脂肪氧化初期脂肪酸与氧化指标变化相关性研究

以牦牛肾周脂为研究对象,研究了其在储藏期(15±1)℃下脂肪酸与氧化指标(TBARS和PV)在动态变化中的相关性。结果表明:牦牛肾脂脂肪氧化初期发生于储藏期第0～25天。比较脂肪酸与氧化指标变化后发现,SFA与TBARS(和PV)呈较高正相关(≥0.971),MUFA和PUFA与TBARS(和PV)具有较低负相关系数(≤0.926)。在MUFA中,C16:1和C18:1与氧化指标的负相关系数较低,分别为-0.932和-0.981;在PUFA中,除CLA和LA外,其他多不饱和脂肪酸与氧化指标的相关性均较好(≥0.891)。因此,TBARS和PV可以被用于间接评估脂肪在工业开发前储存期间不饱和脂肪酸的含量分布状态。     

草鱼脆化过程中腹内脂肪酸组成变化

以不同脆化期的草鱼腹内脂肪为原料,采用气相-色谱质谱(GC-MS)联用技术,研究草鱼脆化过程中腹内脂肪酸组成变化。结果显示,不同脆化期的草鱼腹内脂肪中共检出19种脂肪酸,其中饱和脂肪酸(saturated fatty acid,SFA)7种,单不饱和脂肪酸(monounsaturated fatty acid,MUFA)2种,多不饱和脂肪酸(polyunsaturated fatty acid,PUFA)10种。随着脆化时间的延长,MUFA含量显著增加,PUFA、n-6 PUFA含量显著减少(p0.05)。整个脆化过程中,SFA∶MUFA∶PUFA的比值近似于1∶2∶1,以普通草鱼最为接近。而n-3 PUFA在脆化20 d时开始减少(p0.05),始终低于普通草鱼。n-6/n-3 PUFA的比值为3.36%±0.04%~4.10%±0.04%,脆化20 d时最高。研究表明,虽然脆化改变了腹内脂肪酸的组成,但脆肉鲩腹内脂肪仍具有较好的开发价值。     

油瓜种仁油与8种食用油理化及挥发性成分对比分析

以云南西双版纳油瓜种仁油为原料,对比分析核桃油、花生油、黑芝麻油、玉米胚芽油、大豆色拉油、大豆油、橄榄油、葵花籽油共9种油脂的理化成分、矿物质含量及脂肪酸组成。结果表明,油瓜种仁油过氧化值为(5.90±0.81)mmo L/kg,水分及挥发物为(0.31±0.07)%,杂质含量为0.25%,酸值为(11.21±0.13)mg KOH/g。矿物质含量(除锰含量)位列所检油脂第二0.262 mg/kg,铜含量位列第七0.284 mg/kg,磷、锌、铁、镁、钙、铜、钠、钾含量均最高。油瓜种仁油共检出9种脂肪酸,以亚油酸45.89%、棕榈酸29.85%、油酸14.14%为主。MUFA(单不饱和脂肪酸)∶PUFA(多不饱和脂肪酸)∶SFA(饱和脂肪酸)=1∶3.3∶2.7。n-3 PUFAs∶n-6 PUFAs=1∶63。建议与橄榄油复配,复配后MUFA∶PUFA∶SFA=1∶1∶0.8。或油瓜种仁油、橄榄油、核桃油三者复配,复配后MUFA∶PUFA∶SFA=1∶1∶0.7。调和n-3与n-6 PUFAs比例,直接添加亚麻酸等n-3 PUFAs类油脂纯品改善脂肪酸比例。     

