Pulsed Ultra High Pressure Treatments for Pasteurization of Pineapple Juice

Sinusoidal and step-pressure pulses were compared with static pressure treatments for the inactivation of Saccharomyces cerevisiae 2407-1a in pineapple juice. No inactivation was observed after 40–4,000 fast sinusoidal pulses (10 cycles/s) at 4–400 sec in the 235–270 MPa range. Static 270 MPa treatments at 40 and 400 sec resulted in 0.7 and 5.1 decimal reductions, respectively. Slower 0–270 MPa step pulses at 0.1 (10 pulses), 1 (100 pulses), and 2 (200 pulses) cycles/s with 100 sec total on-pressure time resulted in 3.3, 3.5, and 3.3 decimal reductions, respectively. A comparable static pressure treatment resulted in 2.5 decimal reductions. Changing the on-pressure/off-pressure time ratio (3:1, 3:3 and 1:3) showed that treatments with longer on-pressure time, e.g., 0.6 sec on-pressure and 0.2 sec off-pressure were significantly more effective showing nearly a 4 decimal reduction in 100 sec.     

高静压工艺中单元操作对草莓汁饮料中抗氧化物质含量与抗氧化活性影响

研究高静压工艺中单元操作草莓浊汁饮料和清汁饮料中的主要抗氧化物质及抗氧化活性的影响。结果表明,蒸汽热烫1min使草莓中VC损失7.3%,花色苷损失18.82%,总酚含量没有明显变化,DPPH自由基清除能力和FRAP铁离子还原能力分别降低了8.14%和8.49%;离心后VC、花色苷、总酚、DPPH和FRAP分别损失50.64%、46.35%、49.34%、35.45%和39.72%;酶解对花色苷、VC和多酚含量及抗氧化活性均无显著影响;超高压处理后浊汁饮料和清汁饮料VC各降低7.8%和12.6%,但花色苷、总酚和抗氧化活性无显著变化。     

沙棘果汁营养成分及保健作用

综述了近几十年来国内外关于沙棘果汁中各种成分的营养价值和保健作用及其研究进展,表明沙棘果汁不仅具有巨大的营养价值还具有重要的药用价值。     

贮藏条件对超高压处理蓝莓汁酚类物质及抗氧化活性的影响

以经超高压处理（400MPa／IOmin）的鲜榨蓝莓汁为对象,研究其5周内在4℃、25℃、37℃贮藏条件下总酚、总黄酮、花色苷含量和抗氧化能力的变化。结果表明：随贮藏时间的延长,在以上三个贮藏温度下,总酚含量和抗氧化能力均呈显著下降趋势（p〈0．05）,总黄酮含量无显著变化,花色苷含量显著下降（p〈0．05）,且其降解过程符合一级反应动力学模型,其反应的活化能Ea为55．75kJ／mol;抗氧化能力与总酚和花色苷含量显著相关。4℃贮藏条件下抗氧化能力与总黄酮含量无显著相关,25℃、37℃下则呈负相关。此外颜色分析显示不同储藏温度下蓝莓汁a·值、b＋值、C值随贮藏时间的延长上升,L＋值下降,37℃下贮藏4周后蓝莓汁的色差△E〉2,已对其感官质量造成影响。由此表明低温短时贮藏有利于保特蓝莓汁中酚类物质含量及抗氧化活性。     

正交试验法优化沙棘籽油的提取工艺

采用溶剂法提取沙棘籽油,以沙棘籽油的提取率为目标,在单因素试验的基础上,以石油醚(60℃～90℃)为提取溶荆,选取料液比、原料粒度、提取时间为影响因素,用正交试验优化沙棘籽油的提取工艺.结果表明沙棘籽油的最佳提取工艺为:提取溶剂为石油醚(60℃~90℃),原料粒度60目~80目,料液比1:10(g/mL),温度为85℃,提取时间为8 h,此时沙棘籽油的得率为12.56%.     

