贮藏温度变化对壳蛋新鲜度的影响

该文以新鲜罗曼粉壳蛋为研究对象,研究4个贮藏温度变化处理组壳蛋新鲜度指标的变化,分别于0、10、20、30 d检测所有实验组壳蛋失重率、气室高度、哈夫单位、蛋黄指数、浓稀蛋白比和蛋清pH。结果表明,贮藏10～30 d,处理组2、处理组3、处理组4的失重率显著升高(P<0.05),而气室高度和浓稀蛋白比显著降低(P<0.05),除对照组外,所有处理组壳蛋pH呈现先升高后下降的趋势,处理组3和处理组4的蛋黄指数下降趋势更为明显。对照组和处理组1壳蛋的哈夫单位、蛋黄指数和浓稀蛋白比显著高于(P<0.05)处理组3和处理组4。在贮藏10～20 d时,处理组2的壳蛋pH显著高于(P<0.05)对照组和处理组1。因此,如果前10 d常温贮藏温度≥20℃时,引起壳蛋失重率的增加和哈夫单位的下降,与低温(4℃)贮藏相比,采用贮藏温度变化(常温-低温)贮藏壳蛋更容易引起壳蛋新鲜度指标的下降。     

不同包装形式对市售壳蛋新鲜度的影响

该文以罗曼粉壳蛋为研究对象，探究市售壳蛋常用包装形式对于壳蛋新鲜度的影响，研究纸托散装不重叠组、散装重叠组、泡沫缓冲组、纸盒组和塑料盒组5种常见包装组壳蛋新鲜度指标变化，25℃贮藏30 d,分别于0、10、20、30 d检测所有实验组壳蛋失重率、气室高度和气室直径、蛋黄指数、哈夫单位、浓稀蛋白比、蛋清pH。结果表明，贮藏10～30 d，纸托散装重叠组壳蛋失重率（2.33%～7.35%）、气室直径（2.46～3.17 cm）、蛋清pH(9.24～9.28)显著升高（P<0.05），而浓稀蛋白比（0.08～0.39）、蛋黄指数（0.27～0.41）显著下降（P<0.05）。纸盒组和塑料盒组壳蛋哈夫单位下降明显（P<0.05），泡沫缓冲组和纸托散装不重叠组壳蛋具有较低的气室高度。泡沫缓冲组壳蛋失重率（0.62%～5.46%）、气室直径（2.02～2.62 cm）、蛋清pH(9.05～9.26)较低，而蛋黄指数（0.27～0.48）较高。进一步通过主成分分析能较好区分塑料盒、泡沫缓冲包装组与其他3个包装组壳蛋，新鲜度指标贡献情况具有一定差异。因此，不改变环境条件，采用泡沫缓冲...     

运输后贮藏过程中鸡蛋品质变化的研究

本研究以罗曼粉鸡鸡蛋为原料,分别使用轿车、厢式货车进行实际运输实验,记录运输振动情况,测定运输后常温贮藏期间鸡蛋的失重率、哈夫单位、蛋黄指数、蛋清pH和蛋黄膜强度等指标,得到鸡蛋新鲜度变化情况。结果表明,运输振动强度方面,轿车车厢低于货车内部,货车内部振动强度由小至大分别是前下、前上、后下和后上,各位置垂直方向加速度均显著(P<0.05)强于水平方向。贮藏期间鸡蛋新鲜度不断下降,后上组哈夫单位下降最快,贮藏21 d时与对照组存在显著差异(P<0.05),实验组鸡蛋蛋黄膜强度显著(P<0.05)低于对照组。贮藏期间鸡蛋失重率上升,蛋黄指数下降,蛋清pH升高,但各组间差异均不明显。说明运输中的振动能够加速贮藏期间鸡蛋新鲜度的下降,且运输时振动强度越大,其对鸡蛋品质影响越大。本研究为今后深入探索振动对鸡蛋贮藏期间品质变化机理和禽蛋产业的发展提供参考。     

