Effects of juice processing on cranberry antioxidant properties

The effects of the industrial juice process on the antioxidant capacities of cranberry samples and of three phenolic extracts (polar phenolics (E1), apolar phenolics (E2) and anthocyanins (E3)) adjusted at pH 2.5 and 7.0 were investigated. The free radical-scavenging (FRS) and the lipid peroxidation inhibition (LPI) activities of each sample and extract, were studied using a N,N-diethyl-p-phenylenediamine discoloration test and the thiobarbituric acid reactive substances assay, respectively. The FRS and the LPI results, expressed in mM Trolox® equivalent (TE)/mg phenol and mg TE/mL/mg phenol, respectively, showed a negative effect of the juice process steps on E1. The E2 and E3 extracts were also affected by the process but not as much. The milling step increased the FRS capacity of E2 and E3 extracts, but decreased their LPI capacity. The evaporation of the juice did not have a significant effect on the FRS capacity, but lowered the LPI capacity. Before and after each step of the juice process, the FRS capacity of the cranberry extracts was greater than the LPI capacity. The results were consistent in classifying the FRS capacity of the extracts in the following order of polarity: E1 > E3 > E2; and their total phenolic (TP) content in the following order: E3 > E2 > E1. In general, the neutralization of the pH of the extracts did not significantly influence the changes observed during the juice process in the FRS and LPI capacity, except for E3 for which a decrease in the LPI capacity was observed.     

Effect of juice processing on the cancer chemopreventive effect of cranberry

Cancer chemopreventive properties were evaluated in cranberries and cranberry products (mash, depectinized mash, pomace, raw juice, clarified juice and juice concentrate). Three extracts isolated from frozen cranberries and cranberry solids (mash, depectinized mash and pomace) containing anthocyanins, water-soluble and apolar phenolic compounds were tested. Cranberry juices and extracts were screened for their ability to induce the phase II xenobiotic detoxification enzyme quinone reductase (QR). The results showed that there was no cytotoxicity against the cells used in the test. All samples stimulated quinone reductase activity except the highest concentrations of the anthocyanin-rich extract of pomace, which inhibited QR activity. Also, the results showed that the QR induction for all samples varied with concentration and that there was an optimal concentration for which the QR induction was maximal. Although the three cranberry extracts were good QR inducers, our results indicated that the phenols present in aqueous extract showed QR inductions which were more important than those obtained with phenols present in solvent extracts. Also, the ability of phenols to stimulate the QR activity has been reduced continuously and significantly (P ≤ 0.05) during the technological process. Especially, it appears that conditions of the evaporation to obtain a juice concentrate exerted a significant effect (P ≤ 0.05) on inducer potencies of bioactive molecules.     

Antioxidant and antiradical properties of cranberry juice and extracts

The antioxidant capacities of cranberry juice and three extracts isolated from frozen cranberries containing anthocyanins, water-soluble and apolar phenolic compounds, were evaluated at pH 2.5 and 7, respectively. The free radical-scavenging (FRS) and the lipid peroxidation inhibition (LPI) activities of each samples, and extracts, were studied using the N,N-diethyl-p-phenylenediamine (DPD) decoloration test and the thiobarbituric acid reactive substances (TBARS) assay, respectively. The cranberry phenols displayed good free radical-scavenging properties, but were less efficient at inhibiting the peroxidation of lipids. Of all the samples tested, the water-soluble phenolic compounds showed the greatest free radical-scavenging (68.2 mmol TE/mg phenol) and antioxidant (13.4 mmol TE phenol) activities. The polarity of the phenols, the pH of the medium and the juice process had a great influence on the antioxidant activities. The phenols isolated from cranberries with an aqueous solvent have greater antioxidant properties than those extracted with an organic solvent mixture. The antioxidant activity of the cranberry samples adjusted at pH 2.5 was greater than those adjusted at pH 7. Compared to the cranberry extracts, the juice exhibited a much lower antioxidant activity, especially when compared with the extract containing water-soluble compounds which the extraction conditions were similar to those used to obtain the juice.     

