柠檬汁对甘蔗汁保鲜工艺的研究

为了研究甘蔗汁的保鲜工艺。利用单因素法考查了加热温度、加热时间和柠檬汁与甘蔗汁体积比对甘蔗汁保鲜的影响,在此基础上利用L9(34)正交试验考查了甘蔗的3、6、9 d的保鲜效果。结果表明适当的增加加热温度、延长加热时间和增加柠檬与鲜甘蔗汁的体积比能够有效延长甘蔗汁的保鲜时间。甘蔗汁贮藏6 d的最优组合为A3B3C2,即处理温度为140℃,处理时间为45 min,柠檬汁与甘蔗汁体积比为4∶40;因素的主次关系为:处理温度(A)、处理时间(B)、柠檬汁与甘蔗汁体积比(C)。鲜甘蔗汁在加入柠檬汁与甘蔗汁体积比为4∶40,120℃温度下加热25 min时,甘蔗汁可有效保鲜9 d。     

柠檬和甘蔗汁混合发酵酿酒工艺研究

本实验研究了柠檬汁和甘蔗汁混合发酵酿酒的加工工艺.首先对糖度、pH值、温度和接种量等对主发酵的影响作了单因素实验,初步确定4个因素对主发酵影响程度的主次顺序:糖度＞pH值＞温度＞接种量,并且确定了每个因素的最适范围.最后,采用正交优化法筛选出最佳的发酵工艺参数组合.结果表明,最佳发酵工艺条件为糖度22%、pH 3.6、温度17℃、接种量6%.     

NFC柠檬汁生产与柠檬综合利用技术研究

以提高柠檬果利用率为目的,研究开发同时生产柠檬精油、NFC柠檬汁和柠檬条糖制品生产技术,结果表明,出汁率40.3%的适度榨汁可以获得高感官品质的NFC柠檬汁和柠檬条糖制品以及每吨柠檬鲜果生产3.1 kg冷磨柠檬精油,达到良好的综合经济效益。     

Lemon Juice Aroma Concentration by Reverse Osmosis

Ethanol, a major component of lemon juice, was analyzed to indicate degree of lemon juice aroma concentration. Aroma solution was concentrated from 12.2 to 23.4% ethanol at 8.3 MPa and 19°C by reverse osmosis. Ethanol rejected by the membrane decreased from the initial 87.7% to 78% at the final aroma concentration of 23.4% ethanol. Membrane rejection of neral, geranial, and terpinene-4-ol was > 96% while rejection of the alcohols, n-propanol, 2-methyl-3-buten-2-ol, and 3-methyl-2-buten-1-ol, ranged from 6.9% to 83.5%. Sensory analysis indicated no difference between initial aroma and aroma concentrated by reverse osmosis. Mass balance determined the true recovery of total volatiles was 79.7%. Loss of volatiles was attributed to adsorption in the polymeric matrix of the membrane and some loss was attributed to cleaning.     

Lemon Juice Color Evaluation: Sensory and Instrumental Studies

The ability to use the Hunter Citrus Colorimeter D45 for the objective measurement of lemon juice color was studied. The correlation coefficient between 25 panelists’visual ranking of lemon juice lightness to darkness and the calorimeter D45 color scores was 0.98. This paper presents the methods used in preparing the lemon juice sample for color measurement and the implication of the sensory results for the potential use of the Hunter Citrus Colorimeter D45 for lemon juice color measurement by the citrus industry.     

活性硅酸镁对柑桔汁中柠檬苦素吸附的研究

研究了活性硅酸镁吸附橙汁和柠檬汁中的柠檬苦素。实验表明,而在只加入1．5％和2％的650℃活化的硅酸镁,当摇床频率为150r／min、振荡温度为10℃、振荡1．5h经7000r／min高速离心5min,可将柠檬苦素的脱除率达到97％以上,且对其品质影响较小。     

Aroma of Canned Peach Halves Acidified with Clarified Lemon Juice

The aroma composition of canned peaches was studied during the 1st year of storage. Citric acid was substituted with 2 types of lemon juice: turbid and clarified. The volatiles were extracted using a distillation technique and quantified by gas chromatography‐mass spectrometry. A total of 35 aroma compounds were identified and quantified, with the major volatile components being lactones. The removal of monoterpenes, during the tangential flow filtration of the lemon juice, provided an acidifier with high scores in the sensory evaluation. In this study, a product perceived by the consumers as more “natural” was elaborated, and new industrial perspectives were opened for the lemon industry and agriculture.     

