Is It Advisable to Store Olive Oil in PET Bottles?

To assess the role of the container material on the quality of olive oil, literature results concerning the analytical definition of the quality of oils stored in PET or glass bottles were critically reviewed. The performance of active and passive barrier PET containers may move towards that of glass bottles. The influence of storage conditions was also considered: the main factors affecting the sensory quality loss upon storage are light and the initial oil oxygen concentration, aside from the bottle material. Further research needs are anticipated since new active and passive barrier bottles indeed deserve further attention.     

Effect of menadione (vitamin K3) addition on lipid oxidation and tocopherol content in plant oils

The effect of added menadione (vitamin K₃) to stored corn and wheat germ oil on the dissolution and dimerization of natural tocopherols and auto‐oxidation of triacylglycerols were investigated. Samples of corn and wheat germ oils pure and with added menadione were stored at +20°C in brown and transparent glass bottles. During storage their peroxide value, changes of the content of fatty acids and dissolution of tocopherols were measured. Destruction of individual tocopherols in tested oils with added menadione stored in both dark and transparent glass bottles was greater than in these oil samples without menadione. However, the degradation of individual tocopherols was different in each oil. Addition of menadione to the both oils resulted in accelerated the process of auto‐oxidation of these oils. The corn oil stored in transparent bottles was oxidized faster than the one stored in brown bottles. The pro‐oxidant activity of menadione was additionally activated by light. In contrast, in the cause of germ oil, the process of auto‐oxidation was very fast regardless of sort of container. Addition of menadione to the plant oils influenced the dissolution of natural tocopherols but did not influence the dimerization of tocopherols. As from the experiment, the addition of menadione to the oils decreased their nutritive value.     

Diacylglycerol isomers in extra virgin olive oil: Effect of different storage conditions

An experimental investigation was carried out with the aim to investigate on the isomerisation of 1,2-diacylglycerols to 1,3-diacylglycerols as a function of the storage conditions, as well as to identify indices useful to evaluate the freshness of the oils. Two oils derived from two different cultivars (Coratina and Ogliarola barese) were stored for two years as follows: in bottles at dark; in clear glass bottles at light; in green glass bottles at light; in bottles at dark, the latter subjected to repeated opening and samplings to simulate domestic use. The obtained results evinced that during the storage period a significant increase in the 1,3-isomers was observed due to an isomerisation from the 1,2 to the 1,3 isomeric form, consequently the 1,3/1,2 ratio increased in both oils. The covariance analysis of the data showed that the isomerisation of diacylglycerols, taking place during time, was affected by the type of oil, probably due to the different initial hydrolysis level, but was not affected by the storage conditions. Among the parameters considered, the total diacylglycerols/1,3-diacylglycerols ratio could be used as freshness index of extra virgin olive oil, since it is not affected by either oil or storage conditions.     

Changes during storage of quality parameters and in vitro antioxidant activity of extra virgin monovarietal oils obtained with two extraction technologies

Extraction technology has a great effect on quality of olive oils. This paper studied 18 months of storage of two Sardinian extra virgin monovarietal oils obtained with a traditional and with a low oxidative stress technology. Oil samples were subjected to the following chemical analyses: acidity, peroxide value, ultraviolet light absorption K₂₃₂ and K₂₇₀, carotenoids, chlorophylls, tocopherols and total polyphenols. The antioxidant capacity of oils, polyphenol extract and oil extract (remaining after polyphenol extraction) was also determined as radical scavenging activity. The results show that both extraction technologies resulted in minor changes in legal and quality indices during storage, due surely to the high quality of the oils as well as to the very good storage conditions used. Oils obtained with the low oxidative stress technology showed lower peroxide value and acidity and resulted in up to 103% higher total polyphenol content as well as increased radical-scavenging activity, with respect to oils obtained with the traditional technology.     

