Effects of storage conditions on oxidative stability of soybean oil

Soybean oil in the presence or absence of 200 µg g^?1 tert‐butyl hydroquinone (TBHQ) was subjected to accelerated oxidative storage at 60 °C for 10 days or stored at room temperature for 12 months. Tocopherol contents of the oil decreased, whereas the headspace volatiles and peroxide values (PV) increased as the storage time increased. During accelerated storage, TBHQ was effective in retarding the formation of hydroperoxides and headspace volatiles in the oil. TBHQ also protected tocopherols, especially α‐tocopherol, from oxidation. During long‐term room‐temperature (LTRT) storage, the changes in PV between the oils with and without TBHQ were similar, but the oil with TBHQ had lower headspace volatile contents than that without TBHQ. Headspace volatile analysis was more suitable than PV measurement for predicting the oxidative stability of soybean oil during LTRT storage. The contents of hexanal or (E)‐2‐heptenal in the oil at 1–5 days of accelerated storage could be used to predict those of the corresponding compound in the oil at 0–4 weeks of LTRT storage. Copyright © 2005 Society of Chemical Industry     

不同包装材料和密闭储藏处理对油菜籽品质的影响

采用阻隔性能不同的编织袋、聚乙烯膜袋、复合膜袋和铝箔膜袋密闭储藏油菜籽,并分别进行不同处理(干燥储藏剂、二氧化碳充气、脱氧剂),研究不同处理方式对油菜籽主要品质酸价和过氧化值的影响。结果表明:油菜籽品质和包装材料的透氧率、透水率关系密切,铝箔膜袋和复合膜袋是比较理想的密闭储藏包装材料;干燥储藏剂的使用能显著提高储藏期种子发芽率,但对酸价和过氧化值无显著影响;对比不同密闭储藏处理方式,脱氧剂处理油菜籽品质保持最好,二氧化碳次之。研究获得了适合油菜籽密闭储藏的方式和包装材料,为油菜产区油菜籽的长期储藏提供了有效的技术和方法,也为其他富含油脂蛋白原料的储藏提供参考。     

不同贮存条件和包装材料对小包装食用油质量的影响

选用一级大豆油为原料,分析了3种包装材料和3种贮存条件对食用油质量的影响,结果表明:采用透明聚酯材料(PET)包装的食用植物油在阳光直射和灯光照射环境下,酸值和过氧化值变化最大,最佳的贮存条件应为避光保存.     

Effects of raw materials,processing conditions and packaging on the quality of plantain chips

The effects of raw material, processing conditions and packaging on the quality of plantain chips were investigated. Two cultivars of plantain Musa spp—Agbagba and Obino lewai—as well as cooking banana were used for the study. The fruits were at stages 1 to 4 of the banana ripening chart. The study started with a consumer survey aimed at product definition. This was followed by series of experiments to determine the effects of raw material, processing conditions and packaging on the quality of plantain chips. A correlation analysis was also carried out on the physical and chemical characteristics of raw plantain. The work revealed that the stage of ripeness of raw material had some effect on the quality of chips as there was gradual increase in pulp/peel ratio and sugar was significantly different (P < 0·05). Moisture content of pulp/texture of pulp, texture of pulp/sugar content of pulp and texture of pulp/ripening stages were negatively correlated, while pulp/peel ratio and moisture content of pulp were positively correlated. Chips packed in 80 μm high-density polyethylene pouches and stored at various relative humidities had extended shelf-life compared with the low-density polyethylene packed chips stored at the same relative humidities. This was due to the inadequacy of the low-density polyethylene in giving the required protection against moisture transmission thereby resulting in soggy chips in shorter periods. The implication of the findings on the formulation of a guideline for the processing of a good-quality plantain chips for the marketing system is discussed.     

不同贮存条件对海藻油氧化稳定性影响

以过氧化值为指标,考察空气、温度、光照等环境条件对海藻油稳定性影响,然后采用Schall烘箱加速氧化法,以POV和DHA含量为指标,通过L9(34)正交试验,从抗氧化剂TBHQ、VE、Vc棕榈酸酯优选海藻油复合抗氧化剂;及研究充N2保护、充N2保护结合添加抗氧化剂对海藻油稳定性影响。结果表明:空气,高温及光照均可显著加速海藻油氧化,降低海藻油稳定性;抗氧化剂TBHQ、VE、Vc棕榈酸酯能明显延缓海藻油氧化,影响顺序为Vc棕榈酸酯TBHQVE,最佳抗氧化剂组合为0.01%Vc棕榈酸酯+0.02%TBHQ+0.50%VE;充N2保护也能提高海藻油氧化稳定性,但效果比最佳复合抗氧化剂为差;充N2保护结合添加抗氧化剂能有效提高海藻油氧化稳定性。     