Effect of different cranberry extracts and juices during cranberry juice processing on the antiproliferative activity against two colon cancer cell lines

The effect of cranberry extracts and juices during cranberry juice processing on the antiproliferative properties against colon cancer cells was investigated. Two colon cancer cell lines HT-29 and LS-513 were treated with different concentrations of cranberry phenolic extracts from fruits, puree, depectinised puree and pomace and different concentration of three juices (raw, filtered and concentrated juices). The phenolic extracts consisted of water-soluble phenolic compounds, apolar phenolic compounds and anthocyanins. These phenolic extracts and juices were tested against two cell lines at pH 2.5 (natural juice pH) and at pH 7.0 (physiological pH). All cranberry extracts and juices could inhibit the growth of both cell lines with the IC₅₀ values (the concentration of phenolic content required to inhibit 50% the growth of cancer cells) varied from 3.8 to 179.2 μg gallic acid equivalent/ml. It was found that three types of extracts from fruit at pH 7.0 were the most effective at inhibiting the growth of HT-29 cell line. Extracts containing anthocyanins from fruit and from pomace were the most and the least efficient, respectively, in inhibiting the growth of both cancer cell lines. Further, three juices at natural pH (pH 2.5) were more effective at inhibiting the growth of two cell lines as compared to juices at pH 7.0. Concentrated juice at both pH values was the most effective at growth inhibition of two cancer cell lines compared to two other juices.     

Impact of selected combinations of non-thermal processing technologies on the quality of an apple and cranberry juice blend

A blend of apple and cranberry juice was processed by a combination of a light-based technology (ultraviolet light (UV) (5.3 J/cm²) or high intensity light pulses (HILP) (3.3 J/cm²) in combination with pulsed electric fields (PEF) (34 kV/cm, 18 Hz, 93 μs) or manothermosonication (MTS) (5 bar, 43 °C, 750 W, 20 kHz). Selected physical and chemical attributes were evaluated pre- and post-processing, and the sensory attributes of non-thermally treated samples were compared to conventional pasteurisation (26 s, 72 °C). No significant changes were found in non-enzymatic browning, total phenolics and antioxidant activity of the juices. UV + PEF and HILP + PEF treatments did not affect the colour of the product and HILP + PEF processing retained more monomeric anthocyanins than any other combined treatment. Sensory analysis showed that UV + PEF and HILP + PEF combinations did not impact on odour and flavour of the juice, while combinations that included MTS adversely affected those attributes.     

蜜环菌抑菌作用的初步研究

采用滤纸片法、液体培养法和活菌计数法,研究了蜜环菌菌索提取液对常见微生物的抑制作用。通过测定MIC值,蜜环菌的抑菌能力依次为:大肠杆菌>金黄色葡萄球菌>枯草芽孢杆菌>啤酒酵母菌。15%的蜜环菌浸提液可抑制细菌生长,高于20%的蜜环菌浸提液可对霉菌和酵母菌产生抑制作用。     

连翘不同部位提取物抑菌效果的比较分析

本试验采用滤纸片扩散法测定了连翘的花、叶片、枝条、果实(分青翘和老翘)的乙醇提取物对三种细菌性病害大肠杆菌(Escherichia coli)、金黄色葡萄球菌(Staphylococcus aureus)、枯草芽孢杆菌(Bacillus subtilis)和3种真菌病害青霉菌(Penicillium)、葡萄灰霉菌(Botrytis cinerea)和黄曲霉(Aspergillus flavus)进行了抑菌效果的对比和分析。用液体悬浮培养法分别测定了连翘不同部位的乙醇提取物对3种细菌的最小抑菌浓度(MIC)。试验结果表明:连翘不同部位的乙醇提取物对供试细菌均表现出有较强的抑菌作用,其中果实中青翘提取物的抑菌作用最强、老翘和叶片的抑菌作用也比较强,且两者区别不大,枝条提取物的抑菌作用最弱;对3种供试真菌所有供试部位提取物的抑菌效果均比细菌差。不同部位的乙醇提取物对不同细菌的最小抑菌浓度(MIC)则表现较大差异。     

