularly for HPP juices with high residual PME. No significant changes were observed in pH, titratable acidity, organic acid and sugar content which also corresponded to sweet and sour taste. Results from untargeted volatile profiles showed that esters increased after PEF and were better retained after HPP. Contrary to TP treatment where ester degradation reactions occurred together with the formation of off-flavors. Most of the volatiles decreased during storage which could be linked to oxidation and ester hydrolysis reactions.Industrial relevanceBeing one of the most popular fruit juices consumed worldwide, cloudy apple juice can still undergo quality changes such as color degradation, cloud loss (fast sedimentation) and flavor changes during processing and storage. This study evaluates the potential of low-oxygen spiral-filter press in combination with different preservation technologies to obtain a maximal quality of cloudy apple juice. Results showed that high intensity thermal pasteurization can effectively inactivate quality-degrading enzymes, therefore it is useful to obtain an optimal cloudy apple juice product in terms of color and cloud stability. Although HPP has minimal impact on aroma of the juice, shelf-life of the juice may be limited due to incomplete enzyme inactivation. In the case of PEF treatment, thermal effects may contribute to maintain apple juice quality.     

Improved Ultrafiltration for Color Reduction and Stabilization of Apple Juice

Polyphenols that are responsible for haze-formation and browning during storage of clear apple juice and concentrates could be selectively removed by an ultrafiltration process using membranes of polyether sulfone and polyvinylpyrrolidone. Results were compared with those from commercial UF membranes made out of regenerated cellulose acetate. The effects of laccase treatment on removal of polyphenols and color in apple juice were also investigated. Custom membranes were effective to reduce the amount of polyphenols. A remarkable desired color removal of apple juice could also be achieved using these membranes. Resulting products were stable in color and clarity at 50°C up to 6 wk. Laccase treatment increased the percentage removal of polyphenols from apple juices. However, laccase treated samples were more susceptible to coloration and haze-formation during storage.