鸡蛋新鲜度指标与贮藏天数相关性研究

目的 分析鸡蛋新鲜度指标与贮藏天数的相关性, 确定新鲜度指标数值显著变化的时间, 建立新鲜度与贮藏时间相关性模型。方法 2 d为一个时间点, 设立12个实验组, 每组5枚鸡蛋, 按照标准中鸡蛋新鲜度评定指标重复3次测定鸡蛋相对密度、气室高度、哈夫单位、蛋黄指数、pH值、失重率。根据Pearson相关系数评价贮藏天数与鸡蛋新鲜度各指标之间的相关程度, Duncan法评价贮藏天数与鸡蛋新鲜度各指标之间的差异显著程度。结果 鸡蛋新鲜度各指标与贮藏天数之间显著相关(P<0.05), 各新鲜度指标数值出现显著变化的时间各不相同, 各天数之间的鸡蛋失重量、失重率差异显著(P<0.05)。结论 本研究所建立的鸡蛋新鲜度与贮藏时间的相关性模型, 可作为鸡蛋新鲜度评价模型。     

气调包装、清洗涂膜及紫外杀菌处理对鸡蛋品质影响的比较分析

为研究不同贮藏方式对鸡蛋品质的影响,采用气调包装、清洗涂膜和紫外杀菌的组合处理方式,将新鲜鸡蛋分为6组,对其进行贮藏保鲜实验。在室温下贮藏42 d,测定鸡蛋失重率、哈夫单位、蛋黄指数、蛋清p H以及菌落总数的变化,并对蛋壳表面的真菌情况进行了初步的分析。结果显示:各气调包装组均能有效抑制失重率和蛋清p H的上升,并能有效抑制鸡蛋哈夫单位和蛋黄指数的降低,与对照组差异显著(p≤0.05);清洗涂膜能在一定程度上保鲜鸡蛋,但与对照组相比,鸡蛋的失重率、哈夫单位、蛋黄指数、蛋清p H等指标差异不显著;清洗涂膜和紫外处理对蛋壳表面的细菌具有良好的抑制作用;PCR测序结果显示蛋壳表面的真菌共计13种,以赛氏曲霉(Aspergillus sydowii)为主,占蛋壳表面真菌总量的80.91%。结论:经过清洗涂膜、紫外杀菌和气调包装复合处理的鸡蛋在贮藏期(42 d)内,失重率、哈夫单位、蛋黄指数、蛋清p H和细菌菌落总数等品质指标均优于其他处理组,能最大程度抑制鸡蛋腐败变质。     

不同处理对绿壳鸡蛋保鲜效果的研究

采用三种不同的处理方法对绿壳鸡蛋进行保鲜效果的研究,测定了鸡蛋的外部品质和内部品质的变化。结果表明,涂膜组效果最好,其次为热处理组。哈夫单位(H.U)和蛋黄指数与蛋的新鲜度呈显著的正相关;挥发性盐基氮(TVBN)含量与新鲜度呈显著的负相关。第21d开始,三个处理组间的哈夫单位和蛋黄指数有显著的差异(P<0.05);第28d时,对照组、热处理组和涂膜组挥发性盐基氮含量分别为9.095、8.270和7.560mg/100g,差异显著(P<0.05)。蛋壳厚度、蛋壳强度、蛋黄颜色、气室直径和胆固醇含量在各处理组间没有显著的差异(P<0.05)。     