蒙古斑点马不同部位脂肪和肌肉组织中脂肪酸组成的比较研究

通过对蒙古斑点马不同部位脂肪和肌肉组织中脂肪酸组成进行分析比较，旨在明确蒙古斑点马体脂脂肪酸组成特点。选择3 匹成年蒙古斑点马，屠宰后采集肾周、肠周和皮下脂肪以及肩肌、背最长肌和臀肌样品，利用气相色谱法测定脂肪酸组成及含量。结果表明：蒙古斑点马不同脂肪组织中均检出19 种脂肪酸，其中饱和脂肪酸（saturated fatty acid，SFA）含量34.77%～37.38%，不饱和脂肪酸（unsaturated fatty acid，UFA）含量达60%以上，UFA中单不饱和脂肪酸（monounsaturated fatty acid，MUFA）含量33.04%～36.39%，多不饱和脂肪酸（polyunsaturated fatty acid，PUFA）含量26.47%～27.51%，其中皮下脂肪C10:0、C18:0、C20:0含量显著低于肾周和肠周脂肪（P＜0.05）；MUFA在皮下脂肪的沉积程度较其他2 个部位高，但均无统计学差异；PUFA中C18:3 n-3含量最高，其在各脂肪组织间无显著差异。3 个不同部位肌肉中均检出15 种脂肪酸，其中SFA含量占总脂肪酸含量的38.32%～40.04%，MUFA含量占35.70%～40.19%，PUFA含量占15.25%～20.33%；SFA中背最长肌和臀肌C12:0含量显著高于肩肌（P＜0.05），其余SFA在不同部位肌肉间无显著差异；MUFA中背最长肌C16:1含量显著高于肩肌和臀肌（P＜0.05）；肩肌n-6/n-3 PUFA比值显著高于背最长肌和臀肌（P＜0.05）；皮下脂肪的C18:3 n-3和总PUFA含量显著高于背最长肌（P＜0.05）。综上所述，蒙古斑点马不同部位脂肪和肌肉组织脂肪酸组成各具特点，但UFA含量均较高。     

青海牦犊牛肉脂肪酸组成分析

分析青海牦犊牛与成年牦牛肌肉脂肪酸组成特点,将肌肉提取脂肪后进行甲酯化,以脂肪酸酯标样作为标准品,采用气相色谱仪对试样的脂肪酸甲酯进行定性与定量.结果显示,牦犊牛的MUFA、PUFA相对含量极显著高于成年牦牛(P<0.01).分别占到总量的32.38%和11.59%,其中油酸、亚油酸含量尤为突出,分别为29.52%、5.72%,而SFA相对含量为53.54%显著低于成年牦牛的61.04%(P<0.05).牦犊牛PUFA/SFA与n-6/n-3值分别为0.98%、0.22%均极显著高于成年牦牛(P<0.01).青海牦犊牛肉脂肪酸营养价值更高、更均衡,对牦犊牛的选育、肉品深加工具有一定意义.     

不同类型膳食脂肪酸对肥胖小鼠肝脏及其血液中脂肪酸组成和代谢相关基因影响

目的探讨不同类型膳食脂肪酸对肥胖小鼠肝脏及其血液中脂肪酸组成及代谢相关基因的影响。方法 8周龄雄性C57BL/6小鼠随机分为7组,即对照组(喂基础饲料)、长链饱和脂肪酸(LCSFA)组(喂猪油高脂饲料)、中链饱和脂肪酸(MCSFA)组(喂椰子油高脂饲料)、n-3多不饱和脂肪酸(n-3 PUFA)组(喂亚麻籽油高脂饲料)、n-6多不饱和脂肪酸(n-6 PUFA)组(喂大豆油高脂饲料)、单不饱和脂肪酸(MUFA)组(喂橄榄油高脂饲料)和反式脂肪酸(TFA)组(喂8%氢化大豆油高脂饲料),每组10只,共干预16周,所有种类饲料总能量均相同,基础饲料脂肪供能比为10%,各高脂饲料脂肪供能比均为45%,喂养周期结束后,禁食12 h,麻醉后立刻解剖取出肝脏。采用气相色谱法分析肝脏及其血液中脂肪酸组成的变化,实时荧光定量聚合酶链式反应(PCR)检测肝脏脂肪酸代谢相关基因的表达,肝脏脂质沉积采用油红O染色法检测。结果与对照组比较,LCSFA组、MCSFA组、n-6 PUFA组、MUFA组和TFA组小鼠肝脏中均出现明显的脂质沉积,n-3 PUFA组小鼠肝脏未出现明显的脂质沉积。与对照组比较,LCSFA组小鼠肝脏及血液中总n-6 PUFA和总PUFA含量升高; n-3 PUFA组小鼠肝脏及血液中总n-3 PUFA和总PUFA含量增加,但总MUFA含量减少; n-6 PUFA组小鼠肝脏及血液中总n-6PUFA、总n-3 PUFA和总PUFA含量升高,但总饱和脂肪酸(SFA)和总MUFA含量降低; MUFA组小鼠肝脏及血液中总SFA含量减少; TFA组小鼠肝脏及血液中C18∶1 n-9t(TFA)含量升高;以上差异均有统计学意义(P0. 05)。LCSFA组和MCSFA组小鼠肝脏脂肪酸代谢基因固醇调节元件结合蛋白1(SREBP-1c) mRNA水平高于对照组和n-6 PUFA组,差异均有统计学意义(P0. 05)。结论小鼠肝脏及其血液中脂肪酸构成与其对应的膳食脂肪酸模式一致。不同类型脂肪酸高脂饲料可通过对相关基因的表达影响肥胖状态下肝脏的脂质代谢及脂质沉积。     