Sensory characterisation and oxidative stability of walnut oil

This study was carried out in order to probe the extent of oxidative and flavour stability of walnut oil (WO) under conditions normally used for selling in retail markets, during a period of four months. Fresh WO was characterised by higher intensity ratings of nutty and oily film, and lesser ratings for pungent and astringent attributes. Low and similar values for sweetness and bitterness were also detected. The ratings for negative attributes (oxidised and painty) were close to zero. During the long‐term storage period, the extent of the oil oxidative degradation was more pronounced than flavour attributes deterioration. Peroxide values (PV), conjugated dienes and trienes increased significantly throughout the storage period, whereas tocopherol content and oxidative stability index showed significant reductions. Minor changes were observed in the overall flavour stability. Using a PV of 10 mequiv. O₂ kg^?1 oil as a quality criterion, WO stored in transparent glass bottles, exposed to fluorescent light (1100 Lux) and room temperature conditions, without addition of any antioxidant, could maintain an acceptable quality until two months of storage.     

Interaction of packaging materials and vegetable oils: oil stability

The effects of different plastic films (polyethyleneterephthalate, polyvinylchloride, polypropylene and polystyrene) on the stability of olive, sunflower and palm oils were studied at 24 and 37°C during 60 days of storage. The changes in peroxide value (PV) and thiobarbituric acid value (TBA) were significantly higher (p≤0.05) in the plastic bottles than in glass. Our study indicates that the plastic permeability has played a major role in oil stability. However, both butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) were found to leach out from plastics films into vegetable oils during storage. The rate of oxidation was not reduced by antioxidant migration from plastic films to oils. Natural antioxidant (vitamin E) retarded the oxidation rate, and this was dependent on its concentration in oils examined. The results showed that the ranking of stability of oil samples is PVC≥PET>PP≥PS. Further, the stability was dependent on the type of oil. Palm oil exibited high stability properties while the highest oxidation rate was observed in sunflower oil. In addition, increasing storage temperature accelerated the oxidation and limited the stability of vegetable oils.     

Antioxidant effect of essential oils of rosemary,clove and cinnamon on hazelnut and poppy oils

Antioxidant effects of essential oils from rosemary (Rosmarinus officinalis), clove (Syzygium aromaticum) and cinnamon (Cinnamomum zeylanicum) were determined on hazelnut and poppy oils. These essential oils were added to the oils at concentrations of 0.25% and 0.5%. Butylated hydroxyanisole (BHA) at 0.02% level served as standard besides the control groups for comparison. The samples were stored 50 °C in darkness for 14 days. The antioxidant activity of the essential oils was determined by measuring peroxide values (meq O₂/kg oil) at regular intervals. On the basis of peroxide value assay, the essential oils showed stronger antioxidant effect when compared to control groups. BHA was more effective than the essential oils, whilst it exhibited no antioxidative effect on the first few days of storage. Amongst the investigated essential oils, the cinnamon oil was the most effective on retarding lipid oxidation of crude oils, which was followed by clove and rosemary oils.     

Fluorescence spectroscopy in monitoring of extra virgin olive oil during storage

The present study demonstrates the use of fluorescence spectroscopy for monitoring changes in virgin olive oil during storage. Total luminescence and synchronous scanning fluorescence spectroscopy techniques were tested with the purpose to check their ability to monitor changes occurring in olive oil during storage in different conditions: in clear and green glass bottles exposed to light, and in darkness. Total luminescence spectra of the initial oil samples in n‐hexane solutions exhibited intense peaks, one with a maximum appearing at 320 nm in emission and 290 nm in excitation, attributed to tocopherols, and another appearing at 670 nm in emission and 405 nm in excitation, belonging to the pigments of the chlorophyll group. The intensity of these emissions decreased during storage depending on the storage conditions. Additional bands appeared in oils exposed to light in the intermediate range of excitation and emission wavelengths, arising from unidentified compounds. Bands attributed to tocopherols, chlorophylls and those tentatively ascribed to phenolic compounds were observed in the synchronous scanning fluorescence spectra, allowing monitoring of the storage effects on these constituents and their quantitative assessment after appropriate calibration. The results presented confirm the capability of the fluorescence techniques to monitor the quality of oil products.     

