Packaging of Olive Oil: Quality Issues and Shelf Life Predictions

Olive oil has gained much appreciation among consumers worldwide leading to increased markets as well as greater consumer expectation and thus more challenges for the relevant food sector. By understanding the product, its interactions with the environment, and the protective role of the package, decisions can be made on the barrier properties required of the packaging materials to achieve the desired shelf life. To this end, the shelf life of packaged olive oil under various storage and distribution environments can be predicted by mathematical modeling. This review examines the basic factors affecting the shelf life of olive oil in different packaging systems and describes the main oxidative degradation mechanisms for them. Since an experimental investigation to correlate the basic quality factors and the shelf life of a product is time- and effort-consuming, the use of mathematical modeling for the prediction of packaged olive oil shelf life is also discussed. In the presented works, shelf life predictions were based on the most consumer-related attributes; namely, the evolution of olive oil flavor compounds under various packaging and storage conditions. The validation of the simulations against known experimental results showed a very good correlation, confirming the value of the mathematical approach for a quick and accurate prediction of shelf life of oxidation-sensitive products.     

Packaging of Olive Oil: Quality Issues and Shelf Life Predictions

Olive oil has gained much appreciation among consumers worldwide leading to increased markets as well as greater consumer expectation and thus more challenges for the relevant food sector. By understanding the product, its interactions with the environment, and the protective role of the package, decisions can be made on the barrier properties required of the packaging materials to achieve the desired shelf life. To this end, the shelf life of packaged olive oil under various storage and distribution environments can be predicted by mathematical modeling. This review examines the basic factors affecting the shelf life of olive oil in different packaging systems and describes the main oxidative degradation mechanisms for them. Since an experimental investigation to correlate the basic quality factors and the shelf life of a product is time- and effort-consuming, the use of mathematical modeling for the prediction of packaged olive oil shelf life is also discussed. In the presented works, shelf life predictions were based on the most consumer-related attributes; namely, the evolution of olive oil flavor compounds under various packaging and storage conditions. The validation of the simulations against known experimental results showed a very good correlation, confirming the value of the mathematical approach for a quick and accurate prediction of shelf life of oxidation-sensitive products.     

Elevated concentrations of oxygen on the stability of live mussel stored refrigerated

The stability of bivalve molluscs was studied in live mussels (Mytilus galloprovincialis) packaged under modified atmospheres. Studies of physical, chemical, microbiological and sensory parameters have detailed these changes in the live packaged mussels. The highest survival was achieved at high oxygen concentrations, i.e. 75%, in the absence of carbon dioxide. The improved storage conditions promote shelf life in 80% of the packaged mussels, reaching a storage life of 6 days when held at 2–3 °C, whereas control molluscs packaged in air did not exceed 3–4 days when stored under the same conditions. Sensory analysis of cooked products from live mussels packaged under 75% oxygen:25% nitrogen were optimum throughout the period of storage. Secondly, the results for the most effective treatment were compared with those for an approximate 75–80% oxygen mixture achieved by applying partial vacuum to the packaging machine. This option employed only oxygen and decreased packaging time, which reduced mussel packaging stress by avoiding elevated vacuum conditions. It provided operational and economic advantage to commercial mussel packaging.     

Shelf Life of Sunflower Kernels

One raw and two oil roasted samples of sunflower kernels packaged in paper bags and in two types of low oxygen atmosphere pouches were stored at 5, 21 and 38°C. Quality of the stored samples was monitored by an expert sensory panel, peroxide, hexanal, free fatty acids and moisture determinations. Liking ratings, obtained with 99 consumers after 24 wk storage, were used to select end points for expert sensory ratings. The shelf life for roasted sunflower kernels was greater than 12 month when stored in nitrogen flushed pouches and as low as 8 wks when exposed to air at 38°C. Hexanal was a better index for shelf life of roasted sunflower kernels than was peroxide. The shelf life of raw sunflower kernels was > 12 month in packages providing some moisture but no oxygen protection.     