低剂量γ辐照对牛肉肌内脂肪酸组成及牛肉质量的影响

取8头黄牛的半腱肌,在60Co源下辐照,剂量分别1.13,2.09及3.17kGy,牛肉在7℃环境下储存10d,评估不同辐照剂量和储存时间(0d或10d)条件下肌内脂肪酸组成及牛肉质量的变化.肉样储存10d后,未辐照的肉样中SFA和MUFA含量比未储存未辐照的牛肉(0d,0kGy)显著上升,而辐照过的肉样SFA和MUFA含量基本不变.辐照后多不饱和脂肪酸(PUFA)、n-3PUFA、n-6PUFA含量和P/S显著下降(0d或10d).不同辐照剂量对脂肪酸的影响差异不显著.辐照后0d,牛肉样滴水损失及TBARS与辐照剂量呈正相关,随着辐照剂量的增加(从0kGy到3.17kGy),滴水损失及TBARS逐步升高;而10d储存后,滴水损失和TBARS则与辐照剂量呈负相关.辐照后牛肉样细菌总数随辐照剂量的增大显著下降.牛肉肌内脂肪脂肪酸组成和比值因辐照而产生变化,而辐照剂量的增加(1.13kGy到3.17kGy)对脂肪酸组成没有显著的影响.3kGy左右的低剂量辐照可以很好的确保牛肉质量,而不会引起脂肪营养较大的损失.     

核桃调和油在不同烹饪温度下氧化稳定性的变化

为保持核桃油热加工过程中营养和热稳定性,将核桃油与亚麻籽油、花生油、红花籽油和菜籽油进行调和,根据中国营养学会推荐脂肪酸摄入量,利用数学模型计算出核桃调和油中各原料所占比例,研制出核桃油含量分别为1%、5%、15%、25%的营养均衡核桃调和油。分析中式烹饪温度下核桃调和油的过氧化值、茴香胺值和总氧化值及品质变化和脂肪酸含量的变化。结果表明,4种调和油饱和脂肪酸（SFA）、单不饱和脂肪酸（MUFA）和多不饱和脂肪酸（PUFA）的质量分数比例接近0.27:1:1,n-6/n-3脂肪酸均在（4~6）:1推荐值范围之内,符合人体对脂肪酸均衡摄入的需求。1%、5%、15%、25%的调和油过氧化值、茴香胺值和总氧化值随加热温度升高而升高,210 ℃时PUFA/SFA比值分别为0.30%、0.39%、0.70%、0.96%,MUFA/PUFA比值较纯核桃油分别增加0.03%、0.07%、0.11%、0.14%,n-6/n-3脂肪酸比例介于4.42~5.76之间过氧化值、茴香胺值及总氧化值均低于纯核桃油,表明纯核桃油经过调和,有助于减缓氧化物的生成,提高热稳定性,维持脂肪酸的膳食平衡。     