不同包装材料对乌龙头贮藏品质的影响

目的 研究不同包装材料对乌龙头贮藏品质的影响。方法 以‘长白’品种乌龙头为材料, 采用不同包装材料[普通聚乙烯(polyethylene, PE)食品袋(对照)、PE气调保鲜袋、聚氯乙烯(polyvinyl chloride, PVC)保鲜袋、PVC硅窗保鲜袋]对乌龙头进行贮藏, (1±1)℃下贮藏15 d, 研究包装材料对乌龙头感官品质、腐烂指数、呼吸强度、失重率、叶绿素含量、维生素C (vitamin C, VC)含量、粗纤维含量、丙二醛(malonaldehyde, MDA)含量、过氧化物酶(peroxidase, POD)活性和多酚氧化酶(polyphenol oxidase, PPO)活性等相关生理指标的影响。结果 3种保鲜袋均可以显著延长乌龙头贮藏期, 其中PVC硅窗保鲜袋的保鲜效果最佳, 与对照(PE食品袋)相比, 呼吸高峰出现推迟3 d。贮藏至12 d时, PVC硅窗保鲜袋的叶绿素含量和维生素C含量分别是对照的2.1倍和1.9倍, 与对照相比, 感官评分提高29.1%, 腐烂指数、失重率、粗纤维含量和MDA含量分别下降86.4%、50.3%、45.8%和42.4%, POD和PPO含量分别下降了37.5%和52.7%。结论 PVC硅窗保鲜袋可显著抑制乌龙头贮藏期间感官品质和叶绿素含量的下降, 抑制其腐烂, 贮藏期延长3 d。     

Influence of frozen storage and packaging on oxidative stability and texture of bread produced by different processes

The influence of packaging barrier properties and frozen storage on phenolic and phytosterol content, oxidative stability and crumb texture of frozen dough, part-baked and fully baked frozen bread was investigated in comparison to conventionally produced bread. Samples were stored either in blue coloured high density polyethylene (PE-HD) or transparent polyester-polyethylene-ethylene-vinyl alcohol copolymer (PET-PE/EVAL/PE) pouches for 22 days at −18 °C. Packaging materials were different in oxygen permeability: 3.67 cm³m⁻²day⁻¹ bar⁻¹ for PET-PE/EVAL/PE and 2080 cm³m⁻²day⁻¹ bar⁻¹ for PE-HD material, which did not significantly change during storage. Total phenolic content and oxidative stability of bread samples decreased during storage depending on the process. Frozen dough bread had the lowest phenolics decrease and the highest oxidative stability. Total phenolic content and oxidative stability of frozen breads during 8 days were similar to conventional bread. The phenolics reduction was higher for samples stored in PET-PE/EVAL/PE laminate than in PE-HD packaging. Total sterol content did not significantly change during bread storage in investigated packaging and did not contribute to the oxidation. Bread firmness was affected only by the process and not by the storage time and packaging material.     

食用油使用过程中存贮条件对其氧化稳定性的影响研究

研究了大豆油、菜籽油、棕榈油等几种食用油在使用过程中不同存贮条件下的氧化稳定性。将食用油启封,放置在不同的环境里,检测其过氧化值和酸值的变化。结果表明:避光存贮31 d,食用油的过氧化值均低于8 mmol/kg,酸值(KOH)达到0.26~0.35 mg/g;而在室内日光直接照射的条件下存贮31 d,各食用油的过氧化值均高于10 mmol/kg,酸值(KOH)达到0.35~0.45 mg/g。实验表明,启封后的食用油,存贮于避光处可以连续使用30 d以上,而置于室内日光直接照射条件下,其连续使用期只有3周。对比实验中,棕榈油氧化稳定性优于其他油脂。     

Effect of muscle,ageing time and modified atmosphere packaging conditions on the colour,oxidative and microbiological stability of packed beef

The objective of this study was to evaluate the influence of two different vacuum ageing times (7 and 14 days) and the impact of the modified atmosphere packaging (MAP) configuration (gas/product ratios: 0.5 and 1 and gas composition: 70% O₂ + 30% CO₂ and 40% O₂ + 30% CO₂ + 30% N₂) on the quality of fresh beef during subsequent storage at 4 °C. For this purpose, three separate experiments were performed. For each experiment, two different muscles (Longissimus dorsi and Biceps femoris) were sampled from four double‐muscled Belgian Blue beef carcasses. Next to colour, also the evolution in microbial load, pH, O₂ and CO₂ in the headspace and lipid oxidation at the meat surface were evaluated. A vacuum ageing for 14 days compared with 7 days resulted in a higher initial microbial load on the day of MAP packaging, which resulted finally in a significantly shorter shelf life. This ageing effect was less pronounced on the colour stability and lipid oxidation of the meat samples. No significant influence of the packaging configuration on any of the analysed parameters (colour, microbial load, pH and lipid oxidation at the meat surface) was observed.     