Effect of different concentrations of carbon dioxide and oxygen on the growth of pathogenic Yersinia enterocolitica 4/O:3 in ground pork packaged under modified atmospheres

The influence on Yersinia enterocolitica counts of a gradual increase of carbon dioxide concentrations (percentage by volume in air) during packaging and storage of ground pork meat artificially contaminated with this pathogen was evaluated. Ground meat was packaged under customary conditions using modified atmospheres with various carbon dioxide percentages (0, 30, 50, 70, and 100% CO2 by volume; for atmospheres of less than 100% CO2, the rest of the gas was O2). The packs were stored at 2 degrees C for 12 days. During the entire storage time, counts of Y. enterocolitica were determined by the spread plate method for direct plate counts (DPCs). Microbiological shelf life of the stored ground pork also was assessed by total mesophilic aerobic bacterial plate counts (APCs). Y. enterocolitica counts were not significantly different (P > or = 0.05) in the ground pork packaged under the various CO2-enriched atmospheres. The growth of Y. enterocolitica was nearly entirely inhibited in all tested modified atmospheres containing the protective CO2. However, in ground pork packaged with 100% oxygen, there was a significant decrease (P < or = 0.05) in the DPC for Y. enterocolitica from 4.30 log CFU/g (day 0) to 3.09 log CFU/g at the end of the storage time (day 12). The decrease was presumably due to the marked increase in APC seen only in those packages stored under 100% O2. Packaging with high CO2 concentrations had significant inhibitory effect (P < or = 0.05) on the growth of mesophilic aerobic bacteria.     

Effects of lipid,PET/PE and PA/PE with high-pressure processing

The mutual effects between food components and packaging materials under high-pressure processing was investigated. Pouches made of Polyethylene terephthalate/Polyethylene and Polyamide/Polyethylene packaging olive oil and glycerol trioleate were subjected to different pressures and holding times, and then stored at 23 ± 2^oC for 40 days. The results proved that there were significant effect between lipid and packaging under high-pressure processing treatment. High pressure would be beneficial to extend food shelf life and affect the enthalpy of fusion of packaging materials, especially when making contact with olive oil which probably acted as a plasticizer to change the polymer structure.     

SHELF-LIFE SIMULATION OF PACKAGED RICE CRACKERS

ABSTRACT

Two varieties of rice crackers (RC‐1 and RC‐2) were packaged in two types of packaging materials, polyethylene and polypropylene pouches, and stored at 30C/75% RH and 30C/85% RH to simulate actual storage conditions and determine shelf‐life. The main composition differences in the samples were in their fat content (1.87% for RC‐1 and 21.09% for RC‐2) and initial moisture content (4.12% for RC‐1 and 2.28% for RC‐2). The shelf‐life of this product is mainly affected by moisture adsorption as evidenced by sensory evaluation. Guggenheim‐Anderson‐de Boer (GAB) model was used to fit the moisture sorption isotherm. Good precision of fit was found as measured by a determination coefficient (R²) close to 1. The shelf‐life was then predicted based on the relationship between permeability coefficient of the packaging materials and moisture adsorbed by the rice crackers determined by the GAB equation. The validation of the simulations against the experimental shelf‐life gave R² of 0.90 and 0.51, and root mean square error of 2.93 and 5.20 for RC‐1 and RC‐2, respectively. The simulation model was found to be applicable for a rapid and accurate shelf‐life prediction of RC‐1. However, a large difference between experimental and simulated shelf‐life of RC‐2 was probably because the moisture content may not be the only parameter influencing the shelf‐life of the RC‐2 samples. Other factors may also significantly affect the shelf‐life characteristics of the packaged rice crackers.

PRACTICAL APPLICATIONS

For a low‐moisture food product, actual storage testing by a long‐term stability study involves storing a packaged product under typical storage conditions and examining the product at regular time intervals. The testing is costly and time consuming, since most low‐moisture food products have a shelf‐life of several weeks or even months. This paper describes the shelf‐life prediction of two varieties of rice crackers having different compositions using a simulation model based on the relationship between barrier property of the packaging materials and moisture adsorbed by the rice crackers determined by the Guggenheim‐Anderson‐de Boer (GAB) model. The shelf‐life simulation provides a powerful support tool for shelf‐life estimation and packaging development.

