花生仁与核桃仁贮藏货架期预测模型

采用加速贮藏试验,研究花生仁与核桃仁贮藏中脂肪氧化的动力学及其货架期预测模型。花生仁和核桃仁分别采用真空和露空两种贮藏方式贮藏于0～50℃。以过氧化值(POV)为指标,通过对不同温度下POV的测定,建立了POV与贮藏时间(t)的一级反应动力学方程以及反应速率(k)与贮藏温度(T)的Arrhenius方程;低温和真空贮藏时,氧化反应的活化能(EA)明显升高,证明低温和真空条件可延缓果仁的氧化酸败;两种贮藏方式下,核桃仁反应活化能(EA)均小于花生仁EA,表明核桃仁氧化稳定性低于花生仁。两种果仁的一级化学反应动力学模型和Arrhenius方程均具有较高的拟合精度(R2>0.95),建立的模型对货架期的预测值与实测值接近(RE<10%),表明论文得到的预测模型可快速准确的预测0～50℃条件下花生仁与核桃仁贮藏的货架期。     

漂白紫胶涂膜对核桃仁氧化酸败抑制效果的研究

采用漂白紫胶溶液和SiO2溶液涂膜对核桃仁进行抑制氧化酸败的研究.结果表明:漂白紫胶涂膜对核桃仁氧化酸败具有抑制效果,漂白紫胶涂膜可以显著抑制核桃仁的氧化酸败过程.真空包装对抑制核桃仁的氧化酸败也有一定的作用.     

控制腊肠脂肪酸败的研究

本文针对腊肠在贮藏过程中的脂肪氧化酸败问题,运用综合控制措施加以解决.结果表明添加AO3抗氧化剂后,腊肠在30℃、65%RH和1520℃、3040%RH条件下贮藏时均能显著延缓腊肠酸败的发生.同时发现新包装材料结合使用脱氧剂对控制腊肠的脂肪氧化也有明显效果.     

茶多酚对干果类食品抗氧化作用的研究

为了延长言含油脂的干果类食品的保质期，研究了茶多酚、维生素C（Vc）对炒熟花生仁、核桃仁油脂氧化酸败的抑制作用。通过测定常温贮存两个月的样品中过氧化值（POV）的变化来检测炒熟花生仁和核桃仁油脂的氧化酸败程度。结果表明，茶多酚、Vc对炒熟花生仁和核桃仁油脂氧化酸败确实有抑制作用。     

用改进的α—硫代巴比妥酸（TBA）值法来测定肉类食品中脂肪的氧化

肉类和含脂肪的食品在贮藏期间,由于脂肪的氧化酸败产生不良的气味而降低了质量,甚至完全不能食用。脂肪的氧化酸败是一个极其复杂的化学反应过程,如欲在化学上评价其氧化的程度,只有用发生在其全过程的化学反应来评价。通常测定氧化酸败的方法是基于对反应的中间产物或最终产物的定     

小麦胚芽贮藏过程中的酸败变质机理

小麦胚芽含有丰富的优质蛋白、多不饱和脂肪酸和VE等多种营养素,同时也富含脂肪酶、脂肪氧化酶和酯酶等多种酶类。新鲜小麦胚芽贮藏两周左右,就会在各种酶和微生物的协同作用下酸败变质,从而极大限制了小麦胚芽的高效利用。本文系统阐述了小麦胚芽脂肪酶和脂肪氧化酶的种类、酶学特性及其催化机制;并从小麦胚芽脂质的脂肪酶催化水解、自动氧化、脂肪氧化酶催化氧化以及微生物污染等多角度分析了小麦胚芽贮藏过程中的酸败变质机理。对小麦胚芽脂肪酶和脂肪氧化酶的深入了解,有助于研发可靠的小麦胚芽稳定化技术与装备,为其进一步深加工创造条件。     

包装对巴旦杏仁油脂氧化和抗氧化能力的影响

以经过加工的去壳巴旦杏仁为材料,研究不同包装材料对其酸价、过氧化值、TBA值、总酚含量、VE含量和DPPH自由基清除能力的影响,以期了解包装材料对巴旦杏仁贮藏过程中油脂氧化和抗氧化能力的影响.结果表明:巴旦杏仁在贮藏过程中发生油脂的氧化酸败,表现为过氧化值和酸价上升,TBA值增加;采用EVOH共挤膜包装可显著降低其贮藏过程中酸价和过氧化值的增加幅度,抑制TBA值增加,减轻脂肪的氧化酸败;并保持较高的自身抗氧化物质总酚和VE含量,减缓DPPH自由基清除能力的下降,相对较好地维持组织的抗氧化能力.     

