辐照糙米储藏过程中淀粉脂和非淀粉脂组成及变化

目的：研究低剂量60Co-γ辐照对储藏糙米的淀粉脂和非淀粉脂的粗脂肪含量和脂肪酸组成的影响,为辐照糙米储藏提供数据支持和理论依据。方法：晚粳米收获后进行60Co-γ辐照,设0.2、0.5、1.0 kGy和2.0 kGy 4 个不同的辐照剂量水平,之后恒温（15±0.5）℃储藏12 个月,每3 个月进行一次品质测量。结果：辐照糙米在储藏12 个月的过程中,非淀粉脂含量变化不显著（P＞0.05）,淀粉脂含量在储藏过程中持续下降,储藏12 个月后,淀粉脂含量显著降低（P＜0.05）。在储藏过程中,非淀粉脂和淀粉脂的各个脂肪酸组成的含量表现出不同的增加或减少趋势。在同一时期,辐照糙米和未辐照糙米的粗脂肪（淀粉脂和非淀粉脂）含量没有显著差异（P＞0.05）,说明辐照不会影响粗脂肪含量,辐照对各糙米的脂肪酸组成没有显著的影响。结论：低剂量的辐照处理不会改变储藏过程糙米的脂类组成,储藏对糙米的淀粉脂和非淀粉脂有不同的影响。     

温度和壳寡糖对海胆贮藏品质的影响

研究温度和壳寡糖质量浓度对马粪海胆(Hemicentrous pulcherrimus)冷藏过程中品质变化的影响4℃和0℃条件的贮藏特性,并采用4种不同质量壳寡糖对马粪海胆进行处理,以感官评定、细菌总数、挥发性盐基氮(totalvolatile basic nitrogen,TVB-N)、pH值为指标,对其贮藏过程中的品质变化进行测定。结果表明:与4℃相比,0℃条件各项指标均较低(P<0.05),将该温度条件与壳寡糖处理复合后,保鲜效果明显增强(P<0.05),但不同壳寡糖质量组之间的各项指标差异不大(P>0.05),与4℃对照相比,0.1g/100mL壳寡糖质量浓度浸泡处理后冰温贮藏可延长货架期5～6d。     

茶多酚对草鱼冷藏过程脂肪酸的影响

采用GC-MS法研究草鱼鱼肉脂肪酸的组成及茶多酚对鱼肉脂肪酸变化的影响.测定在4℃贮藏条件下,添加不同含量茶多酚的鱼肉中各脂肪酸的相对含量.结果表明:草鱼鱼肉中含有18种脂肪酸,其中饱和脂肪酸占29.29％,不饱和脂肪酸占70.68％;在4℃贮藏过程中,荼多酚对脂肪酸有明显的保护作用,添加了茶多酚的试验组中各脂肪酸含量都明显高于空白组,综合分析确定:茶多酚添加量为0.03％效果最佳.     

鲍鱼预熟制及低温贮藏中的脂质氧化特性

为探究鲍鱼在不同预处理和贮藏条件下的品质变化,研究不同预熟制工艺和低温贮藏条件对其腹足脂质变化的影响。通过水蒸气蒸馏法、气相色谱-质谱联用仪检测硫代巴比妥酸反应物(thiobarbituric acid reactive substances,TBARS)值和脂肪酸组成。结果表明,新鲜鲍鱼样品的TBARS值为1.01 mg/kg,经4℃贮藏4 d、-18℃贮藏35 d、-80℃贮藏35 d后分别为4.12、4.31、3.40 mg/kg。而经80℃加热2 h预熟制处理鲍鱼的TBARS值为1.90 mg/kg,其在4℃贮藏4 d、-18℃贮藏35 d、-80℃贮藏35 d后分别为1.91、1.86、1.91 mg/kg,在贮藏过程中无明显变化。经预熟制处理的鲍鱼在-18℃冻藏21 d后的二十碳五烯酸和二十二碳五烯酸含量分别为9.78%和5.32%,明显高于直接冻藏(分别为8.76%和5.01%)的鲍鱼。因此,认为新鲜鲍鱼的脂质氧化主要发生在冻藏阶段,而预熟制工艺可以有效延缓冻藏过程中脂质氧化的发生。     

Characterization of the Lipid Fraction of Wild Sea Urchin from the Sardinian Sea (Western Mediterranean)