     

亚麻籽油的保质期研究

通过考察不同光照条件、包装材料对亚麻籽油贮藏过程中过氧化值、酸价的影响,研究自然条件下亚麻籽油的保质期。结果表明:光照对亚麻籽油的贮藏性能有一定影响,避光有利于亚麻籽油的贮藏稳定性,散射和直射条件下对亚麻籽油贮藏稳定性的影响差别不大;对比PET瓶、透明玻璃瓶、棕色玻璃瓶、马口铁瓶不同包装材料贮藏亚麻籽油,玻璃瓶对亚麻籽油的贮藏性能优于马口铁瓶,马口铁瓶优于PET瓶,棕色玻璃瓶较透明玻璃瓶对亚麻籽油的贮藏稳定性有较大提升,棕色玻璃瓶储藏的亚麻籽油保质期可以达到18个月。     

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。     

基于包装内顶空氧气浓度变化的奶粉货架期预测

目的：通过包装顶空氧气浓度变化确定全脂奶粉耗氧量,进而预测包装奶粉货架期。方法：利用相对耗氧率表征全脂奶粉氧化特性,分析多个氧化指标确定奶粉耗氧量阈值;综合包装材料氧气渗透性与奶粉氧化特性表征顶空氧气浓度变化,建立奶粉耗氧总量模型预测奶粉货架期;结合45℃下聚对苯二甲酸乙二脂/聚乙烯袋装全脂奶粉加速氧化实验进行模型验证。结果：全脂奶粉耗氧量阈值为0.041 47 mg/g,加速氧化贮藏期间包装顶空氧气体积分数实验数据和模型预测数据规律一致,实验货架期和理论预测货架期的相对偏差为6.06%。结论：可通过包装顶空氧气体积分数变化来预测全脂奶粉包装货架期。     

Nisin、姜油协同高氧气调包装熟肉保鲜效果的研究

将熟猪肉采用Nisin和姜油处理,结合60%O2+20%CO2+20%N2和80%O2+20%CO2高氧气调包装,于低温和常温条件下贮藏,研究高氧气调包装对熟猪肉制品的保鲜效果,以空气包装的熟肉制品为对照。结果表明:高氧气调包装可显著抑制熟肉制品贮藏期间菌落总数的上升和感官品质的下降,贮藏后期能有效抑制TBA值的上升,防止肉制品的氧化;0.05%乳酸链球菌素、0.08%姜油结合80%O2+20%CO2高氧气调包装,可使肉制品达到最佳的保藏效果,低温下(0～4℃)至少可以保藏28d,常温下可以保藏15d。     

包装材料结合活性包装对荞麦半干面常温货架期及品质的影响

为了延长荞麦半干面的常温货架期,以聚偏二氯乙烯(PVDC)和聚乙烯(PE)为包装材料,采用不同活性包装方式(脱氧包装和脱氧结合酒精缓释包装)对其进行包装处理。考察脱氧剂、酒精缓释剂和不同包装材料对荞麦半干面货架期和储藏期间品质的影响。测定荞麦半干面在储藏期间菌落总数、酸度值、p H值、质构特性、感官品质和包装袋内顶空氧气含量、顶空酒精浓度的变化。结果表明:储藏期间菌落总数整体呈现上升趋势,脱氧结合酒精缓释包装协同抑制微生物生长。储藏9 d后,脱氧结合酒精缓释包装的面条菌落总数均未超过106cfu/g,同时显著抑制了理化品质的劣变(P0.05);脱氧剂的吸氧量越大,24 h内除氧速率越快,抑菌效果越显著;相同活性包装方式下,与PE包装材料相比,PVDC包装材料能增强其延长荞麦半干面常温货架期的作用效果。与其他包装方式相比,脱氧(200 m L)结合酒精缓释PVDC包装将荞麦半干面货架期延长至16 d,并且维持了面条储藏期间的品质。     