壳聚糖涂膜对鸡蛋品质的影响

通过对新鲜鸡蛋涂擦不同质量浓度的壳聚糖溶液,旨在研究壳聚糖对鸡蛋品质的影响。试验将300 枚新鲜鸡蛋随机分成6 组,分别涂上0、0.5、1.0、1.5、2.0g/100mL 和2.5g/100mL 壳聚糖溶液,25℃条件下贮存5周。每周从每个处理中取10 枚鸡蛋测定鸡蛋失重率、哈夫单位、蛋黄指数和蛋清pH 值。结果表明,第5 周与第1 周相比,不涂壳聚糖的鸡蛋失重率和蛋清pH 值显著升高(P ＜ 0.05)、哈夫单位和蛋黄指数显著低(P ＜ 0.05) 。5 周时,与不涂壳聚糖的鸡蛋相比,所有涂壳聚糖的鸡蛋失重率显著降低(P ＜ 0.05),蛋黄指数显著升高(P ＜ 0.05);涂1.0、1.5、2.0g/100mL 和2.5g/100mL 壳聚糖的鸡蛋哈夫单位显著升高(P ＜ 0.05),蛋清pH 值显著降低(P ＜ 0.05);涂1.5、2.0g/100mL 和2.5g/100mL 壳聚糖的鸡蛋间比较,蛋质量损失率、哈夫单位、蛋黄指数和蛋清pH 值差异均不显著(P ＞ 0.05)。用0.5g/100mL 壳聚糖涂擦的鸡蛋5 周时降到C 级,相当于不涂壳聚糖的鸡蛋3 周时的级别;用1.0、1.5、2.0g/100mL 和2.5g/100mL 壳聚糖处理的鸡蛋5 周时降到B 级,相当于不用壳聚糖处理的鸡蛋2 周时的级别。该实验证明壳聚糖能够延长鸡蛋货架期。     

热水-涂膜复合处理对鸡蛋保鲜的影响

为延长鸡蛋保鲜期,分别对新鲜鸡蛋采用1%壳聚糖与1%石蜡的混合液进行涂膜处理、90～95℃热水处理以及先进行热水处理再涂膜的复合处理,再于20℃进行20 d贮藏保鲜试验,同时对表征鸡蛋新鲜度的指标进行测定,包括感官指标、哈夫单位（H.U）、蛋黄指数、鸡蛋失重率。结果表明：复合处理组的保鲜效果最好,哈夫单位、蛋黄指数、失重率都优于其他处理组,其次是涂膜组,热水处理组效果较差。     

纳米植物糖原/壳聚糖复合涂膜鸡蛋保鲜效果研究

研究纳米植物糖原与壳聚糖混合膜对鸡蛋保鲜效果的影响。设置3个组别进行试验,分别是空白组,45℃处理组,植物糖原组,通过感官评定和测定鸡蛋气室高度、蛋黄高度、失水率、哈夫单位、蛋清p H值和鸡蛋总菌数来评价鸡蛋的保鲜效果。结果表明纳米植物糖原涂膜组的鸡蛋的各项指标均优于空白组和45℃处理组;贮藏30 d后植物糖原涂膜保鲜感官评定蛋黄扁平、浓蛋清几乎看不见、系带极细,脱落,测得涂膜组鸡蛋气室高度为4 mm,蛋黄指数为0.66,失水率为3.01%,哈夫单位为72.5,蛋清p H值为7.5,菌落总数为785 cfu/g。     

含茶多酚的壳聚糖涂膜对鸡蛋保鲜效果的影响

用茶多酚和壳聚糖制成的复合涂膜液对鸡蛋进行涂膜处理,以感官指标、失重率、蛋黄指数、蛋清pH值、哈夫单位为质量指标定期取样分析测定,研究所制成的涂膜液在室温条件下对鸡蛋的保鲜效果。结果表明,和对照相比,含茶多酚的壳聚糖涂膜液能较好地保持鸡蛋的新鲜度和品质,尤其以1.5%的壳聚糖溶液联合200mg/kg茶多酚制得的涂膜液保鲜效果最好,经此涂膜液处理后的鸡蛋室温下贮存35d,失重率为1.89%,蛋黄指数为0.26,哈夫单位为60.109,蛋清pH值为8.20。     