The fatty acid (FA) composition of Spatangus purpureus, Echinus melo, Sphaerechinus granularis, and Paracentrotus lividus, sea urchins, has been studied. Sea urchins were collected at different depth along Sardinia coast in the Mediterranean sea, and their gonad was measured, separated, and analyzed for FA composition by gas chromatography‐mass spectrometry. A total of 53 FAs were detected, 16 saturated (SFA), 10 monounsaturated (MUFA), 9 polyunsaturated (PUFA), and 13 highly unsaturated (HUFA). Moreover, 5 furan FAs (FFAs) were revealed for the first time in sea urchin. The HUFA and PUFA classes were the most represented accounting for almost 80% of total FAs. Among these compounds, C20:4 n6 (19.64, 20.52, 23.37, and 8.48 mg/g, respectively) and C22:6 n3 (19.68, 20.05, 3.83, and 1.78 mg/g, respectively) were the most abundant. The results of principal component analysis indicated that the sea urchin samples could be clearly discriminated with respect to their FAs composition.     

鳗鱼鲞冷藏过程中油脂氧化及挥发性物质的变化

为研究家庭冷藏条件下鳗鱼鲞油脂氧化和风味衰减情况,将成熟鳗鱼鲞在1～7℃(模拟家庭冰箱)冷藏4个月,测定其在冷藏期内过氧化值(peroxide value,POV)、硫代巴比妥酸(thiobarbituric acid,TBA)值和脂肪酸、风味成分的组成及相对含量变化并结合相关性分析研究冷藏期内鳗鱼鲞油脂和风味物质变化...     

鸡蛋高温贮藏下脂质变化及酶活相关性研究

本研究通过考察鸡蛋高温贮藏(37℃)条件下脂质组分变化、脂肪酶活性变化及氧化指标的变化,并借助相关性分析阐释酶活变化与脂质氧化的内在联系。实验结果表明:贮藏过程中鸡蛋失重率、蛋黄p H、蛋黄水分含量显著增加而蛋黄指数和哈弗单位(HU)显著下降(p0.05);37℃贮藏15 d后,总脂质含量由于水分迁移而呈现下降趋势(从28.93 g/100 g降至24.20 g/100 g),磷脂含量显著降低(45.55 g/100 g降至34.37 g/100 g脂质)而游离脂肪酸显著增加(1.24 g/100 g增至3.67 g/100 g脂质),与脂质变化相关的中性脂肪酶、酸性脂肪酶及磷脂酶至贮藏结束活力分别下降76.50%、56.78%、56.81%。磷脂组分中的磷脂酰胆碱(Phosphatidylcholine,PC)、磷脂酰乙醇胺(Phosphatidyl ethanolamine,PE)、磷脂酰肌醇(Phosphatidylinositol,PI)在贮藏过程中也呈现含量显著下降的趋势而过氧化值(Peroxide value,POV)、硫代巴比妥酸值(Thiobarbituric Acid Reactive Substances,TBARS)呈现显著升高。相关性分析证明脂质组分变化与酶活变化显著相关。本研究说明鸡蛋贮藏中脂质会发生明显的水解及氧化,这些变化在一定程度上由酶促氧化造成。     

低温贮藏条件下阿勒泰羊尾的脂肪氧化

以阿勒泰羊尾脂肪为研究对象,研究其在(4±1)℃条件下贮藏脂肪的动态变化趋势。结果表明:贮藏期0~25 d为阿勒泰羊尾脂肪的氧化初期,在此期间,p H值呈现持续性下降的趋势(P0.05),过氧化值在阿勒泰羊尾脂肪贮藏第25天出现最大值随后呈现逐渐下降的趋势(P0.05);硫代巴比妥酸反应物值在贮藏期间,呈现非常显著的递增趋势(P0.05);饱和脂肪酸含量由43.6%提高至56.3%,单不饱和脂肪酸和多不饱和脂肪酸分别由2.4%和51.2%下降至2.1%和43.7%;此外,功能性脂肪酸除了共轭亚油酸(C_(18:2n-9))之外,其他均在贮藏期第20天后下降显著(P0.05)。     

Lipid Peroxidation and Chemical Changes in Catfish (lctalurus puncfatus) Muscle Microsomes during Frozen Storage

An NADH-dependent lipid peroxidation system previously identified in channel catfish muscle microsomes functioned at ?10° in isolated microsomes. Below that, activity was inhibited. The amount of peroxidase activity remaining after thawing previously frozen isolated microsomes or intact catfish fillets was inversely related to storage temperature. Microsome yield and lipid content were lower in the fillets stored at - 10° than -40°. Most microsomal fatty acids, especially PUFAs, gradually decreased in the fish fillets stored at -10°. Prolonged storage of catfish fillets would require storage below -20°. Any thawing would result in reactivation of the peroxidase system.     