Determination of Critical Oxygen Level in Packages for Cooked Sliced Ham to Prevent Color Fading During Illuminated Retail Display

ABSTRACT:  The effect of packages with different oxygen transmission rates (OTR), different gas-to-product-volume (GP) ratios, and various levels of residual oxygen after packaging on the color stability of cooked ham exposed to commercial retail light conditions was studied. Sliced cooked ham was packaged in thermoformed packages with OTR of 0.04 and  0.06 mL O₂/pkg × 24 h  and GP ratios of 2.6 and 4.1. After packaging, the packages were additionally divided into groups with 4 levels of residual oxygen ranging from 0.09% to 0.46%. The packaged ham was stored in darkness at 4 °C up to 33 d, and during the storage period samples were withdrawn and exposed to light for 2 d before instrumental and visual color evaluation. In order to maintain an acceptable color of this particular ham product when exposed to typical retail light conditions, the highest acceptable level of oxygen in the headspace of the packages was 0.15% oxygen at the time of illumination. This threshold level was independent of the storage time before light exposure. A residual oxygen level of below 0.15% just after packaging combined with the package with the lowest OTR  (0.04 mL O₂/pkg × 24 h)  and the lowest GP ratio (2.6) was the optimal condition for maintaining the color of the tested ham product throughout the entire storage period.     

Effect of oxygen absorber, nitrogen flushing, packaging material oxygen transmission rate and storage conditions on quality retention of raw whole unpeeled almond kernels (Prunus dulcis)

The present study investigated the effect of active packaging, nitrogen flushing, container oxygen barrier and storage conditions on quality retention of raw whole unpeeled almonds. Almond kernels were packaged in: a) polyethylene terephthalate//low-density polyethylene (PET//LDPE), and b) low-density polyethylene/ethylene vinyl alcohol/low-density polyethylene (LDPE/EVOH/LDPE) pouches under N_2, with or without an oxygen absorber, heat-sealed and stored for a period of 12 months. Quality parameters monitored were: peroxide value (PV), hexanal content, color, fatty acid composition and volatile compounds. PV ranged between 0.17 for fresh almonds and 9.22 meq O₂/kg oil for almonds packaged in PET//LDPE pouches under N₂ exposed to light at 20 °C after 12 months of storage. Respective values for hexanal were <28.5 μg/kg and 4.88 mg/kg. Polyunsaturated fatty acids (PUFA) and saturated fatty acids (SFA) increased with a parallel decrease of monounsaturated fatty acids (MFA) after 12 months of storage in all treatments. Likewise, volatile compounds such as aldehydes, ketones, alcohols, alkanes and aromatic hydrocarbons increased indicating enhanced lipid oxidation. Color was the parameter least affected. Use of the oxygen absorber provided a shelf life of at least 12 months for all samples irrespective of container oxygen barrier, lighting conditions and storage temperature.     

Estimating packaging atmosphere–temperature effects on the shelf life of cod fillets

The behaviour of the natural microflora (total bacterial count, psychrotrophic bacteria, total coliforms, and lactic acid bacteria) of fresh cod fillets packaged in air, under vacuum, in a modified atmosphere with low oxygen concentration (5%) and in a modified atmosphere with high oxygen concentration (80%) was monitored during storage at different isothermal conditions from 4 to 12 °C. The growth data of the total bacterial count and total coliforms were used to model kinetically the shelf life of the samples in order to check the effects of storage temperature and packaging atmosphere. The acceptability times were compared with the stability times to establish if the shelf lives predicted were correlated. At 4 °C, cod fillets packaged under vacuum and in a modified atmosphere with low oxygen concentration had a higher shelf life (6.00 and 5.42 days), calculated from the growth of the total bacterial count, than the samples packaged in other atmospheres (1.96 and 2.62). Kinetic modelling could be valuable for the prediction of microbial fish quality loss.     

