电子鼻对低温贮藏猕猴桃品质的预测

为了探索电子鼻技术快速检测猕猴桃品质的方法,以“秦美”猕猴桃为试材,利用电子鼻技术对低温贮藏猕猴桃的芳香成分进行检测,采用多元线性回归（multiple linear regression,MLR）、偏最小二乘法（partial leastsquaresregressions,PLS）、BP（back-propagation）网络3 种分析方法建立评价低温贮藏期猕猴桃的可溶性固形物含量、pH值和硬度的数学模型。结果表明：在贮藏0～45 d,S1、S2、S3、S4、S7、S8、S9和S10传感器响应值变化显著（P＜0.05）,即芳香苯类、氮氧化物、氨类、氢气、硫化氢、乙醇、有机硫化物、芳香烷烃这几类化合物在猕猴桃低温贮藏期变化显著。同时线性判别分析比主成分分析能更好地区分不同贮藏期的猕猴桃。MLR、PLS和BP网络3 种分析方法都能很好地预测低温贮藏猕猴桃的品质,但相比之下,BP网络的分析精度更高。应用电子鼻技术预测猕猴桃的品质是可行的。     

Overall Quality Properties of Kiwifruit Treated by Cinnamaldehyde and Citral: Microbial,Antioxidant Capacity during Cold Storage

This work was undertaken to evaluate the microbiological characteristics and antioxidant and physiological activities in kiwifruits (Actinida deliciosa var. Qinmei) with/without cinnamaldehyde (C1) and citral (C2) fumigation treatments (5 μL/L) during 0, 3, 6, 9, and 12 d of storage at 4 °C. Essential oils (EOs) treatment lowered the total viable counts, yeast, and mold to 1.54, 2.36, and 2.05 log CFU/g, respectively. Moreover, EOs improved the antioxidant activities of kiwifruit. They enhanced phenolics and flavonoids content in fruit tissue by 49.48% at day 3 and 56.93% at day 6, respectively. In addition, ascorbic acid in treated groups had the lower losing rate. Similarly, MDA (malondialdehyde), H₂O₂ (hydrogen peroxide), and ^?O₂^– (superoxide anion) production were effectively decreased in the range of 27.27% to 54.38%. Physicochemical characteristics showed that kiwifruits from treated group maintained higher levels of flesh luminosity and firmness. EOs also decreased the levels of reducing sugar by 45.97% at day 3, and increased the content of soluble protein and hydrolyzed amino acid. Therefore, postharvest EOs treatment has positive effects on delaying senescence and enhancing antioxidant capacities in kiwifruit.     

发酵芹菜粉对风干肠冷藏过程中理化特性的影响

利用发酵芹菜粉(Fermented Celery Powder,FCP)替代亚硝酸盐生产风干肠。将3种发酵芹菜粉(FCP506、FCP504、FCPmlz)分别替代亚硝酸盐,同时以添加亚硝酸盐(0.1 g/kg)为阳性对照组(PC),不添加亚硝酸盐为阴性对照组(NC)生产风干肠,探究风干肠成熟后,经过真空包装,在4℃的条件下贮藏4周,FCP对其理化特性的影响。研究结果表明:冷藏期间,5组风干肠的p H、Aw和水分含量变化差异不显著;NC组的TBARS值、TVB-N值明显高于其他4组(P0.05),NC组的亚硝酸盐残留量、a*值明显低于其他4组(P0.05),而PC、FCP506、FCP504和FCPmlz4组之间差异不显著。说明FCP应用于风干肠可以替代亚硝酸盐的发色、抗氧化等作用,为生产天然肉制品奠定了理论基础。     

Changes in Physicochemical Properties of Rice during Storage

The changes in the physicochemical properties of rices which had different amylose contents were studied when the rice was stored at 2°C and 29°C as rough rice, milled rice, defatted milled rice, and as starch. Changes in hardness index, water absorption, stickiness, viscosity, salt-soluble protein, free fatty acids, and carbonyl compounds during storage are discussed.     