迷迭香活性包装对虾仁冷藏过程中脂质氧化与 质构的影响

目的研究不同浓度迷迭香活性包装对虾仁冷藏过程中脂质氧化与质构的影响。方法将不同浓度的迷迭香加入包装材料来保藏虾仁,研究冷藏过程中虾仁过氧化值(peroxide value,POV)、硫代巴比妥酸(thiobarbituric acid reactive substance,TBARS)值、巯基(sulfhydryl,SH)、Ca~(2+)-ATPase活性和质构特性的变化。结果迷迭香活性包装对冷藏期间虾仁的脂质氧化有一定的抑制作用,而且和迷迭香的浓度呈正相关。在虾仁冷藏的12天内,迷迭香添加量为0.75 mg/cm~2实验组的过氧化值相对于空白对照组降低47%,TBARS相对于空白对照组降低31%。质构数据表明,迷迭香活性包装能延缓虾仁硬度、弹性、咀嚼性的改变。结论迷迭香活性包装能有效抑制冷藏虾仁的品质变化,并能延缓质构劣变,是一种有潜力的虾仁包装技术。     

包装材料对贮藏期荔枝汁品质及非酶褐变的影响

研究了聚酯(PET)瓶、聚乳酸(PLA)瓶和聚酯/铝箔/聚乙烯(PET/Al/PE)复合袋装荔枝汁在25℃避光贮藏时的品质变化和非酶褐变情况,采用偏最小二乘法回归(PLSR)分析包装材料对荔枝汁非酶褐变的影响。结果表明:贮藏过程,PLA瓶装荔枝汁的L-抗坏血酸(L-AA)发生快速降解,PET瓶和复合袋中的L-AA降解缓慢;贮藏初期,溶解氧浓度(DOC)均急剧下降,贮藏后期,除PLA瓶中的DOC快速上升外,其它包装材料中的DOC均平缓下降并趋于稳定。包装材料阻隔性能对L-AA含量和DOC有显著(p<0.05)影响。蔗糖不断水解,果糖和葡萄糖含量在贮藏初期快速地增加,然后缓慢下降。氨基酸总量和总酚含量不断下降。可溶性固形物(TSS)含量缓慢上升,pH缓慢下降。5-HMF含量和褐变指数不断上升。包装材料阻隔性能使得荔枝汁中的溶解氧浓度差异,溶解氧能引起L-AA的降解和酚类物质氧化聚合,导致荔枝汁发生非酶褐变。     

贮藏条件对冷榨精炼核桃油脂氧化酸败的影响

以冷榨核桃油为对象,研究其精炼前后的各项理化指标,并考察气体成分、温度、光照、金属离子以及抗氧化剂对冷榨精炼核桃油在贮藏过程中酸价和过氧化值的影响。结果表明:冷榨核桃油精炼后各项指标远低于精炼前,均符合国家食用油脂标准。贮藏过程中气体成分、温度、光照和抗氧化剂对冷榨精炼核桃油的酸价和过氧化值影响显著(P 0. 05),添加不同金属离子对油脂氧化酸败影响不显著(P 0. 05)。在贮藏温度5℃并添加0. 02%特丁基对苯二酚(tert-butyl hydroquinone,TBHQ)的条件下可有效延缓精炼核桃油脂品质劣变,贮藏28个月时酸价低于国家标准74%,过氧化值低于国家标准2%。     

包装材料、储存环境及储油罐充氮对亚麻籽油保质期的影响

亚麻籽油富含多不饱和脂肪酸,易氧化,保质期较短。以过氧化值为评价指标,研究包装材料、储存环境及储油罐充氮对亚麻籽油保质期的影响。结果表明：避光包装材料、暗光条件储存,亚麻籽油的保质期可适当延长;不论什么包装材料的亚麻籽油,最佳食用时间限制在3个月内;包装瓶的气密性和灌装压盖的质量一定程度上影响亚麻籽油的保质期;储油罐间歇充氮方式较连续充氮方式节能,两者效用相同,均可延长亚麻籽油的保质期。     

Effects of type of packaging materials on physicochemical,microbiological and sensory characteristics of durian fruit leather during storage