广式腊肠质量的评价及控制

广式腊肠以其独特的外观和风味闻名遐迩.广式腊肠制品在贮存过程中由于脂肪的酸败及腐败微生物的增殖影响了腊肠的保质期.本文在着重分析广式腊肠贮藏过程制品中脂肪酸的氧化酸败机制及其时腊肠质量影响的基础上,介绍了国内外对腊肠质量的评价和控制以及延长腊肠保质期方面的研究.     

不同包装方式对薏米挂面贮藏品质的影响

该文分别对半封闭纸包装、全封闭纸包装、全封闭PE包装的薏米添加量为10%和50%(质量分数)的挂面进行贮藏实验,分析自然贮藏条件下其食用品质和理化指标的变化。结果表明,各处理组的食用品质随着贮藏时间的延长均逐渐劣变。当贮藏期超过6个月时,薏米挂面失去食用和商品价值。此外,薏米挂面贮藏期间过氧化值、丙二醛含量与各食用品质均呈现极显著相关性(P<0. 01),说明薏米挂面中脂肪的酸败氧化程度对面条食用品质具有重要的影响。与半封闭纸包装和全封闭纸包装贮藏的薏米挂面相比,以全封闭PE包装贮藏的薏米挂面酸败氧化速度较慢,可以有效地减缓挂面食用品质的劣变。因此,最好以全封闭PE包装贮藏薏米挂面,且贮藏期(保质期)不得超过6个月。     

香辛料提取物对速冻牛肉丸脂肪氧化控制的研究

研究添加迷迭香、丁香、肉桂提取物对－18℃冻藏牛肉丸脂肪氧化、颜色稳定性和感官评定的影响。测定结果以肉丸在储存期间的硫代巴比妥酸值(TBARS值)、过氧化物值(PV值)、颜色(L*、a*值)和感官评定指标。结果表明：与对照组相比,随着贮藏时间的增加,添加香辛料提取物的各处理组能够显著延缓脂肪氧化(P＜0.05);亮度L*值呈现出先下降后上升的趋势,而红度a*值逐渐降低;贮藏120d后,添加香辛料提取物的各处理组具有较好的滋气味与颜色。表明添加香辛料提取物在一定程度上可以减缓脂肪氧化速度,同时还可以改善风味,掩盖脂肪氧化酸败味。     

The effect of salt concentration on rancidity in Gaziantep cheese

Gaziantep cheese is a non‐fermented and enzyme clotted type cheese. The changes in oxidative and hydrolytic rancidity in the cheese were analysed during its storage. Storage conditions were selected as 4, 10 and 20°C and 90, 170, 200 and 230 g kg⁻¹ salt solutions by considering the traditional storage conditions. Oxidative rancidity increased with increasing temperature and NaCl concentration in the brine. Hydrolytic rancidity increased with increasing temperature and decreasing salt content of the cheese. The extent of oxidative rancidity was found to be higher than hydrolytic rancidity. The results of this study showed that the storage temperature should not be higher than 10°C and brine concentration must be higher than 90 g kg⁻¹ and lower than 230 g kg⁻¹ to minimize lipid oxidation. Gaziantep cheese was organoleptically examined after 2 months of storage at 20°C and in 90, 170 and 230 g kg⁻¹ salt solutions, and it was found that even at a peroxide value around 1 meq kg⁻¹, acceptable levels of changes in flavour were observed. Sensory analysis results showed that textural properties of Gaziantep cheese changed with salt concentration of the brine. © 1999 Society of Chemical Industry     

Peanut and Walnut Rancidity: Effects of Oxygen Concentration and Relative Humidity

Accelerated tests for oxidative rancidity of blanched peanuts, blanched dry-roasted peanuts, blanched oil-roasted peanuts and shelled Persian walnuts were performed at high and low oxygen content at controlled intermediate and low relative humidities. The results confirmed and quantified the importance of oxygen content, relative humidity and roasting process in the oxidative rancidity of peanuts and walnuts. There is a potential to extend shelf-life of roasted peanuts and walnuts by edible coatings with low oxygen permeability or nitrogen-flushing with oxygen barrier packaging. Static headspace chromatography was useful to monitor oxidative rancidity in walnuts and roasted peanuts.     