不同品种红树莓籽油理化性质及脂肪酸组成比较

本实验以东北地区宝石红、秋福、哈瑞太兹、菲尔杜德、欧洲红5种红树莓籽为原料,采用超声波辅助提取红树莓籽油,对不同品种的红树莓籽油进行了理化指标测定,并经气相色谱质谱联用法分析红树莓籽油的脂肪酸组成,同时进行了欧洲红红树莓籽油的稳定性研究。实验结果表明,5种红树莓籽油酸值2.13~8.54 mg/g、皂化值125~168 mg/g、过氧化值0.27~2.72 mmol/kg、碘值123~148 g/100 g,属干性油;5种红树莓籽油脂肪酸组成以不饱和脂肪酸为主,其中主要为亚油酸(45.38%~51.06%)、α-亚麻酸(26.42%~32.31%)和油酸(10.09%~14.00%);欧洲红红树莓籽油稳定性受光照、氧气、温度和抗氧化剂影响,其中温度和氧气是主要影响因素,高温加氧气会极大地促进红树莓籽油的氧化;(63±1)℃下21 d后红树莓籽油氧化程度是常温组的7.21倍;常温下21 d后有氧组红树莓籽油氧化程度是无氧组的6.20倍;光照条件下21 d后的氧化程度是避光组的2.12倍。抗氧化剂能一定程度地延缓其氧化进程,3种人工合成抗氧化剂之间效果差异不显著,α-生育酚效果不如人工合成抗氧化剂。     

外源精胺对哈密大枣冷藏期间贮藏特性的影响

为了研究多胺处理对枣果实采后冷藏期间贮藏特性的影响,探讨保持鲜枣果实品质的方法。以绿熟期哈密大枣为试材,用浓度分别为1×10-4、1×10-5、1×10-6mol/L的精胺溶液室温处理鲜枣果实24h,并在(0±0.5)℃冷库中贮藏30 d。研究表明:精胺处理可有效延缓鲜枣果实硬度下降,维持果实中可溶性固形物、可滴定酸以及VC的含量,抑制鲜枣果实的呼吸作用和多酚氧化酶(PPO)的活性,减少果实的腐烂率。由此表明,浓度为1×10-4 mol/L精胺处理能显著延缓鲜枣果实的衰老,提高果实的冷藏期间的贮藏品质。     

海参低温贮藏过程中品质与理化性质的变化

研究预处理的海参在4℃条件下贮藏60 d的品质及理化性质变化.定期分析处理组和对照组海参可溶性胶原蛋白含量、硬度和咀嚼度变化,蛋白质降解情况,组织蛋白酶-L的活性,Caspase-3的活性,结构蛋白表达量的变化及自由基的生成情况.结果表明,随着低温处理时间的延长,前期各指标变化不显著,可溶性胶原蛋白含量从第10天开始明...     

大鲵肉冷藏过程中理化指标及挥发性成分的变化

为探讨大鲵肉冷藏期间理化指标及挥发性成分的变化,对冷藏过程（4 ℃,0~8 d）中大鲵肉定期进行感官评价、挥发性盐基氮（total volatile basic nitrogen,TVB-N）值和菌落总数测定,并采用顶空固相微萃取结合气相色谱-质谱联用技术（headspace solid phase microextraction combined with gas chromatography-mass spectrometry,HS-SPME-GC-MS）分析大鲵肉挥发性成分的变化。结果表明,随着冷藏时间的延长,大鲵肉感官品质逐渐下降,而TVB-N值和菌落数呈上升趋势。其中,大鲵肉在第5 d感官上不可接受,TVB-N值在第7 d超过可接受上限（30 mg/100 g）,菌落总数在第6 d超过可接受上限(6 lg CFU/g)。不同冷藏时间大鲵肉共检测出7类58种挥发性物质,其中,醇类（14种）、酯类（12种）相对含量较高。随着冷藏时间的延长醇类含量呈下降趋势,而酯类含量呈增加趋势,其他类化合物在冷藏过程中呈波动趋势。聚类分析将不同冷藏时间大鲵肉聚为4类,即前4 d、第5 d、第6 d和第7 d、第8 d。相关性分析表明,己酸己酯、2-甲基丁酸乙酯、2-庚酮、2,3-丁二酮、芳樟醇可作为大鲵肉冷藏期间腐败变质的潜在标记物。该研究为大鲵肉冷藏期间新鲜度评价及其品质控制提供了参考。     

UHT-Sterilized Peanut Beverages: Changes in Physicochemical Properties during Storage

Strawberry-flavored and chocolate-flavored peanut beverages were produced in a pilot plant, UHT sterilized at 137°C for 4 sec and 20 sec, aseptically filled and stored at 5, 20 or 35°C. Microbiological and physicochemical properties of the beverages were periodically assessed for up to 6 mos. No Microbial growth was observed. The pH decreased while homogenization and sedimentation indices increased with time in all beverages at all temperatures. Color lightness decreased during the first 6 wk and remained constant afterwards. Viscosity of strawberry-flavored beverage was constant whereas chocolate-flavored beverages gelled after 19 wk at all temperatures. Proteolysis was <6% in gelled beverages.     