水煮牛肉冷藏期间脂质和蛋白质氧化与质构特性变化

水煮处理后的牛肉条4 ℃冷藏0~5 d,探讨冷藏期间牛肉中血红素铁含量与脂质和蛋白质氧化之间的关系,以及氧化对肉品质构的影响。结果表明,随着水煮牛肉冷藏时间的延长,与0 d血红素铁含量相比,5 d时血红素铁含量显著降低(p<0.05);而5 d时非血红素铁含量相比0 d时显著升高(p<0.05);5 d时水煮牛肉的硫代巴比妥酸(TBARS)值和蛋白羰基值是0 d含量的19倍和2.67倍;游离巯基含量随着冷藏天数的增加显著降低(p<0.05);剪切力、硬度、胶粘性、咀嚼性等数值在冷藏期间均显著升高(p<0.05)。综上所述,经过水浴加热的牛肉冷藏初期血红素铁含量较高,促进TBARS值在0~1 d阶段迅速上升,冷藏后期非血红素铁含量和TBARS值升高,其促进蛋白氧化进程,水煮牛肉剪切力和硬度等数值显著上升(p<0.05)。     

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.     

冻藏过程中鱼类脂肪氧化的研究现状

鱼类富含不饱和脂肪酸,在冻藏期间鱼体易发生脂肪氧化,尤其是多脂鱼类。脂肪氧化不仅可缩短保存期,还可引起鱼肉质地、风味变差。为延长保存期,提高鱼肉品质,研究者对脂肪氧化开展了诸多研究。本文即对冻藏期间脂肪氧化的影响因素、氧化机理、控制及氧化程度的评定等方面的研究现状作一综述。     

猪肉-鱼肉复合狮子头贮藏期间的品质变化规律

为明确猪肉-鱼肉复合狮子头的最佳贮藏方式及贮藏期限,以猪肉和鱼肉为主要原料,采用一次加热成型工艺制备猪肉-鱼肉复合狮子头,研究复合狮子头在冷藏(4℃)和冻藏(-18℃)期间的色度、质构特性、pH值、菌落总数、硫代巴比妥酸反应物(thiobarbituric acid reactive substances,TBARs)值、总挥发性盐基氮(total volatile basic nitrogen,TVB-N)含量及感官品质的变化规律。结果表明:在整个贮藏期间,复合狮子头的亮度值、白度值、硬度和感官评分随贮藏时间的延长而显著降低(P<0.05);pH值呈先升高后降低的趋势;TBARs值、TVB-N含量显著升高(P<0.05),产品在4℃贮藏15 d后,TBARs值超过2 mg/kg,且硬度、内聚性和感官评分均在贮藏15 d后显著下降(P<0.05),较初始值分别下降16.29%、12.20%和31.11%;复合狮子头在-18℃贮藏60 d期间菌落总数均低于国家限量要求,TBARs值和TVB-N含量均在规定限量范围内,产品在-18℃冻藏60 d时仍表现出良好的品质特性。综...     

玉米储藏过程中挥发性成分变化研究

为了研究玉米储藏期间气味变化情况,采用优化的顶空固相微萃取-气质联用法(HS-SPME-GC-MS)分析玉米在常温(25℃)密闭储藏过程中的主要挥发性成分组成。检出的物质主要包括烃类、醛类、酯类、醇类、酮类、酸类和少量杂类物质。结果表明,在储藏过程中烃类物质总相对含量在储藏末期比储藏初期有所增加。酸类物质相对含量呈缓慢上升但含量较低。酮类物质相对含量较低且呈逐渐降低趋势。醇类挥发性成分在储藏120 d前呈现增加趋势,在120 d后有所降低。醛类和酯类物质相对含量呈现先升高后降低,二者相对含量较高,储藏180 d后的相对含量接近于0 d,是玉米风味的主要贡献物质。而烃类和醇类风味阈值较高,不是玉米储藏期间风味的主要贡献物质。25℃下密闭储藏180 d后的玉米其气味与储藏0 d的玉米相比,并未发生人嗅觉可感知的明显异味变化。     