油样短期存放条件对过氧化值测定的影响

对两种食用植物油取样后,分装于塑料瓶和玻璃瓶且装样量不同,置实验室条件的不同光照和温度短期存放40d,其间每隔10 d测定过氧化值.研究结果表明,各种存放条件下短期存放的油样过氧化值都在增长变化,装具及装样量、光照和温度条件对短期存放的油样过氧化值测定都具较大影响.     

Influence of added menadione (vitamin K3) on dissolution and dimerization of tocopherols and autoxidation of triacylglycerols during storage of plant oils

The effect of added menadione (vit. K3) to stored rapeseed and soybean oil on the dissolution and dimerization of natural tocopherols and autoxidation of triacylglycerols was studied. Commercial rapeseed and soybean oils with added menadione and pure oil were stored at +20 degrees C in brown and transparent glass bottles. During storage their peroxide value, changes of the content of fatty acids and dissolution of tocopherols were measured. Destruction of individual tocopherols in tested oils with added menadione stored in both dark and transparent glass bottles were greater than in the oil samples without menadione. However, the degradation of individual tocopherols was different in each oil. Addition of menadione to the rapeseed and soybean oils resulted in the accelerated process of autoxidation of these oils. The oxidative state of the oils was lower in the oils stored in transparent bottles than in the oils stored in brown bottles. The prooxidant activity of menadione was additionally activated by light. Menadione added to the vegetable oils influenced the dissolution of natural tocopherols as well as their dimerization. It is conduced that addition of menadione to vegetable oils decreases their nutritive value.     

Influence of technology,storage and exposure on components of extra virgin olive oil (Bosana cv) from whole and de-stoned fruits

We investigated the influence of technology, storage and exposure on quality parameters, minor components, oxidative stability and antioxidant activity in two extra virgin olive oils of Bosana cv, obtained from whole (WO) and de-stoned fruits (DO), processed with a two-phase decanter. DO oils showed great stability and, consequently, had a longer shelf-life than WO oils. During storage, the former maintained lower values of free acidity, higher values of chlorophylls, carotenoids and α-tocopherol, longer oxidative stability and higher antioxidant activity than the latter. Peroxide indices were not significantly different between the two oils, while spectrophotometric indices, during storage, increased more in DO oils than in WO oils. The total phenol content behaviour patterns during storage were very similar in both oil samples, with a higher value in WO oils. Exposure to light significantly decreased the chlorophylls, carotenoid, phenol, α-tocopherol and stability values, as expected, but antioxidant activity was not influenced by exposure conditions.     

不同条件对油茶籽油储藏稳定性的影响

研究了不同加工工艺(压榨毛油、压榨精炼油、浸出精炼油)、不同容器(铁罐、无色玻璃瓶和塑料瓶)及不同光照条件(光照、避光)下油茶籽油的储藏稳定性.结果显示:不同加工工艺油茶籽油样品中浸出精炼油和压榨精炼油储藏稳定性较好,压榨毛油最差;光照是影响油茶籽油储藏稳定性的关键因素,油茶籽油包装及储藏要尽量采用不透光材料或避光储藏;3种容器材料中,铁罐储藏效果最好,玻璃瓶次之,塑料瓶最差.     