不同冷藏时间牦牛乳中细菌群落结构和理化性质比较

低温贮藏有利于确保原料乳质量,然而也面临原料乳中嗜冷菌增多的风险,因此,了解不同冷藏时间原料乳中细菌群落结构变化对乳品工业持续发展具有重要意义。为此,该试验利用高通量测序技术和乳成分分析仪,分析和比较了4 ℃下贮藏24、72 h牦牛乳的细菌群落特征和理化特性。结果表明：冷藏24、72 h牦牛乳中第一、二优势菌属为乳球菌属、金黄杆菌属,该两类菌属的细菌分别占到冷藏24、72 h牦牛乳中细菌相对丰度的59.48%和67.51%。冷藏72 h牦牛乳中乳球菌属、金黄杆菌属相对丰度比冷藏24 h牦牛乳高出22.74%、3.56%,但是冷藏72 h牦牛乳中链球菌、不动杆菌属呈现降低趋势。冷藏24、72 h牦牛乳中假单胞菌属相对丰度较低,分别为1.69%和1.78%。冷藏72 h牦牛乳中酪蛋白、脂肪含量低于冷藏24 h牦牛乳,酸度增加到14.66 ºΤ。72 h的低温冷藏有助于控制牦牛乳细菌繁殖,维持乳品质。该研究为牦牛乳贮藏,干酪等乳制品加工,确保其品质和质量安全提供了理论依据。     

冻藏过程中南极磷虾蛋白理化特性和品质的变化

为了解冻藏南极磷虾理化性质和品质变化,本文测定了全虾和虾肉中不同蛋白组分含量变化,并采用二维电泳分析全虾样品的等电点和分子量分布,以水分含量、持水率、pH、硫代巴比妥酸反应物(TBARS)值为指标,进一步分析了蛋白品质的变化。结果表明:随冻藏时间的增加,南极磷虾全虾和虾肉盐溶性蛋白显著下降(p<0.05),碱溶性蛋白和非蛋白氮(NPN)显著上升(p<0.05)。二维电泳(2-DE)结果表明,盐溶性蛋白的蛋白点大多集中于pH4~6区域,水溶性和碱溶性蛋白在pH8~9也有分布;盐溶性蛋白的损失主要发生在肌球蛋白重链(210 kDa)和轻链(17~23 kDa)分子上;水溶性和碱溶性蛋白中蛋白点少量丢失。长期冻藏过程中,全虾和虾肉的含水量和持水率显著下降(p<0.05);全虾的pH和TBARS值明显升高(p<0.05),虾肉的pH和TBARS总体趋势略微上升(p>0.05)。各指标相关性分析表明,冻藏过程中虾品质指标的变化趋势具有一定的一致性。因此,随冻藏时间的增加,虾蛋白凝胶性质减弱,品质下降。     

UHT乳贮藏期间理化特性和感官品质的变化

为探讨超高温瞬时杀菌(ultra-high temperature instantaneous sterilization,UHT)乳的营养价值随贮藏时间的变化,对不同贮藏期UHT乳的理化特性和感官品质进行监测。在6个月的贮藏期内,UHT乳中脂肪、蛋白质、乳糖以及固形物的总量并无明显变化,维生素C和泛酸的含量均损失了约25%,游离氨基酸和钙离子分别增加了5.35%和6.73%。不同贮藏期UHT乳的黏度变化不显著(P>0.05),但粒径大小强烈依赖于贮藏时间,乳脂肪球和酪蛋白胶束的尺寸在贮藏初期分别增加了约38 nm和14 nm,然后分别稳定在约173 nm和612 nm。贮藏1个月的UHT乳样品在风味和口感方面整体表现较好,贮藏6个月后,UHT乳的感官品质大幅下降,出现了许多不良风味。     