Color and Oxidative Rancidity of Gamma and Electron Beam-Irradiated Boneless Pork Chops

Color and oxidative rancidity were determined for chilled (3 ± 2°C) and frozen (?17 ± 3°C) boneless pork chops packaged in vacuum or air and irradiated to an absorbed dose of 0, 1.5 or 2.5 kGy (chilled) or 0, 2.5 or 3.85 kGy (frozen) of electron beam or cobalt⁶⁰ irradiation. Irradiation of vacuum-packaged chops produced redder, more stable (color and rancidity) product. More pronounced oxidative rancidity and less stable display color were noted for samples irradiated in aerobic packaging. Irradiation source had varying but limited effects on color and rancidity. Optimum packaging conditions can control color and rancidity changes in boneless chops, thereby enabling irradiation to be a useful intervention technology.     

挂面加工和储藏中的酸败及控制技术研究

挂面在加工和储藏过程中产生的酸败严重影响了其品质。对挂面酸败产生的机制和控制技术进行研究,采用高效液相色谱分析A1小麦粉、新鲜和储藏40 d挂面的脂肪酸组成和含量,并分析其酸价、过氧化值和TBA值的变化,结果显示亚油酸(C18∶2)、亚麻酸(C18∶3)发生氧化分解是挂面酸败产生的主要原因。分析五种小麦粉以及添加脂溶性、水溶性迷迭香A1小麦粉生产的挂面加工和储藏过程中酸价、过氧化值和TBA值的变化,结果表明采用不易产生酸败的小麦粉和添加一定量的脂溶性、水溶性迷迭香生产挂面可延缓挂面的酸败。     

拉曼光谱法检测灵芝孢子油氧化酸败

采用拉曼光谱法直接监测灵芝孢子油中氧化酸败过程中不饱和双键特征峰的变化规律,研究了特征峰的强度与孢子油氧化酸败程度的关系。结果表明,特征峰强度随孢子油酸值、过氧化值的增加而下降,特征峰的面积与孢子油酸值之间存在着良好的线性关系,并进一步测定了灵芝孢子油氧化酸败的动力学参数。建立了用拉曼光谱快速检测灵芝孢子油氧化酸败度的新方法。对该方法的有效性进行评估,并用该方法筛选出有效的灵芝孢子油抗氧化剂。     

Lipoxygenase activity in walnuts and almonds

The objective of this experiment was to investigate lipoxygenase (LOX) activity in walnut or almond homogenates. Walnut or almond kernels were heated with hot air at 55 °C for 2 or 10 min, or 60 °C for 2 or 10 min. The homogenates of untreated or heat treated walnut kernels exhibited greater LOX activity than the homogenates of untreated or heat treated almond kernels. Short-time heat treatments of 55 °C for 2 min or greater reduce LOX activity, retard the development of oxidative rancidity, and extend the shelf-life of walnuts and almonds during distribution and storage. Short-time heat treatments of walnut or almond kernels designed to control insect pests for international trade did not promote rancidity when compared to untreated walnuts or almonds.     