不同处理后的四川白兔肌内脂肪酸组成在冷藏过程中的变化

研究了用4种不同的处理方式(微波、烘烤、蒸煮、和超声波辅助腌制)对四川白兔的后腿肌(hind leg muscle,HL)进行处理后再用2种不同包装方式进行包装(非真空和真空包装),分析样品在冷藏过程中肌内总脂肪含量及脂肪酸组成的变化。结果表明,四川白兔肌内脂肪主要含20种脂肪酸,多数为不饱和脂肪酸。在0~12 d的冷藏过程中,4种方式处理后的四川白兔肌内脂肪含量显著下降(P0.05)。相对其他处理方式来说,微波处理对不饱和脂肪酸(UFA)尤其是多不饱和脂肪酸(PUFA)的影响较小,而蒸煮对PUFA破坏作用最大。随冷藏时间的延长,饱和脂肪酸(saturated fatty acid,SFA)的含量升高显著(P0.05),UFA、PUFA含量与P/S(PUFA/SFA)、n-6/n-3(n-6系列PUFA/n-3系列PUFA)的比值显著降低(P0.05),而单不饱和脂肪酸(MUFA)含量变化不显著。从脂肪氧化角度来看,处理后兔肉中丙二醛(MDA)的沉积量在0~10 d冷藏期间内不断升高,且耐贮性不断降低。真空包装的样品在饱和脂肪酸(saturated fatty acid,SFA)上升与UFA下降的趋势方面有减缓作用,同时将TBA值维持在较低的水平,延缓了加工肉品的腐败变质。     

驼、牛、羊乳中脂肪酸含量的比较分析

采用气相色谱法对驼、牛、羊乳3 种乳中脂肪酸（fatty acids,FA）种类及含量进行比较。结果表明,3 种乳脂肪酸种类和含量差异显著。驼乳检测出33 种脂肪酸,棕榈酸相对含量最高（（23.73±2.17）%）;驼乳的多不饱和脂肪酸（polyunsaturated fatty acids,PUFA）相对含量（（4.09±0.54）%）显著高于牛乳和羊乳;牛乳中检测出29 种脂肪酸,棕榈酸相对含量最高（（27.44±2.45）%）;羊乳检测出34 种脂肪酸,且油酸相对含量最高（（30.89±3.57）%）。3 种乳中羊乳单不饱和脂肪酸（monounsaturated fatty acids,MUFA）含量最高（（35.26±3.86）%）。此外,结合主成分分析和相关性分析方法,对驼乳的脂肪酸含量进行进一步分析,结果显示,驼乳的饱和脂肪酸（saturated fatty acids,SFA）∶MUFA∶PUFA为1∶0.60∶0.08,驼乳更接近联合国粮食及农业组织/世界卫生组织推荐SFA∶MUFA∶PUFA为1∶1∶1。PUFA与短链脂肪酸（short-chain fatty acids,SCFA）、长链脂肪酸（long-chain fatty acids,LCFA）呈负相关,与n-6 FA相关性最大（0.978）;SCFA与LCFA呈正相关,n-6 FA与n-3 FA呈正相关。     

库尔勒香梨表皮蜡质化学组分的变化与其贮藏品质的关系

以库尔勒香梨为实验材料,研究其在常温和冷藏过程中表皮蜡质含量和主要化学组分的变化及其与贮藏品 质的关系。通过气相色谱-质谱联用技术分析蜡质主要成分的变化,并测定贮藏期间果实质量损失率、腐烂率、硬 度、可溶性固形物质量分数、可滴定酸质量分数与总酚质量浓度等与贮藏品质相关的指标,将蜡质含量、主要组分与 贮藏品质进行相关性分析。结果表明：与常温贮藏相比,采后冷藏抑制了库尔勒香梨贮藏前期蜡质含量的增加和后期 的减少;常温和低温贮藏期间,烷烃、脂肪酸和烯烃相对含量较高,醇、醛和酯类物质次之,随着贮藏时间的延长, 烷烃相对含量先增加后减少,脂肪酸与烯烃相对含量逐渐增加,而醇、醛和对照组酯类相对含量均呈下降趋势,但冷 藏明显抑制了蜡质中脂肪酸、烯烃和贮藏前期烷烃相对含量的增加,以及醛类和贮藏后期烷烃相对含量的下降,且对 醇和酯类物质抑制效果不明显;常温和冷藏组蜡质含量、烯烃和脂肪酸含量均与质量损失率、腐烂率、硬度、可溶性 固形物和可滴定酸质量分数极显著相关（P＜0.01）,蜡质含量与总酚质量浓度极显著相关（P＜0.01）。常温组酯类 相对含量与各指标均无显著相关性,而冷藏组酯类含量与各指标均显著或极显著相关（P＜0.05,P＜0.01）。     