超高压处理对梨汁中多酚氧化酶活性的影响

目的研究鲜榨梨汁中多酚氧化酶(PPO)的活性受高压和热协同处理的影响。方法使用超高压技术单独或协同加热处理加或不加维生素C的鲜榨梨汁,测定其中PPO活性和果汁颜色。结果200～600MPa的压力处理对果汁中PPO活性影响不大,400MPa的压力对PPO有激活作用;高于600MPa的压力使PPO显著失活。维生素C在500MPa以下对果汁中PPO有激活作用,在600MPa以上或热处理结合高压时有钝化PPO的作用。随着保压时间延长和温度升高,梨汁中PPO相对活性逐渐降低。500MPa60℃或750MPa50℃以上的处理条件可使鲜榨梨汁中的PPO失去60%以上的活性,750MPa50℃的处理条件下果汁颜色变化不显著。结论梨的PPO是耐高压的酶。     

瞬时高压处理对α-淀粉酶活性的影响

研究了不同条件下瞬时高压处理时α-淀粉酶活性的影响。结果表明：瞬时高压作用对α-淀粉酶具有有效的钝化作用，在pH6时，25℃、35℃、45℃下分别处理1次，80-120MPa时α-淀粉酶活性下降较慢，120MPa后活性下降变快；提高进料温度，可以增强瞬时高压对α-淀粉酶的钝化效果。pH6、25℃时，在100MPa、120MPa和140MPa下分别对α-淀粉酶处理3次，在相同的作用压力下，α-淀粉酶活性随处理次数的增加呈下降趋势：α-淀粉酶活性降低幅度随处理次数的增加而变小。常压下α-淀粉酶在pH值5．0～8．0时较为稳定，pH值低于4时严重失活；120MPa下，α-淀粉酶活性较常压下低；活性下降幅度在强酸时更大，其次为强碱，pH6时最小。     

超高压提取青钱柳多糖条件优化及抗氧化活性

试验以青钱柳叶为原料,研究青钱柳多糖的超高压提取工艺,对提取的青钱柳粗多糖进行抗氧化活性试验。采用单因素及正交试验对青钱柳多糖的超高压提取工艺进行优化,结果显示,青钱柳多糖最佳提取条件为:料液比1︰25(g/mL)、提取温度30℃、提取压力500 MPa。在此条件下,青钱柳多糖得率最高,为3.70%。将青钱柳粗多糖进行清除DPPH自由基、清除羟基自由基试验,以抗坏血酸(VC)为对照,测定青钱柳叶粗多糖的体外抗氧化能力。结果表明,青钱柳叶粗多糖清除DPPH自由基效果较好且较对照组浓度低,最高清除率为93.0%,而清除羟基自由基效果低于对照。     

超高压处理对黑莓汁有机酸、V_C及其协同抗氧化性的影响

采用反相高效液相色谱法、2,4-二硝基苯肼法对300～600 MPa处理15 min的黑莓汁中有机酸、VC进行检测分析,并采用DPPH.法对其协同抗氧化性进行评价。结果表明:黑莓汁有机酸主要是L-苹果酸,占总酸的87.98%,并含有少量的α-酮戊二酸、醋酸、柠檬酸和琥珀酸等;超高压处理对黑莓汁中琥珀酸和L-苹果酸的影响显著(P<0.05),对其他酸作用不显著(P>0.05)。经300 MPa、15 min处理,黑莓汁中L-苹果酸含量减少12.2%,400、500和600 MPa处理15min后,其L-苹果酸含量分别增加8.53%、6.08%和22.35%;超高压黑莓汁中VC的保留率在90.10%～97.92%;随着L-苹果酸浓度的增加,其协同VC清除DPPH自由基能力显著增强(P<0.05),表明L-苹果酸可协同VC增加其抗氧化性。     

Cloud Stabilization of Orange Juice by High Pressure Processing

High pressure processing (HPP) was investigated as a means to preserve cloud in freshly squeezed orange juice. Cloud loss is a major quality defect in orange juice, and methods of preserving cloud without the extreme temperatures used in commercial pasteurization are desirable. Pressures from 500 to 900 MPa were investigated at dwell times of 1 sec, 1 min and 10 min. Higher pressures and longer processing times were more effective at preserving cloud, while all treatments yielded a microbially stable product. A 90-day shelf life under refrigeration conditions could be achieved using pressures of 700 MPa and higher combined with treatment times of 1 min.     