Storage effects on dielectric properties of eggs from 10 to 1800 MHz

ABSTRACT:  The dielectric constant and loss factor of egg albumen and egg yolk over the frequency range from 10 to 1800 MHz were measured at 24 °C at weekly intervals during 5-wk storage at 15 °C. Moisture and ash contents of albumen and yolk, as well as Haugh unit and yolk index, were also measured. The dielectric constant and loss factor of albumen were higher than those of yolk. Linear relationships were evident between the log of frequency, below about 1000 MHz, and the log of loss factor of albumen as well as that of yolk. The dielectric constants of albumen and yolk at 10 MHz were lower than those of fresh albumen and yolk when eggs were stored at 15 °C for 1 wk. However, after 2 wk in storage these dielectric constants rose and remained at higher levels for the rest of the 5-wk period. At frequencies of 100 MHz and higher, the dielectric constant was essentially constant during the entire storage period. Storage had much less influence on the loss factor of either albumen or yolk. In general, the moisture content and ash content of albumen and yolk decreased slightly as eggs aged. The moisture content of yolk increased somewhat with storage, and there was a corresponding decrease in albumen moisture content. The freshness qualities, Haugh unit and yolk index, also decreased as eggs aged. No obvious correlation between dielectric properties and moisture content, ash content, Haugh unit, or yolk index was observed.     

Assessment of egg freshness by prediction of Haugh unit and albumen pH using an artificial neural network

Eggs are a good source of high quality protein and knowing their quality (physical and chemical properties) during storage is of great importance. Thus, the aim of this research was to design a computer vision system to assess egg freshness during storage time. To this end, 210 intact eggs were collected and stored for 30 days under room conditions (25?±?2 °C and 20?±?3%). After imaging, every other day, some internal and external quality characteristics including yolk height, yolk and albumen pH, yolk and albumen density and Haugh unit (HU) were measured as destructive parameters and area index (D) egg weight as non-destructive parameters. Based on Pearson correlation coefficients, area index were significantly correlated with all destructive variables (p?<?0.05). In order to predict egg freshness, artificial neural network was trained by Levenberg–Marquardt, scaled conjugate gradient, Bayesian regulation, resilient and radial basis algorithms. The best result of artificial neural network for HU and albumen pH prediction was achieved by the Levenberg–Marquardt algorithm with the correlation coefficient of 0.93 and 0.87, respectively.     

大蒜、葱白和花椒复配物涂膜对鸡蛋在高温下贮藏保鲜效果的影响

以新鲜鸡蛋为原料,大蒜、葱白和花椒按质量比20:10:1复配制备保鲜原液,原液加水等质量比稀释至原液的50%和25%,分别用上三个浓度复配物涂膜鸡蛋,并设置对照组,在温度为37℃的恒温培养箱中贮藏,检测复配物对鸡蛋感官品质、失重率、哈夫单位、蛋黄指数和蛋清pH的影响。结果表明:对照组蛋品质量在第10 d已严重下降,第20 d全部散黄,而复配物涂膜组均有不同程度保鲜效果。其中大蒜、葱白浸泡花椒原汁(即100%)复配物37℃环境中贮藏20 d后感官性状良好,失重率4.61%,哈夫单位63.77,蛋黄指数0.38,蛋清pH为9.67,保鲜效果最好。     

Effects of mineral oil coating on internal quality of chicken eggs under refrigerated storage

The selected internal qualities (weight loss, Haugh unit, yolk index, and albumen pH) of noncoated and mineral oil‐coated chicken eggs during 15 weeks of storage at 4 °C and/or during 5 weeks of storage at 25 °C were evaluated. Results indicated that, without refrigeration, the noncoated and mineral oil‐coated eggs rapidly changed from AA to C and B grades as measured by Haugh unit, respectively, after 5 weeks of storage. However, the AA quality of the noncoated eggs could be maintained under refrigerated storage (4 °C) for at least 5 weeks. The mineral oil coating and refrigerated storage (4 °C) synergistically minimised weight loss and preserved the albumen and yolk qualities of chicken eggs during a long‐term storage. At 4 °C, the mineral oil‐coated eggs preserved the initial AA grade for at least 15 weeks with l.19% weight loss.     