不同杀菌温度及贮藏条件对卤蛋菌落总数和脂肪酸组分的影响

本实验以真空包装卤蛋为研究对象,进行95、105 ℃和121 ℃不同温度杀菌,并分别于4 ℃和25 ℃下进行贮藏（121 ℃杀菌仅在25 ℃下贮藏）,测定并分析各样品在贮藏期间内菌落总数和脂肪酸组成的变化。结果表明：各杀菌温度都可在杀菌完成时有效杀灭活体细菌,各组样品菌落总数均小于10 CFU/g;相较于95 ℃杀菌样品,105 ℃和121 ℃杀菌样品的多不饱和脂肪酸总含量分别下降了1.56%和6.83%;随着贮藏时间延长,受杀菌温度、贮存温度、微生物种类、微生物增殖及氧化水解反应等因素的影响,各组样品脂肪酸组成发生差异性变化。95 ℃杀菌、25 ℃贮存的样品仅可保存15 d,且脂肪酸劣变速率最快;105 ℃杀菌、25 ℃贮存的样品可保存75 d,脂肪酸劣变速率较慢;95 ℃杀菌、4 ℃贮存的样品可保存90 d,但脂肪酸劣变速率较快;121 ℃杀菌、25 ℃贮存的样品贮藏90 d时仍未检测到微生物增殖,贮藏期间内脂肪酸总量保留较好,但初始多不饱和脂肪酸水平较低;105 ℃杀菌结合4 ℃贮存的样品在贮藏90 d时同样未检测到微生物增殖,且贮藏期内总脂肪酸保存率最高,可作为生产高营养水平和长保质期卤蛋较好的应用技术。     

牦牛酥油贮藏期间脂肪酸和健康评估指数变化

该研究通过测定青藏高原牦牛酥油脂肪酸情况,计算动脉粥样硬化指数(atherogenic index, AI)、血栓形成指数(thrombopoiesis index, TI)、促健康指数(health promotion index, HPI)和低胆固醇血症/高胆固醇血症比率(hypocholesterolemia/hypercholesterolemia ratio, HH)4个健康指数,探索和揭示贮藏期间牦牛酥油脂肪酸的组成特征、功能活性脂肪酸及健康指数变化。采用青海省海北藏族自治州和甘肃甘南藏族自治州的牦牛酥油,在4℃下贮藏0、1、2、3、4、5个月,利用GC-MS进行脂肪酸分析。结果显示,在整个贮藏期内牦牛酥油中棕榈酸、油酸、硬脂酸为优势脂肪酸,海北和甘南酥油多不饱和脂肪酸(polyunsaturated fatty acids, PUFA)相对含量分别为5.99%～4.62%和7.77%～6.60%;单不饱和脂肪酸(monounsaturated fatty acids, MUFA)含量分别为28.61%～26.42%和29.51%～26.95%;甘南酥油奇数碳链脂肪酸(od...     