储藏温度对荔枝果汁中酚类物质含量及抗氧化能力的影响

以经UHT杀菌的荔枝果汁为原料,分析5周内在4、25、37℃3个储藏温度下荔枝果汁中总酚含量、总黄酮含量及FRAP和ABTS抗氧化能力的变化。结果显示,随着储藏时间的延长,在4、25、37℃储藏温度下荔枝果汁中总酚含量与抗氧化能力均呈现显著下降趋势(p<0.05);总酚含量受储藏时间影响更显著(p<0.05),总黄酮含量受温度影响更显著(p<0.05),抗氧化能力则同时受储藏时间(p<0.05)和温度(p<0.05)的影响。由此表明不同储藏条件对荔枝果汁中酚类物质含量存在显著影响,低温及短时储藏有利于保持荔枝果汁中酚类物质含量及其抗氧化活性。     

果胶酶酶解库尔勒香梨果汁工艺条件优化

通过试验得出:香梨汁中果胶含量0.4%,最佳酶制剂为液态Pectinex BE XXL;并通过单因素对比试验初步确定库尔勒香梨果汁酶解的工艺条件,通过正交试验优化工艺参数,确定果胶酶酶解库尔勒香梨果汁的最佳工艺组合:酶制剂用量为120 mL/t,温度40℃,时间2 h,最适pH为5～5.5。     

混合清汁超滤过程中工艺条件的优化

超滤过程中操作条件的优化对于发挥超滤的优势是至关重要的,本文用ＨＰＭ型板框超滤器对亚法糖厂的混合清汁进行处理,研究超滤系统运行的最优工艺条件,通过测定聚蔗醚酮超滤膜的污染度和清洗效果确定了较可行的清洗方法。     

高压CO_2处理对西瓜汁的影响

以海南麒麟西瓜为原料,榨汁后进行HPCD(高压CO2)杀菌处理,处理温度为25℃,压力为20 MPa和30 MPa,处理时间分别为10、30和60 min,测定HPCD处理后西瓜汁的主要理化指标、细菌总数和PME酶(果胶甲基酯酶)活性变化。结果表明:HPCD处理后西瓜汁pH值降低0.3～0.7、可溶性固形物无明显变化、颜色更红、浊度增加,细菌总数降低可达到2个对数,果胶甲基酯酶活性可降低50%。     

Enzyme Activity and Nutritional Quality of Peach (Prunus persica) Juice: Effect of High Hydrostatic Pressure

The inactivation of polyphenol oxidase and pectin methylesterase in peach juice was investigated after high hydrostatic pressure processing at 400–600 MPa and 25°C for 5–25 min, respectively. At 400 MPa, polyphenol oxidase and pectin methylesterase were activated by 7.3 and 2.6%. At 500 and 600 MPa, polyphenol oxidase and pectin methylesterase were inactivated significantly with increasing the pressure and time, and the inactivation kinetics was fitted by the first order model. Moreover, some physio-chemical properties were studied. The results revealed that high hydrostatic pressure treatment preserved more L-ascorbic acid and maintained the color and sensory quality better than thermal treatment.     