Changes in Soya Bean Lipid Profiles during Kinema Production

The influence of processing on soya bean lipids during kinema production was studied. The crude lipid (CL), free fatty acid (FFA) and phytosterol contents of raw beans were 121 g, 6·9 g and 0·8 g kg⁻¹ dry matter, respectively. After soaking and cooking the moisture content of beans increased significantly from 121 to 749 g kg⁻¹, whilst the lipid contents were unchanged. During a 2 day fermentation at 37°C, the lipid contents increased significantly as indicated by capillary column gas chromatography (GC) analysis of petroleum ether extracts of lyophilised samples of unfermented and fermented beans. The fatty acids, palmitic (C16:0), stearic (C18:0), oleic (C18:1), linoleic (C18:2), linolenic (C18:3) and arachidic (C20:0) acids were identified. The major fatty acid present in all samples was the essential fatty acid, linoleic acid. All of the aforementioned fatty acids (except arachidic) were liberated during fermentation by microbial lipases, yielding approximately the same proportion of fatty acids found in unfermented beans. The unsaponifiable soya bean lipids identified by GC were campesterol, stigmasterol and β-sitosterol (ratio 1·2:1:3·4). Levels of these increased during fermentation by 50–61%, but remained in approximately the same proportions.     

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.     

浓香型白酒在陈酿过程中的酒质变化

对白酒的感官指标、酒精度、理化指标（总酸、总酯）、卫生指标（甲醇、杂醇油）、固形物含量、色谱骨架指标、pH值、电导率等在陈酿过程中的变化趋势进行研究。结果表明,不同的酒体在陈酿过程中,质量（口感）都会有很大的改善,浓香型大曲原酒（原度）经过8个月陈酿之后各项指标最终形成一种动态平衡,口感更加绵柔,醇厚;浓香型大曲降度酒（45度）以及42度浓香型成品酒指标变化规律性不强,质量（口感）在陈酿3-4个月后,协调性、缔合性达到最佳效果;陈酿时间过长,新型白酒易产生水味,香料与酒精易分离;陶缸陈酿效果优于不锈钢大罐陈酿。     

包装猪肉贮藏过程中品质变化分析

以新鲜猪肉为研究对象,采用普通包装和真空包装两种方式进行包装,并于25℃条件下贮藏,重点研究包装猪肉在贮藏过程中的品质与肉中H2S含量、包装顶空H2S含量之间的变化关系。结果表明,随着贮藏时间的延长,包装猪肉的TVB-N值、菌落总数、普通包装顶空CO2含量均不断增大。并随着TVB-N的增加,包装猪肉中的含巯基(-SH)化合物含量增大,含巯基(-SH)的氨基在微生物的作用下,又进一步产生H2S,肉中H2S含量超过一定量时又迅速并扩散到包装顶空。使肉中的H2S含量降低,顶空H2S含量升高。     

用臭氧漂洗处理的鱼糜在贮藏过程中的品质变化

该研究探讨了用清水+臭氧水漂洗的鱼糜在-18℃贮藏期间凝胶强度、持水性、色泽、羰基、巯基、硫代巴比妥酸（TBA）、风味等的变化。研究得出,在0～24周贮藏期间,臭氧漂洗组羰基含量增加了4倍,TBA含量增加了约2倍,总巯基与游离巯基含量分别下降至原来的63.50%、66.61%。且相同贮藏时间臭氧漂洗组的羰基含量较对照组高,巯基含量较对照组低。随着贮藏时间的延长,臭氧漂洗组和对照组的鱼糜及鱼糜凝胶亮度与白度增大,凝胶持水性和凝胶强度缓慢下降,但前3周臭氧漂洗组的凝胶强度强于对照组。贮藏中鱼糜的腥味、鲜味和咸味降低。综上,在贮藏中臭氧漂洗虽然会一定程度上促进蛋白质与脂质的氧化,不过在贮藏终点时与对照组无显著性差异,而且清水+臭氧水漂洗可以在贮藏前一个月控制鱼糜凝胶强度的下降并一定程度上提高鱼糜白度。另外,一级动力学模型在贮藏前一个月可较好地反应其品质变化。该研究为臭氧在鱼糜贮藏稳定性上的应用提供了参考。