CHANGES IN MOLECULAR SPECIES COMPOSITIONS OF GLYCEROPHOSPHOLIPIDS IN THE ADDUCTOR MUSCLE OF THE GIANT EZO SCALLOP PATINOPECTEN YESSOENSIS DURING FROZEN STORAGE

Changes in lipid components, particularly glycerophospholipids, in the adducto; muscle of giant ezo scallop during storage at −20C were investigated. During storage, the contents of total lipids (TL) and polar lipids (PL) decreased, but that of nonpolar lipids increased. Thiobarbituric acid reactive substances and peroxide values of the TL increased with duration of storage. Glycerylphosphorylcholine (GPC) and glycerylphosphrylethanolamine (GPE) decomposed considerably during storage, and decreased by 50% and 15% of the initial content, while lyso-PC (LPC) and free fatty acids (FFA) increased, respectively. The percentages of polyunsaturated fatty acids (PUFAs) such as 20:5n-3 and 22:6n-3 in the TL and PL during storage decreased, however, those of the PUPAs in the NL increased. Diacylglycerylphosphorylcholine (diacyl-GPC) and diacylglycerylophosphorylethanolamine (diacyl-GPE), major components in the GPC and GPE subclasses, showed a marked decrease with duration of storage. Particularly, diacyl-GPC decreased by 68% of the initial contents of the PL. In the alkenylacyl-GPE and diacyl-GPC, the percentages of the molecular species having longer hydrocarbon chains on the sn-l positions of glycerol moieties decreased at     

冷藏期间不同加工处理后伊拉兔肉中肌内总脂肪含量的变化

以伊拉兔背部最长肌为原料,用3 种不同的加工方式（蒸煮、微波和锡箔烘烤）对其进行处理,观察各样品在冷藏期间肌内总脂肪含量及脂肪酸组成的变化。在0～9 d冷藏期间,蒸煮、微波和烘烤3 种加工处理后的样品肌内脂肪的干质量比例均有显著下降（P＜0.05）,尤其是6～9 d冷藏后期。相对而言,微波处理对不饱和脂肪酸（unsaturated fatty acids,UFA）的破坏作用较小,且该处理后的伊拉兔肉样品在冷藏期间肌内脂肪含量较高。在整个冷藏期间,伊拉兔肌内总脂肪酸中,饱和脂肪酸和单不饱和脂肪酸的比例均显著升高（P＜0.05）,而多不饱和脂肪酸（polyunsaturated fatty acids,PUFA）的比例均显著降低（P＜0.05）,其中6～9 d期间各样品中PUFA比例（尤其是长链PUFA）下降幅度最大。总体来讲,微波处理后的样品较之蒸煮和锡箔烘烤处理后的样品在冷藏期间具有更高的UFA。经偏最小二乘回归法分析,微波处理较之蒸煮和烘烤能够保留样品冷藏期间肌内总脂肪酸的组成,而锡箔烘烤处理后的样品较不利于冷藏。此外,处理后样品中的丙二醛沉积量在0～9 d期间持续升高,且耐贮性会大大降低,其中6～9 d冷藏期间的硫代巴比妥酸反应物质增幅较快。     

Effect of frozen storage on lipids and lipolytic activities in the longissimus dorsi muscle of the pig

 Samples of longissimus dorsi muscle from pigs were vacuum-packed and stored at –18  °C for a 6-month period. The quantity of total lipids, non-polar lipids, phospholipids and cholesterol remained unchanged during storage. However, there was a decrease (1.4%) in the polyunsaturated fatty acid percentage of the phospholipid fraction after 6 months of frozen storage, mainly due to the decrease in linoleic fatty acid. Nevertheless, there was no change in fatty acid composition of the non-polar lipid fraction. Phosphatidylethanolamine was the phospholipid most affected during the frozen storage, with a significant decrease from an intial percentage of 26.6% to 23.0% after 6 months of storage. Important activities of muscle lipolytic enzymes were still recovered after the storage, which explains the continuous release of free fatty acids reported during the process, with a net increase of 50.6 mg/100 g dry matter. The highest release of free fatty acids was reported during the 1st month of frozen storage. At the 6th month of frozen storage the compositions of both the free fatty acid and phospholipid fractions were similar. With respect to oxidation, the thiobarbituric acid test number showed a slight increase during the process while the peroxide value remained unchanged. Received: 16 March 1998 / Revised version: 17 June 1998     

Effect of frozen storage on lipids and lipolytic activities in the longissimus dorsi muscle of the pig