基于高通量测序分析不同品种柠檬NFC果汁的微生物多样性

目的:探索柠檬非浓缩还原汁(Not From Concentrate,NFC)中微生物多样性,为柠檬NFC灭菌工艺优化提供理论数据.方法:采集不同品种柠檬NFC,利用HiSeq高通量测序技术,比较不同柠檬NFC样品中细菌和真菌多样性差异.结果:通过高通量测序共获得147231条有效16S rDNA序列和113238条有...     

柠檬汁中游离态和键合态萜类化合物的研究

应用Amber lite XAD-2柱吸附,选用不同的溶剂洗脱从柠檬汁中提取和分离出游离态和糖苷键合态的香气组分。键合态组分经β-D-葡萄糖苷酶水解释放出挥发性糖苷配基。用气相色谱和质谱联用仪在游离态和键合态中分别检出了16种和9种萜类化合物,其中有5种为首次在柠檬香气中发现。酶法水解对柠檬香气有明显的增香作用。HPLC分析苷元可能是葡萄糖和鼠李糖。     

柠檬汁和甘蔗汁混合发酵酿酒酵母的筛选

通过发酵实验从7株酵母菌中筛选出发酵J}生能较好的3株菌株（7^#，1^#，6^#），并对3株酵母菌进行抗硫性、抗酸性、耐糖、耐酒精性能和耐温性能试验，最后筛选出发酵性能优良的7^#和6^#酵母菌株。其产酒率高，具有较好的耐二氧化硫能力（80～120mg／L）；能在pH3．3～3．5，糖浓度24％～27％，酒精度12％Vol～14％Vol的范围内生长和发酵；发酵结束残糖含量低，凝聚能力好；发酵所得原酒品质好，酒的风味醇和，果香、酒香浓郁、协调；7^#和6^#两株菌可应用于柠檬、甘蔗混合发酵产酒。（孙悟）     

柠檬汁纳米银抗菌复合膜的制备工艺优化及性能研究

本研究以聚乙烯醇(PVA)和可溶性淀粉(SS)为原料,甘油为增塑剂,柠檬汁(LJ)为还原剂将硝酸银原位还原成纳米银(AgNPs),制得抑菌性能良好的PVA-SS-LJ-AgNPs复合膜.经单因素及正交试验得出,最佳制膜工艺为PVA 3 g、SS 0.5 g、甘油3 g、LJ 7 mL、硝酸银130 mmol/L,最优工...     

2种浓缩方法对柠檬汁特性影响的比较

采用界面渐进冷冻浓缩法和真空蒸发法分别对柠檬汁进行界面渐进冷冻浓缩和真空蒸发浓缩。通过对 2种浓缩液处理前后柠檬汁香气成分含量的定性定量分析 ,以及柠檬汁色差、Vc含量、电导和 pH值的比较分析 ,证明了冷冻浓缩柠檬汁明显地比真空蒸发浓缩果汁能更好地保持柠檬汁的香气成分、Vc含量和原汁的香气协调性。     

不同预处理方式对柠檬果汁超滤澄清效果和膜污染情况的影响

利用超声辅助果胶酶法和超滤技术相结合对柠檬果汁进行澄清。以柠檬汁的透光率、果胶含量为指标,讨论不同预处理方式对柠檬果汁超滤澄清效果和膜污染情况的影响。结果表明,采用切割分子量为50 kDa的聚丙烯腈(PAN)超滤膜澄清果汁,不同预处理方式对超滤膜的稳定通量大小的影响规律是酶+超声处理>酶处理>未经酶+超声处理,其稳定通量分别为30、33.5和13 L·m-2·h-1左右。较优的操作压力可确定为0.1 MPa,此时柠檬汁的果胶含量为0.5%,透光率约99.6%,处理效果较好。超声辅助果胶酶法澄清果汁,有利于提高果汁的透光率,并且在后续膜处理过程中,对于提高超滤膜的通量和缓解膜污染都有显著的效果。     