A study on storage stability of durian leather was carried out at room temperature using four types of packaging materials—laminated aluminium foil (LAF), high-density polyethylene (HDPE), low-density polyethylene (LDPE) and polypropylene (PP) films—for 12 weeks. Analyses on physicochemical, microbiological and sensory characteristics were conducted at weeks 0, 2, 4, 8 and 12. Analyses for sugar, fat and caloric contents were conducted at the beginning and the end of storage period. Moisture contents and water activity (A_w) fluctuated during storage but tended to decrease after week 8. Non-enzymatic browning increased significantly (P<0·05) for all samples in packaging materials used; the highest increases were observed in LDPE-packed leather. The increases were related to the changes in colour of samples during storage. The longer storage time, the higher L and b values and the lower a value. The pH, although it fluctuated in the first weeks, slightly increased at the end of the storage period, while the hardness for each sample gradually increased during the storage. Microbial analyses showed that total mesophilic bacteria (TMB) and total moulds and yeast (TMY) counts were low, where after 12-week storage TMB and TMY were less than 60 and 140 cfu g⁻¹, respectively. Organoleptically, for all attributes evaluated, all samples were acceptable by panelists during the 12-week storage period. © 1998 SCI.     

Effects of calf diet, antioxidants, packaging type and storage time on beef steak storage

The effect of basal dietary supplemented with vegetable oils plus vitamin E (sunflower, soybean, linseed and a basal diet control), type of packaging (MAP or vacuum), addition of natural antioxidant (grape seed, rosemary) and storage time (0, 7, 14 and 21 days) on lipid oxidation, color stability, vitamin E content, and total aerobic bacterial counts in steaks of Longissimus thoracis was studied. The triple interaction diet × time × packaging affected oxidative stability, redness and yellowness of the meat. TBARS values did not increase with time in vacuum-packaged samples for all dietary treatments. However, samples from MAP and control showed the highest TBARS values after 21 days of storage (0.72 mg MDA/kg of meat, P < 0.05). Both exogenous antioxidant extracts and MAP maintained low total aerobic counts in steaks until the 21st day. Calves should be fed a diet supplemented with L-VE, stored in MAP and treated with grape seed extract to extend the shelf life of their meat.     

Evaluation of oxidative stability of sweet and bitter almond oils under accelerated storage conditions

This study aimed to investigate the oxidative stability of cold-pressed bitter and sweet almond oil under accelerated aging conditions. The oxidative stability of both oils was analyzed using as physicochemical metrics: fatty acid (FA) composition, sterol content, chlorophyll and carotenoid level, tocopherol level, iodine index, free fatty acid, Peroxide value and specific extinction coefficients K232–K270. The variations of these parameters were evaluated over four weeks at 60 °C. The results showed that carotenoid, total sterol, and tocopherol levels were decreased, the free fatty acid, Peroxide value, K232 and K270 parameters increased slightly for both oils, while, FA profiles and Iodine value did not significantly vary over four weeks. After four weeks, sweet almond cold-pressed oil still presents an excellent physicochemical profile. Bitter almond oil presents after the same delay much less satisfactory properties.     

Effects of palm oil quality and packaging on the storage stability of dry vegetable bouillon paste

Vegetable bouillon paste, prepared by dry-mixing of pre-produced dry ingredients with addition of semisolid palm oil, was stored at the slightly elevated temperature of 40 °C for up to 12 weeks for comparing modified atmosphere packaging (MAP; oxygen concentration initially below 0.5%) packaging with free availability of oxygen in order to identify the mechanisms leading to quality degradation. An increased browning and increased formation of volatile compounds related to Maillard reactions and oxidation of secondary lipid oxidation products were observed for the vegetable bouillon paste stored without limiting the oxygen availability. The use of palm oil (kept liquid by heating to 50 °C for one week) was further found to promote quality degradation as compared to fresh palm oil when the availability of oxygen was not limited by the packaging of the vegetable bouillon paste. For modified atmosphere packaging, the effect of the quality of the oil on storage stability of the product was less pronounced.     

Effects of sheep production systems on oxidative storage stability of lean lamb patties

Rambouillet lambs were assigned to three production systems varying in physical environment and diet: RF (a new, raised-floor feeding structure, with animals fed a pelleted mixture of 85% oat hay, 7.5% barley and 7.5% molasses); FL (a feedlot, with animals fed high-concentrate rations); and P (a pasture, with animals given access to the pasture and a high-concentrate supplement). Lengths of time on feed were adjusted to produce similar final shorn weights for each system. Ground meat patties were made with knife-separable lean from hind legs and aerobically refrigerated. Fat content of patties was not significantly different between RF and FL or P, while total unsaturated fatty acid percentage was slightly lower (P<0.05) for RF treatment. Patty color (redness) was most stable for RF. Lipid oxidation in raw patties also was lower (P<0.05) for RF than FL, but oxidation in cooked patties was greater for RF.