 Samples of longissimus dorsi muscle from pigs were vacuum-packed and stored at –18  °C for a 6-month period. The quantity of total lipids, non-polar lipids, phospholipids and cholesterol remained unchanged during storage. However, there was a decrease (1.4%) in the polyunsaturated fatty acid percentage of the phospholipid fraction after 6 months of frozen storage, mainly due to the decrease in linoleic fatty acid. Nevertheless, there was no change in fatty acid composition of the non-polar lipid fraction. Phosphatidylethanolamine was the phospholipid most affected during the frozen storage, with a significant decrease from an intial percentage of 26.6% to 23.0% after 6 months of storage. Important activities of muscle lipolytic enzymes were still recovered after the storage, which explains the continuous release of free fatty acids reported during the process, with a net increase of 50.6 mg/100 g dry matter. The highest release of free fatty acids was reported during the 1st month of frozen storage. At the 6th month of frozen storage the compositions of both the free fatty acid and phospholipid fractions were similar. With respect to oxidation, the thiobarbituric acid test number showed a slight increase during the process while the peroxide value remained unchanged.     

Oxidative stability of buttermilk as influenced by the fatty acid composition of cows' milk manipulated by diet

Milk from cows fed a low-fat diet high in cereals designed to stimulate fat synthesis de novo was lower in unsaturated fatty acids (21.3%) than milk from cows fed a diet high in fat, mainly from roasted soy beans (41.3% unsaturated fatty acids). Buttermilk from the more unsaturated milk was less oxidatively stable during storage (at 4 degrees C, followed for 11 d) than buttermilk from the more saturated milk, as monitored both by primary lipid oxidation products (lipid hydroperoxides) and by the secondary lipid oxidation product, hexanal. Fat-soluble antioxidants, beta-carotene and alpha-tocopherol, analysed by HPLC, were not consumed during storage for either of the two types of buttermilk. In contrast, the antioxidative capacity of the serum phase decreased during storage as evaluated in a radical scavenging assay based on the semi-stable water-soluble radical nitrosodisulphonate (Fremy's salt). The time course for the decrease in water-soluble antioxidants was very similar for the two types of buttermilk suggesting that oxidation is initiated in the serum phase independently of fatty acid composition.     

Lipids and fatty acids of a whitefish (Coregonus albula) flesh and roe

The total lipids of whitefish flesh and roe averaged 3.0 and 9.8% fresh weight, respectively. Although neutral lipids dominated in both tissues the polar lipid content of fresh roe was unexceptionally high (2.5%). The fatty acid patterns of the total lipids from flesh and roe and of neutral lipids were similar to each other. Polyenoic acids constituted about half of the total fatty acids and monoenoic and saturated components existed in equal amounts. The calculated iodine values for the total lipids from flesh and roe indicated a slightly higher degree of unsaturation for roe fatty acids. The polar lipids were enriched in polyenoic and saturated fatty acids. Similarities in the composition and content of fatty acids from flesh and roe suggest that storage problems, apparent as a rancidity of roe products, may result from the high content of polar lipids readily hydrolysed during storage.     

Changes in Lipid Composition of Sweet Potatoes as Affected by Controlled Storage

SUMMARY— The fatty acid composition of the lipids extracted from Georgia Red and Centennial varieties of sweet potatoes was studied to determine changes during storage at 15.5, 10, and 4.5°C. The two varieties did not differ initially in the relative proportions of fatty acids. However, changes in fatty acid composition were noted during storage and appeared to be mere pronounced at low storage temperatures. The most consistent changes noted were an increase in tetra-cosaenoic acid and a decrease in short chain saturated acids. The Centennial variety contained higher levels of total lipids, which were generally reflected in higher levels of the three fractions, (1) non-phospholipids, (2) cephalin and (3) lecithin. The increase in total lipids and the individual lipid fractions with storage is indicative of two processes that may have occurred in the stored roots. The lipids may have become more extractable as the respiring potato underwent compositional changes, or lipids were being synthesized from non-lipid components. Although changes observed in the relative proportions of fatty acids during storage at different temperatures were not always consistent, the possibility is suggested that changes in fatty acid composition may be related to changes in quality of the potato during storage.