Pectin Extraction from Lemon By-Product with Acidified Date Juice: Effect of Extraction Conditions on Chemical Composition of Pectins

Mixtures of date and lemon pectins were extracted from lemon by-product with acidified date juice under different conditions of temperature, pH and time. Individual pectins from date and lemon, respectively, were also extracted using the same experimental conditions, then analysed and compared to pectin mixtures. It was found that the use of extreme conditions resulted in higher galacturonic acid content, lower degree of methylation, lower neutral sugar content, lower molecular weight and darker colour pectins. Examination of the individual neutral sugars showed that the main ones were galactose (1.6–5.4%), arabinose (1.6–4.2%) and rhamnose (0.5–0.8%). The Gal A/Rha molar ratios varied from ∼53 to ∼149. Moreover, mixture of pectin extracted at the optimal extraction conditions (84.34 °C, pH 2.8 during 3 h 34 min) had interesting properties, with a high galacturonic acid content (63.4%), low degree of methylation (∼35%) and a mass molecular weight of about 243 kg/mol.     

Inhibition of Clostridium perfringens Spore Germination and Outgrowth by Lemon Juice and Vinegar Product in Reduced NaCl Roast Beef

Abstract: Inhibition of Clostridium perfringens spore germination and outgrowth in reduced sodium roast beef by a blend of buffered lemon juice concentrate and vinegar (MoStatin LV1) during abusive exponential cooling was evaluated. Roast beef containing salt (NaCl; 1%, 1.5%, or 2%, w/w), blend of sodium pyro‐ and poly‐phosphates (0.3%), and MoStatin LV1 (0%, 2%, or 2.5%) was inoculated with a 3‐strain C. perfringens spore cocktail to achieve final spore population of 2.5 to 3.0 log CFU/g. The inoculated products were heat treated and cooled exponentially from 54.4 to 4.4 °C within 6.5, 9, 12, 15, 18, or 21 h. Cooling of roast beef (2.0% NaCl) within 6.5 and 9 h resulted in <1.0 log CFU/g increase in C. perfringens spore germination and outgrowth, whereas reducing the salt concentration to 1.5% and 1.0% resulted in >1.0 log CFU/g increase for cooling times longer than 9 h (1.1 and 2.2 log CFU/g, respectively). Incorporation of MoStatin LV1 into the roast beef formulation minimized the C. perfringens spore germination and outgrowth to <1.0 log CFU/g, regardless of the salt concentration and the cooling time. Practical Application: Cooked, ready‐to‐eat meat products should be cooled rapidly to reduce the risk of Clostridium perfringens spore germination and outgrowth. Meat processors are reducing the sodium chloride content of the processed meats as a consequence of the dietary recommendations. Sodium chloride reduces the risk of C. perfringens spore germination and outgrowth in meat products. Antimicrobials that contribute minimally to the sodium content of the product should be incorporated into processed meats to assure food safety. Buffered lemon juice and vinegar can be incorporated into meat product formulations to reduce the risk of C. perfringens spore germination and outgrowth during abusive cooling.     

Effect of Initial Dissolved Oxygen Levels on the Degradation of Ascorbic Acid and the Browning of Lemon Juice during Storage

The effect of different initial dissolved oxygen concentrations (0.41, 1.44, and 3.74 mg/L) on rate of deteriorative quality changes [ascorbic acid degradation, browning, hydroxymethylfurfural (HMF) and furfural production) in lemon juice stored at 36°C was investigated. No significant effects on rate of ascorbic acid degradation and furfural formation could be attributed to the different oxygen levels. Degradation of ascorbic acid appeared to be predominantly anaerobic. Lag period before browning increased depended on oxygen level. Zero-, first- and second-order kinetic models were fitted to various degradative reactions occurring in lemon juice during storage. Highly significant correlations were obtained between browning index, HMF, and furfural formation, suggesting that all three would be suitable as chemical indices of storage temperature abuse in lemon juices.