MLM型结构脂的酶法合成及其理化性质分析

以醇解反应制得单甘酯和辛酸为底物,1,3-特异性固定化脂肪酶为催化用酶,在单因素试验的基础上,通过正交试验获得酯化反应制备MLM型结构脂质的最适条件：Lipozyme RM IM酶加入量9%(以底物质量计)、反应时间14h、反应温度40℃、单甘酯与辛酸(底物)物质的量比1:6;该条件下辛酸插入率达60.48%,其中92.84%的辛酸分布在甘油结构的1,3位上。经二级分子蒸馏纯化后得到的MLM型结构脂质,辛酸插入率达到73.34%;对其进行理化指标检测分析表明,该产品最低可达国家四级菜籽油的标准。     

间歇升温对采后香蕉李贮藏中酶促褐变的影响

以香蕉李为试材,研究不同的间歇升温对低温贮藏的李果实酶促褐变的影响。结果表明,李果实在冷藏20d 时启动冷害,多酚含量和PPO 活性逐渐下降,冷害指数显著增大,果实正常后熟过程受阻。同时,低温胁迫诱导了SOD 活性的增加,而冷害又激发CAT 或POD 活性的上升,说明受冷害果实的保护酶系统在抵抗逆境胁迫方面具有一定的协同作用。随着贮藏时间的延长,MDA 含量逐渐上升,冷害和褐变程度加剧。而间歇升温提高了SOD、POD 和CAT 的活性,抑制了活性氧的积累,减弱了膜脂过氧化的程度,延缓了冷害的发生,特别是间歇升温到18℃抑制冷害的效果更好,促进果实逐渐后熟,延迟了果实的衰老进程。而间歇升温到10℃贮藏前期虽然对冷害症状有所缓解,但果实成熟老化速度较快,贮藏后期老化的果实不耐低温贮藏,导致冷害加剧,果实褐变现象严重。     

不同品种南瓜淀粉的理化特性对比研究

对比研究了三种不同品种南瓜(蜜本、东升、翠栗)淀粉的理化特性。结果表明:三种南瓜淀粉中脂肪和蛋白质含量分别在0.15-0.25%和0.09-0.57%之间;直链淀粉和可溶性直连淀粉含量则依次在26.4-29.0%和4.48-7.40%之间,东升淀粉中直链淀粉和可溶性直链淀粉的含量明显高于其他两种南瓜淀粉。淀粉颗粒大小均在5-15μm之间,平均直径为10μm,属于偏小的淀粉颗粒,且多为无规则的椭圆或卵圆形。结晶结构均属于B型,结晶度分别为30.9%、42.7%、43.3%。东升和翠栗淀粉的起始糊化温度和糊化终止温度范围分别为73.21-82.76℃、78.66-89.88℃,而蜜本淀粉出现双峰现象,其糊化温度范围为69.00-75.67℃和77.70-86.17℃。蜜本淀粉具有较低的溶解度和膨胀度,凝沉稳定性较差,透光率最高;东升淀粉的溶解度和透明度较低,但凝沉性和冻融稳定性较好;而翠栗淀粉的溶解度和膨胀度最高,但冻融稳定性最差。     

发酵香肠在自然风干存贮过程中的理化指标变化

以猪肉为原料,采用传统中式方法制作香肠,定期检测成品香肠中各项理化指标的变化情况。结果表明:随着时间的延长,水分含量、pH值、红值逐渐降低;脂肪含量逐渐升高,脂肪的氧化水解导致的酸价、POV值、TBA值也逐渐增大。检测指标的变化趋势表明:自然风干存贮不利于香肠品质的提升,应设法加以改进。     

Physicochemical Properties and Consumer Acceptance of Wheat-Germinated Brown Rice Bread during Storage Time