鲍鱼壳煅烧物抗菌活性初步研究

研究鲍鱼壳煅烧物对几种常见致病菌的体外抗菌活性。采用滤纸片法和牛津杯双层琼脂扩散法测试不同温度段鲍鱼壳煅烧物对受试菌的抑制作用,并用琼脂梯度稀释法确定最小抑菌浓度(MIC)。结果表明:当煅烧温度段≥800℃,鲍鱼壳煅烧物对几种常见致病菌均有较强的抑制作用,尤其对金黄色葡萄球菌和铜绿假单鲍菌具有显著的抑制作用(p<0.05),MIC分别为1 mg/m L和0.5 mg/m L;并且在一定温度范围内,其对受试菌的抑制能力均随煅烧温度的升高而显著增加,在1100℃煅烧温度上抗菌效果最好。      

超高压加工对鲜榨胡萝卜汁品质的影响

重点研究了热敏性胡萝卜汁经200～600MPa超高压处理10min后其感官品质、理化性质及营养品质的变化情况。实验结果表明:经高压处理后胡萝卜汁色泽、可溶性固形物、总糖、α-和β-胡萝卜素含量与对照样相比差异不明显(P>0.05);总抗氧化能力在400MPa压力处理后降低较显著,600MPa处理有较显著的提高(P<0.05);此外,超高压处理后胡萝卜汁的pH降低,总酸含量增加,且样品的沉降稳定性提高,且变化都比较显著(P<0.05)。综合实验各方面的处理效果,600MPa处理后的胡萝卜汁品质最佳。因此,超高压能较好保持胡萝卜汁原有的品质和营养价值,可达到保持营养、提高品质和延长货架期的目的。     

超高压处理对蓝莓汁品质的影响

以蓝莓汁为原料,采用200～500MPa高压分别对蓝莓汁处理5～15min,对处理后的蓝莓汁进行微生物和理化指标检测。研究结果表明:超高压处理杀菌效果显著,400MPa处理10min已无菌落检出;高压处理对蓝莓汁色泽、还原糖、可溶性固形物的影响较小,蓝莓汁中的花青素和VC含量在高压处理后保留率达90%以上,而总酸和总酚含量略有下降。      

Antimicrobial effects of selected plant essential oils on the growth of a Pseudomonas putida strain isolated from meat

The inhibitory effect of 60 different essential oils was evaluated on a Pseudomonas putida strain of meat origin, associated with meat spoilage. Essential oils were tested at concentrations from 0.003 to 0.8% (wt/vol) to determine minimum inhibitory and maximal tolerated concentrations (MIC and MTC, respectively) using an agar medium culture. Of the 60 samples tested, Corydothymus capitatus essential oil was the most active showing a MIC of 0.025% and a MTC of 0.06%. Seven essential oils (Cinnamomum cassia, Origanum compactum, Origanum heracleoticum, Satureja hortensis, Satureja montana, Thymus vulgaris carvacroliferum, Thymus vulgaris thymoliferum) have shown a strong antimicrobial activity against P. putida with a MIC of 0.05% and a MTC ranging from 0.013% to 0.025%. Ten other oils (Cinnamomum verum (leaf and bark), Eugenia caryophyllus, Cymbopogon martinii var. motia, Cymbopogon nardus, Melaleuca linariifolia, Origanum majorana, Pimenta dioica, Thymus satureoides, Thymus serpyllum) showed a high antimicrobial activity showing a MIC ranging from 0.1% to 0.4%, while the remaining were less active showing a MIC ? 0.8%.     

大蒜油抗菌作用的初步研究

就大蒜油对一些常见的污染食品的微生物进行了抑制与杀灭作用的研究。结果表明，大蒜油对供试微生物具有很强的抑制与杀灭作用。     

黄芪提取物抗菌作用及其方式的研究

研究了不同产地黄芪提取物对食品中常见的腐败菌和产毒菌的抗菌作用与方式。结果表明：黄芪醇提物比水提物的抗菌效果明显,来自内蒙古和甘肃黄芪提取物抗菌作用没有明显的差异,黄芪醇提取物的抗菌作用因菌种不同而有所不同。同时,黄芪提取物的抗菌作用方式为杀菌,且其抗菌作用与时间有关。     