Increase of Antioxidant Activity of Tomato Juice Upon Functionalisation with Vegetable Byproduct Extracts

Phenolic-enriched extracts from blanched artichoke (BA), artichoke blanching waters (ABW), cauliflower (CA), carrot (CR), celery (CE) and onion (ON) byproducts were used to ‘functionalise’ tomato juice. The antioxidant activity of functional tomato juice significantly increased over control juice according to a set of in vitro antioxidant assays (i.e. inhibition of lipid peroxidation determined by the ferric thiocyanate method and scavenging of both ABTS^•+ and DPPH^• free radicals). A trained sensory evaluation panel determined the maximal allowed byproduct extract concentration in the functionalisation of tomato juice without modifying its natural sensory properties (mg extract/mL tomato juice): 2.5, 5, 10, 10, 10 and 20 for CA, ON, BA, ABW, CE and CR, respectively. The maximum antioxidant activity (within consumers' acceptance limits and measured by the ABTS^•+ method) was increased 5.4-, 3.4-, 2.5-, 1.7-, 1.5- and 0.6-fold over the control when functional tomato juice was assayed after modification with ABW, BA, CR, ON, CE and CA, respectively. A serving of functional tomato juice (250 mL) containing vegetable extracts (within consumers' acceptance limits) provides an additional intake of phenolic compounds which can range from 22 mg (when functionalised with CA extract) to 300 mg (with BA extract). In the light of the above investigations, the use of vegetable byproducts could be useful for developing a functional tomato juice with potentially increased health-promoting properties.     

高D-α-生育酚抗氧化活性研究

对从实验室制备的高D-α-生育酚，用烘箱法及Rancimat法对其抗氧化活性和其他抗氧化剂进行了比较分析。结果表明，高D-α-生育酚对猪油有一定抗氧化性，高温时更明显；而对大豆色拉油及葵花籽色拉油有一定促氧化作用，高温时则不明显。     

海芦笋膳食纤维抗氧化性能的研究

通过测定海芦笋膳食纤维对自由基的清除能力,研究其抗氧化性能。采用羟基自由基体系、超氧阴离子自由基体系、烷基自由基引发的亚油酸氧化体系和DPPH体系对海芦笋膳食纤维清除自由基的活性进行研究。结果显示:海芦笋膳食纤维对羟基自由基的IC50为4.15 mg/mL;对超氧阴离子自由基,在本试验测定范围内的最高清除率为40.5%;对烷基自由基的IC50为3.6 mg/mL;对DPPH自由基的IC50为6.28 mg/mL。结论:海芦笋膳食纤维对羟基自由基、烷基自由基、DPPH自由基均有较强的清除能力,对于超氧阴离子自由基的清除能力较弱。但因为膳食纤维的纯度比阳性对照物低,清除机理也可能不尽相同,因此清除自由基的效果弱于阳性对照物。     

新疆哈密大枣汁浸提工艺及提取物抗氧化活性的研究

以哈密大枣为原料,以总糖、可溶性固形物含量为指标,通过正交试验确定哈密大枣汁的浸提工艺,并对哈密大枣提取物的抗氧化活性进行了研究.结果表明:当料液比为1∶11,浸提温度为70℃,浸提时间为60min时,在此条件下,浸提所得的枣汁中可溶性固形物含量为6.7%,总糖含量为12%;哈密大枣提取物有一定的清除DPPH的作用,与...     

冬枣汁与金丝小枣汁总酚、总黄酮含量及抗氧化性能的比较研究

研究比较了冬枣汁与金丝小枣汁对DPPH自由基清除率、ABTS+自由基清除率和金属螯合力。分别以成熟的沾化冬枣(Ziziphus jujuba Mill. cv. Dongzao var. Zhanhua)、乐陵金丝小枣(Ziziphus jujuba)和去离子水按照2∶1打浆,经酶解、离心、过滤得到枣汁。测定冬枣汁与金丝小枣汁不同添加量的DPPH自由基清除率、ABTS+自由基清除率、金属螯合力和还原能力。结果表明:冬枣汁总酚、总黄酮含量均远高于金丝小枣样品;冬枣汁和金丝小枣汁都具有一定的抗氧化性能,且均高于Vc对照样。两者相比,冬枣汁对DPPH自由基、ABTS+自由基具有较高清除能力,并且具有较强的金属螯合能力和还原能力。