Abstract: Selected physicochemical properties and consumer acceptance of bread prepared from composite flour (wheat:germinated brown rice:germinated glutinous brown rice flours at 60:30:10 ratio) were evaluated during storage for 0, 3, and 5 d, and compared with wheat bread (0 d, control). During storage, color profiles and water activity (from 0.947 to 0.932) of crumbs of composite flour breads slightly changed, but moisture content drastically decreased along with increasing crumb hardness (from 4.16 N to 10.37 N). Higher retrogradation in bread crumb was observed particularly for 5-d stored bread (ΔH = 2.24 J/g) compared to that of the fresh composite bread and the control (ΔH = 0.70 and 0.51 J/g, respectively). Mean (n = 116) overall liking score of the fresh composite flour bread (0 d) was slightly lower than that of the control (7.1 compared with 7.6 based on a 9-point hedonic scale). At least 76% of consumers would purchase the fresh composite flour bread if commercially available. Breads were differentiated by textural (moistness, smoothness, and softness) acceptability with canonical correlation of 0.84 to 0.87. The signal-to-noise ratio values of the 5-d stored breads were lower than the control, due mainly to the non-JAR (not-enough) intensity responses for moistness, smoothness, and softness; the mean drop of liking scores for these attributes ranged from 2.42 to 2.98. Flavor acceptability and overall liking were factors influencing consumers’ purchase intent of composite flour breads based on logistic regression analysis. This study demonstrated feasibility of incorporating up to 40% germinated brown rice flour in a wheat bread formulation. Practical Application: Our previous study revealed that flours from germinated brown rice have better nutritional properties, particularly gamma-aminobutyric acid (GABA), than the nongerminated one. This study demonstrated feasibility of incorporating up to 40% germinated brown rice flour in a wheat bread formulation. In the current U.S. market, this type of bread may be sold as frozen bread that would have a longer shelf life, or may be supplied as a food-service product that would be made-to-order or made fresh daily as currently practiced in some major grocery stores.     

柠檬酸处理鲜切猕猴桃在贮藏过程中抗氧化活性的变化

研究0.1、0.2、0.3 g/100 mL柠檬酸处理的鲜切猕猴桃在10 ℃贮藏10 d内抗氧化活性的变化。结果表明：鲜 切猕猴桃在贮藏期间抗氧化能力呈现下降的趋势,前期变化缓慢,后期下降趋势明显;同时,通过样品抗氧化能力 指标的测定可知,经过柠檬酸处理的鲜切猕猴桃抗氧化能力变化比未经过处理的鲜切猕猴桃抗氧化能力变化缓慢, 说明柠檬酸处理在贮藏过程中能更好的维持鲜切猕猴桃的抗氧化活性。     

Physicochemical Properties of Starch and Flour from Different Rice Cultivars

The starches and flours from four different rice cultivars were evaluated for composition, crystallinity characteristics, blue value, turbidity, swelling power, solubility, pasting properties, and textural and retrogradation properties. The amylose content of starches and flours from different rice cultivars differed significantly. The results showed that the physicochemical properties of rice starch and rice flour were correlated to amylose content. The crystallinity degree of rice starch and flour depended on amylose content. The blue value, turbidity value, and gel hardness were positively correlated to amylose content; however, the swelling power, solubility, and gel adhesiveness were negatively correlated to amylose content. Furthermore, the pasting properties and gel textural and retrogradation properties of rice flours were related to the structure properties of rice starch. And the characteristics of starch, protein, and lipid significantly influenced the turbidity, pasting properties, and gel textural and retrogradation properties of rice flours.     

Physiological and Genetic Properties of Tomato Fruits from 2 Cultivars Differing in Chilling Tolerance at Cold Storage

ABSTRACT:  Postharvest tomato fruits are cold-sensitive, and easy to develop chilling injury (CI) at cold storage. Information on physiological and genetic characteristics closely related to CI is necessary because it is significant to realize CI development regular and find sensitive indicators reflecting cultivar cold tolerance, which are the basics to prevent CI. In this study, we used 2 tomato cultivars (Lichun and Santiam) differing in cold tolerance to analyze ion leakage, malondialdehyde (MDA), proline, catalase (CAT), and peroxidase (POD) in postharvest fruits chilled at cold storage. Expression of cold-response gene LeCBF1 , a key regulator in cold-response, was also detected. Results showed that ion leakage, with a high correlation coefficient (0.9661) to CI index, exactly reflected injury development phase and degree; sharp increase of MDA and proline content appeared at and before the time of main development phase of CI (10 d); however, fluctuant CAT and POD activities could not sensitively reflect CI development, since their regular changes didn't appear until the main development phase ended. Thus, ion leakage, MDA, and proline content were effective indicators for CI analysis in postharvest tomato fruits. Although physiological analysis was effective in CI analysis, it was complex to be used in judging cold tolerance. Expression of LeCBF1 gene swiftly responded to low temperature within 1 h. In accordance with those physiological parameters, LeCBF 1 expression level was positively correlated with cold tolerance and showed a high correlation to CI index (−0.9176). These suggested that LeCBF1 analysis could be effectively used in fast testing the cold tolerance of tomato.