生姜澄清汁加工工艺研究

姜营养物质丰富,对人体健康极其有益。实验采用单宁、明胶、壳聚糖处理法对姜汁进行处理,通过测定姜汁的透光率及澄清后的姜汁热稳定性确定3种方法对姜汁澄清效果。结果表明:明胶添加量0.04‰,单宁添加量0.07‰,常温下静置1 h,此时姜汁的透光率可达到98.6%;壳聚糖添加量0.4‰,作用温度40℃,作用时间40 min,透光率为96.8%。经过壳聚糖-硅藻土结合法处理姜汁,透光率达99.2%。     

抗氧化剂对大枣汁加工中VC的影响

大枣汁加工过程中VC的保存是影响大枣产品质量的关键技术。通过不同抗氧化剂处理试验,表明植酸处理对还原型VC的保存效果最好,其次是0.04%的六偏磷酸钠和0.06%的Na2EDTA;茶多酚和Na2EDTA对氧化型VC的降解起抑制作用,六偏磷酸钠可使氧化型VC的含量增高。     

苦瓜总皂甙最小抑菌浓度和最佳抑菌条件的研究

苦瓜总皂甙是苦瓜中有效成分,具有抑菌等作用。通过绘制生长曲线判断苦瓜总皂甙对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌和黑曲霉菌生长曲线的影响。采用琼脂稀释法测定苦瓜总皂甙的最小抑菌浓度(MIC)。运用正交实验设计法确定苦瓜总皂甙的最佳抑菌条件。结果表明,苦瓜总皂甙对黑曲霉菌的生长几乎没有抑菌作用。浓度为50、100、150、200mg/mL的苦瓜总皂甙对大肠杆菌、枯草芽孢杆菌、金黄色葡萄球菌生长均有抑制作用,且以150mg/mL浓度时为最强,MIC分别为30、40、30mg/mL。苦瓜总皂甙对大肠杆菌和金黄色葡萄球菌的最佳抑菌条件为:40℃下,pH为6.0时,抑菌20h。      

菠萝蜜果汁加工工艺的研究

以成熟的菠萝蜜果实为原料,采用单因素和正交试验,研究了澄清型菠萝蜜果汁的酶解工艺条件及调配方法。结果表明:用果胶酶酶解菠萝蜜果汁有明显的澄清效果,酶解菠萝蜜果汁的优化工艺条件为酶解温度50℃、酶解时间2.5h、果胶酶用量0.1%;酶解后的菠萝蜜果汁的最佳配方为糖度20°Bx、柠檬酸0.1%、抗坏血酸0.06%。     

蕺菜汁饮料生产工艺研究

对蕺菜汁饮料生产工艺作了研究。结果表明,以蕺菜地上茎或地下茎叶为原料,经１００℃烫漂１ｍｉｎ后破碎、榨汁,再用复合果胶酶澄清处理,最后经调配、精滤、灌装和灭菌等过程可制成风味独特的蕺菜汁饮料。添加少量的食盐有利于保持和改善蕺菜汁饮料的风味     

鱿鱼鱼精蛋白的抑菌作用及在保鲜中的应用

以鱿鱼精巢组织为原料,从中分离提取鱼精蛋白。确定其对大肠杆菌、金黄色葡萄球菌的最低抑菌浓度(MIC)后,将其添加到新鲜的鱼糜制品中,研究了pH值、无机成分、有机成分和其他化学物质对鱼精蛋白抑菌活性的影响。结果表明,鱼精蛋白是一种有效的天然食品防腐剂。     

黄芪提取物对细菌抑制作用的研究

本文以黄芪作为研究对象,利用制得的黄芪提取物对多种细菌进行了抑菌活性实验,结果表明:黄芪提取物抑菌作用因菌种不同而最低抑菌浓度有所不同,大肠杆菌为7.5%、产气杆菌为8%、变形杆菌为4.5%、金黄色葡萄球菌为9.5%、沙门氏菌10%,其抑菌直径分别为:大肠杆菌8.6mm、产气杆菌8.1mm、变形杆菌8.2mm、金黄色葡萄球菌7.7mm、沙门氏菌8.4mm,表明对常见细菌有较好的抑制作用,其抑菌效果与时间有一定关系,在121℃湿热条件下20min后黄芪提取物抑菌效果基本不变,说明制得的黄芪提取物具有良好的热稳定性。此外,黄芪提取物抑菌浓度与时间有关。