气调包装对百香果贮藏品质的影响

为探讨不同气调包装材料对百香果贮藏品质的影响,以‘紫香1号’百香果为试材,对其进行活性袋包装和普通聚乙烯袋包装两种处理,包装好后封口,并于温度（25±1）℃、相对湿度70%～80%的条件下贮藏;相同成熟度未进行包装的果实于相同条件下贮藏作为对照,监测贮藏期间百香果的质量损失率、可溶性固形物与可滴定酸含量、果皮的L*、a*、b*值、果皮缺陷指数及贮藏寿命。结果表明,与对照相比,两种气调包装均减缓了果实质量损失率的上升,延缓了果皮缺陷指数及其他与百香果后熟有关的物理化学变化,能延长贮藏寿命至少6 d;采用活性包装的百香果品质保持得更好,货架期更长。     

Shelf life predictions for packaged olive oil using flavor compounds as markers

The experimentally-derived amounts of five selected flavor compounds, namely hexenal, 2-pentyl furan, (E)-2-heptenal, nonanal, and (E)-2-decenal, all produced during the oxidation of extra virgin olive oil packaged in various storage conditions (glass/PET/PVC bottles; 15/30/40 °C temperature; light or dark conditions) for one year, were used in a mathematical model for calculating the probability that the olive oil would not have reached the end of its shelf life (P_safe) after a certain storage period time. The storage times corresponding to probabilities of 70%, 50% and 30% were also calculated. On the basis of these results, an optimal group of flavor compounds were selected that were highly correlated to the degradation factors (storage conditions), and therefore the P_safe, of the oil. These flavor compounds could then be used as markers to identify the cause of the oxidative degradation (the storage history) of the olive oil.     

Effect of combined application of plant extract and vacuum packaged treatment on the quality of hot smoked rainbow trout

The effect of plant extract (bay leaf, rosemary, black cumin seed and lemon oil) treatment on the shelf life of vacuum-packaged fish was studied. Hot smoked rainbow trout was treated with 1 % plant extracts, and their shelf lives were compared with those of control (only vacuum packaged) samples. Samples were stored at 2 °C and sensory evaluation as well as chemical and microbiological analyses were conducted weekly. The control group was spoiled after four weeks of storage. In contrast the addition of plant extracts decreased microbiological activity. The results obtained from this study showed that the shelf life of hot smoked trout stored in cold storage (+2 °C), as determined by overall acceptability of all data, was 6 weeks for rosemary, black cumin seed, and lemon oil treatment plus vacuum packaged fish and 7 weeks for bay leaf oil treatment plus vacuum packaged smoked fish.     

气调包装对牛肉保鲜效果的影响

冷却牛肉的嫩化及保鲜问题在一定程度上制约了冷却牛肉的普及和发展,气调包装是一种通过调节和控制食品所处环境中气体组成的保鲜方法,并在一定时间内保持相对稳定,以抑制或延缓产品的变质过程,从而达到延长保鲜期和提高保鲜效果的目的。本实验以牛肉为包装对象,通过研究5种不同透气性包装材料在气调包装(45%氧气+30%二氧化碳+25%氮气)气体比例的充气包装方式下,每天对牛肉菌落总数、酸碱值、挥发性盐基氮值、色泽、包装袋内气体含量的变化和剪切力进行测定分析。结果表明:以聚丙烯-聚乙烯-聚对苯二甲酸乙二醇酯的气调包装材料效果最佳。     

奇亚籽油储藏稳定性研究及货架期预测

为研究奇亚籽油储藏稳定性,以液压法制备的奇亚籽油为原料,探讨储藏温度、氧气和光照条件对奇亚籽油过氧化值、酸价、K₂₃₂、K₂₆₈和TBA的影响,并应用一级动力学模型结合Arrhenius方程建立过氧化值、酸价两个氧化指标随储藏温度、储藏时间变化的货架期预测模型,预测奇亚籽油货架期。结果表明：奇亚籽油的氧化稳定性受光照、氧气和温度的影响,在避光、密封、低温的储藏条件下能有效降低过氧化值、酸价等的增长速率,延长储藏时间;通过模型推算得出密封、避光条件下奇亚籽油在25℃条件下的货架期为94 d。