鸡蛋内部品质与其呼吸强度的关系

贮藏期鸡蛋品质的变化与呼吸作用息息相关,为了进一步明确鸡蛋内部品质与其呼吸强度之间的关系,本研究选取同一品种的鸡蛋作为实验样本,利用呼吸测定仪测定鸡蛋的二氧化碳呼吸强度,通过SPSS 19.0软件分别分析鸡蛋哈夫单位、蛋白高度、pH值、黏度、蛋黄指数、蛋黄比例以及蛋黄色度与呼吸强度间的关系。结果表明：鸡蛋哈夫单位、蛋白高度及黏度与呼吸强度之间呈极显著正相关（P＜0.01）;pH值与呼吸强度之间呈极显著负相关（P＜0.01）;蛋黄指数、蛋黄色度与呼吸强度之间呈极显著正相关（P＜0.01）;而蛋黄比例与呼吸强度间相关性较小;此外,pH值与黏度、蛋黄指数、蛋黄色度间均存在极显著负相关（P＜0.01）;黏度与蛋黄指数、蛋黄色度之间呈极显著正相关（P＜0.01）;蛋黄比例与其他参数相关性较小。总之,在鸡蛋内部品质参数中,鸡蛋哈夫单位、蛋白高度、蛋黄指数、pH值、黏度及蛋黄色度对呼吸强度影响较大。     

Plasticizer types and coating methods affect quality and shelf life of eggs coated with chitosan

ABSTRACT:  Effects of different plasticizer types (glycerol, propylene glycol, and sorbitol) and coating methods (brushing, dipping, and spraying) on the internal quality and shelf life of chitosan-coated eggs were evaluated during 5 wk of storage at 25 °C. The Haugh unit and yolk index values suggested that chitosan coating, irrespective of the plasticizer types, extended the shelf life of eggs by almost 3 wk at 25 °C compared with noncoated eggs. After 5 wk of storage, plasticizer types did not significantly affect the quality (weight loss, Haugh unit, and yolk index) of chitosan-coated eggs. However, there was an observable trend indicating that use of sorbitol rather than propylene glycol and glycerol as a plasticizer was better in reducing weight loss (whole egg) of chitosan-coated eggs during a 5-wk storage. After a 5-wk storage, there were no significant differences in weight loss and weight of albumen and yolk among chitosan-coated eggs, regardless of the coating methods. However, both brushing and dipping methods yielded chitosan-coated eggs with better yolk (higher yolk index values) and albumen (lower pH) qualities than did the spraying method. During 3 to 5 wk of storage, the Haugh unit values of chitosan-coated eggs by the brushing method were higher than or comparable to those by dipping or spraying. Therefore, coating of eggs with chitosan using sorbitol as a plasticizer and by the brushing method may offer a protective barrier in preserving the internal quality and thus extending shelf life of eggs.     

MAP storage of shell hen eggs, Part 1: Effect on physico-chemical characteristics of the fresh product

The aim of this study was to compare some physico-chemical properties (O₂ and CO₂ in the package headspace, weight loss, pH, albumen and yolk water content and colour, Haugh unit) of non packed eggs and eggs packed in high barrier plastic pouches with three atmospheres (air, 100% N₂, 100% CO₂) during 28 days of storage at 25 °C. Modified atmosphere packaging (MAP) permitted a strong reduction of the weight loss from the product. While the greatest quality decline was observed for the control eggs (not packed), eggs packed in CO₂ maintained the initial values of Haugh unit during storage and the albumen pH was about 2 units lower than in the control group. Nevertheless, the light yellow colour of CO₂ sample albumen deepened and the shell gradually developed a powdery surface. MAP with 100% N₂ did not promote any additional benefits to the eggs in comparison with the product packed in air.