RANCIDITY OF WALNUTS AND ALMONDS AFFECTED BY SHORT TIME HEAT TREATMENTS FOR INSECT CONTROL

Short time heat treatments effectively control insect contamination of nuts containing substantial quantities of polyunsaturated fatty acids susceptible to oxidative rancidity. Walnut kernels contain greater concentrations of polyunsaturated fatty acids than almond kernels. The objectives of this research were to investigate the lipid stability of shelled walnuts and almonds as affected by short time heat treatments and accelerated storage temperatures. Heating treatments were at 55C for 2 min, 55C for 10 min, 60C for 2 min or 60C for 10 min to simulate predetermined deinfestation treatments. Untreated control and heat treated shelled walnut and almond kernels were stored at 25C for 5, 15, 30 and 60 days or 35C for 2, 5, 10 and 20 days to simulate the shelf lives of walnut and almond kernels at 4C for 2 years. Oils extracted from untreated and short time heat treated walnut kernels exhibited higher peroxide values than oils extracted from untreated and short time heat treated almond kernels under equivalent conditions. Oils extracted from untreated walnut kernels exhibited significantly (P ± 0.05) higher peroxide values than oils extracted from short time heat treated walnut kernels after 5, 15, 30, and 60 days of storage at 25C, or after 2, 5, 10, or 20 days of storage at 35C. Oils extracted from untreated almond kernels exhibited higher peroxide values than oils extracted from short time heat treated almond kernels after 5, 15, 30, or 60 days of storage at 25C, or after 2, 5, 10 or 20 days of storage at 35C. Oils extracted from untreated walnut kernels and oils extracted from short time heat treated walnut kernels exhibited higher peroxide values than oils extracted from almond kernels after storage at 25C or 35C. Short time heat treatment does not enhance development of rancidity during accelerated storage of walnut or almond kernels.     

米糠酸败诱导的蛋白质氧化对米糠清蛋白界面性质的影响

研究米糠酸败诱导的氧化修饰对米糠清蛋白界面性质的影响。结果显示,米糠酸败会诱导米糠清蛋白发生羰基化和巯基氧化反应。米糠清蛋白的乳化性、乳化稳定性、起泡能力和起泡稳定性与其羰基含量、α-螺旋/β-折叠呈极显著（P＜0.01）负相关,与游离巯基含量、表面疏水性、Zeta电位绝对值、溶解度呈极显著（P＜0.01）正相关。结果表明,米糠氧化酸败产物诱导米糠清蛋白通过蛋白质-蛋白质相互作用（二硫键、非二硫共价键、疏水作用力等）形成可溶性和不可溶的聚集体,导致蛋白质分子柔性和表面疏水性下降,分子间静电斥力减弱,进而对米糠清蛋白的界面性质产生负面影响。     

米糠酸败对米糠蛋白体外胃蛋白酶消化产物结构特征的影响

将新鲜米糠贮藏不同时间后进行稳定化和脱脂制备米糠蛋白,研究米糠酸败对米糠蛋白体外胃蛋白酶消化产物结构特征的影响。结果表明：随着米糠酸败程度增加,米糠清蛋白亚基、谷蛋白酸性亚基和球蛋白亚基完全被胃蛋白酶消化降解的时间先提前后延迟,而米糠谷蛋白碱性亚基和醇溶蛋白亚基表现为更难被胃蛋白酶消化;分子质量分布和粒径分布结果表明,米糠酸败过程中形成的米糠蛋白氧化聚集体会抑制米糠蛋白体外胃蛋白酶消化;此外,随着米糠酸败程度的增加,米糠蛋白体外胃蛋白酶消化产物内源荧光峰位的红移幅度先增大后减小,表面疏水性则逐渐下降。总之,米糠酸败导致的米糠蛋白氧化对米糠蛋白消化产物的共价交联状态、聚集行为和表面疏水性等结构特征产生了重要影响。     

小麦胚芽贮藏期内脂质水解酸败机理解析

以小麦胚芽为研究对象,构建脂质水解酸败的模拟体系以及原位体系,解析小麦胚芽贮藏期内脂质水解酸败的机理。结果表明:光照、氧气和脂肪氧合酶未对小麦胚芽模拟体系中的游离脂肪酸含量产生明显影响,而脂肪酶则显著提升游离脂肪酸生成量;此外,游离脂肪酸生成量随水分活度增加而增加,于水分活度为0.75时达峰值,且小麦胚芽内部结合水和不易流动水含量也呈显著增加趋势,水分以及脂质流动性增加;小麦胚芽原位体系中游离脂肪酸含量随贮藏时间延长而逐渐增加,磷脂酰胆碱含量恰相反,且小麦胚芽脂质体膜遭到破坏,游离出的甘油三酯聚集形成油滴。由此可见,小麦胚芽脂质水解酸败模式主要表现为其脂质体膜中的磷脂酰胆碱降解而释放甘油三酯,而后甘油三酯经由脂肪酶催化水解生成大量的游离脂肪酸,从而产生水解酸败现象。