Effect of menadione (vitamin K3) addition on lipid oxidation and tocopherols content in plant oils

The effect of added menadione (vitamin K3) on stored corn and wheat germ oil on the dissolution and dimerization of natural tocopherols and autoxidation of triacylglycerols was investigated. Samples of corn and wheat germ oils pure and with added menadione were stored at +20 degrees C in brown and transparent glass bottles. During storage their peroxide value, changes of the content of fatty acids and dissolution of tocopherols were measured. Destruction of individual tocopherols in tested oils with menadione stored in both dark and transparent glass bottles was greater than in the oil samples without menadione. However, the degradation of individual tocopherols was different in each oil. Addition of menadione to the both oils resulted in accelerated the process of autoxidation of these oils. The corn oil stored in transparent bottles was oxidized faster than the one stored in brown bottles. The pro-oxidant activity of menadione was additionally activated by light. In contrast, in the case of germ oil, the process of autoxidation was very fast regardless of sort of container. Addition of menadione to the plant oils influenced the dissolution of natural tocopherols but did not influence the dimerization of tocopherols. As from the experiment, the addition of menadione to the oils decreased their nutritive value.     

Influence of the exposure to light on extra virgin olive oil quality during storage

An experimental investigation was carried out to study the influence that exposure to light has on the quality of extra virgin oil during a 12-month storage period by comparing it with the quality of extra virgin oil stored in the dark. The results showed that the oils stored in the light had significantly lower tocopherol, carotenoid and chlorophyll contents than did the same oils kept in the dark. Moreover, the oils stored in the dark mainly contained primary oxidation products, while the oils kept in the light contained secondary oxidation products as confirmed by the K₂₇₀ values which exceeded the legal limits even after purification by means of alumina. Overall, the results obtained showed that the shelf life of the oils exposed to light is shorter than that of oils kept in the dark, and that after only 2 months of exposure to light the oils examined could no longer be considered as extra virgin.     

不同贮藏条件下菜籽油品质变化的研究

本文采用不同贮藏容器(玻璃油壶、塑料油壶PET)、不同贮藏方式(油壶密封、油壶开盖)来研究菜籽油(无抗氧化剂、添加TBHQ)在食用过程中酸价和过氧化值的变化规律。结果表明：菜籽油在不同的贮藏容器中和不同的贮藏方式下的酸价和过氧化值均随着贮藏时间的延长呈现上升的趋势,而过氧化值的上升速度远大于酸价。密封条件下,玻璃油壶中菜籽油的酸价和过氧化值在6周之内均合格,塑料油壶则是5周;开盖条件下,所测指标均比密封时提前1周超过国家标准;添加TBHQ可以使菜籽油的酸价和过氧化值晚2周超过国家标准。当家庭购买充氮包装的食用菜籽油进行分装时,分装贮藏容器应选择玻璃油壶,用完之后立即密封,并且在6周之内食用完毕。     

Influence of olive storage period on volatile compounds and oil quality of two Tunisian cultivars of Olea europea,Chemlali and Chetoui

Olives (Olea europaea cv. Chemlali and Chetoui) used for oil production were stored, in plastic containers, at 5 °C for four different periods (0–3 weeks) before oil extraction. After storage, the oils were extracted from the fruits, and the acidity, peroxide value, coefficients of specific extinction at 232 and 270 nm, stability, pigments, total phenols, fatty acids, and volatile compounds were determined. The results showed that storage of fruits produced losses in the olive oil quality. During storage, a marked decrease in total phenols content was observed. The cultivar richer in phenols (862.16 mg kg^?1 in Chétoui) had a lower loss (25%). On the contrary, in Chemlali olive oil, the starting value of 728.52 mg kg^?1 decreased to 469.25 mg kg^?1, with a loss of 35%. Chétoui and Chemlali olive oils presented the highest oxidative stability before storage (58.76 and 47.05 h, respectively), while the lowest values were recorded using olives stored for 3 weeks (54.46 and 43.43 h, respectively). The changes in the volatile bouquet were determined using headspace solid phase microextraction (HS‐SPME). Thirty compounds were characterised by GC–FID and GC–MS. Compounds belonging mainly to alcohols, esters, aldehydes, ketones and hydrocarbons chemical classes characterised the volatile profiles.     

月桂叶精油抗氧化活性及在食用调味油中的应用

以月桂叶为原料,从总抗氧化活性、过氧化值、清除DPPH、清除羟基自由基4个指标对比了月桂叶精油和常用油脂抗氧化剂的抗氧化能力;并将月桂叶精油与基础油调配,采用电子鼻评价了油脂储藏的稳定性以及不同光照和油炸过程的品质变化。实验结果表明：当浓度为2.5×10-2 mg/mL、3.0×10-2 mg/mL时,精油的总抗氧化性能要优于其他单体抗氧化剂;在55℃的加速氧化过程中,当精油浓度达到0.3%时,调味油的抗氧化性能明显提升;以多力葵花籽油为基础油,0.8%的精油添加量进行调配,经过不同时间加速氧化的调味油表现出不同的气味信息,且不同储藏时间的油样可以很好区分。避光保存与自然光保存对油脂自身氧化速度影响不大,而全日光会加速氧化,在80天全日光保存后,油脂的过氧化值接近15 mmol/kg。电子鼻SQC分析显示,前三次煎炸后油的品质变化不大,从第四次煎炸开始,调味油的质量变化显著,并有新的挥发性物质产生。     

Oxidative stability of red wine stored in packages with different oxygen permeability

A young red wine was aged in containers with different oxygen permeability, i.e. glass, polyethyleneterephtalate (PET) and polyethyleneterephtalate including an oxygen scavenger (PETA), to determine variations in antioxidant components and antioxidant activity, determined as radical scavenging activity. The phenolic composition and the antioxidant activity of the wine were evaluated during approximately 24 weeks of storage at 20 or 30 °C. Significant changes were observed in total anthocyanin concentration in all samples, while other indexes such as total phenolics and total flavonoids remained stable during storage in all conditions. The antioxidant activity diminished in all samples, with differences between the various containers, both at 20 and 30 °C. HPLC analysis showed that important changes occurred in some flavonoid components (catechin, epicatechin, procyanidin TB2) and in most anthocyanidins in all storage conditions, with greater degradation at 30 °C and in PET bottles. Samples stored in PETA bottles showed the highest stability. The research demonstrated that ageing-related changes during storage are influenced by the oxygen permeability of the containers and can be slowed by the use of PET materials with enhanced oxygen barrier capacity.     

The effects of thyme (Thymus vulgaris) and rosemary (Rosmarinus officinalis) essential oils on Brochothrix thermosphacta and on the shelf life of beef packaged in high-oxygen modified atmosphere

The objective of the study was to determine the Minimal Inhibitory Concentration (MIC) of thyme (29.4% thymol, 21.6% p-cymene) and rosemary essential oils (27.6% 1,8-cineole, 13.5% limonene, 13.0% β-pinene) against Brochothrix thermosphacta and to establish the feasibility of their use as components of modified atmosphere during beef refrigerated storage. The minimum inhibitory concentration (MIC) of thyme oil against B. thermosphacta is 0.05% and that of rosemary oil 0.5%. The MIC values are independent on strain and temperature of growth, however the bactericidal effects are strain dependent. The addition of any of oil at a concentration equal to 2MIC to the modified atmosphere (80% O₂/20% CO₂) does not significantly influence the microbial quality of meat. At the same time, such a concentration of the essential oils was considerably detrimental to the organoleptic factors.     

The Efficiency of TBHQ, β-carotene, Citric Acid, and Tinuvin 234® on the Sensory Stability of Soybean Oil Packaged in PET Bottles

ABSTRACT: The use of plastic packaging for oils permits exposure to light, increasing oxidation. The goal of this work was to maximize sensory stability of soybean oil packaged in PET bottles. A central composite design was used to combine different levels of TBHQ, β‐carotene, and citric acid, added to oil, and Tinuvin 234®, added to bottles. After 6 mo of storage, the oxidation degree was assessed by sensory and peroxide tests. TBHQ and Tinuvin 234 were the most effective antioxidants, and the minimum concentrations required to keep a reasonable stability during storage were: 120 ppm of TBHQ; 7 ppm of β‐carotene; 15 ppm of citric acid and 0.1% of Tinuvin 234.