Influence of flavour absorption on oxygen permeation through LDPE, PP, PC and PET plastics food packaging

The effect of flavour absorption on the oxygen permeability of low-density polyethylene (LDPE), polypropylene (PP), polycarbonate (PC) and polyethylene terephthalate (PET) was studied using an isostatic continuous flow system. Polymer samples were exposed to a model solution containing limonene, hexyl acetate, nonanone and decanal at 40°C. After exposure, one part of each sample was analysed for absorbed flavour compounds using a Large Volume Injection GC Ultrasonic 'in vial' extraction method, and from the other part, oxygen permeability was measured in a permeation cell at 25°C. After 8h of exposure, LDPE and PP samples showed a significant linear (R² = 0.82 and 0.99) increase in oxygen permeability of 21 and 130%, respectively. Owing to swelling of the polymer samples resulting from flavour absorption, the structure of the polymeric network changed (i.e. opened) and consequently increased oxygen permeability. The oxygen permeability of exposed PC showed a significant linear (R² = 0.78) decrease of 11% after 21 days. PC obviously did not swell like LDPE or PP. Therefore, it was suggested that absorbed flavour compounds occupied or blocked 'microcavities' through which normally oxygen is transported. Absorption of flavour compounds by PET did not affect the oxygen permeability of PET significantly.     

Absorption of Aroma Volatiles of Orange Juice into Laminated Carton Packages Did Not Affect Sensory Quality

Orange juice was stored in glass bottles and polyethylene/barrier material laminated cartons at 4°C for 24 wk. Studies were carried out on the absorption of 19 orange juice aroma compounds (e.g ethyl butyr-ate, d-limonene) into low density polyethylene (LDPE). Sensory evaluations were performed on the same orange juice in different packages over the storage period. A reduction of d-limonene of up to 50% by absorption into the LDPE inside coating was observed. However, an experienced sensory panel did not distinguish between orange juice stored in glass bottles and polyethylene laminated cartons.     

Evolution of aroma compounds from orange juice stored in polyethylene terephthalate (PET).

The evolution of aroma compounds from orange juice made from concentrate and stored in glass, standard monolayer polyethylene terephthalate (PET 1), multilayer PET (PET 2) and plasma-treated PET (internal carbon coating) (PET 3) was investigated. Bottles were stored at room temperature (20 degrees C) under artificial light. Volatile compounds in orange juice samples and corresponding packaging materials were analysed at zero time and after 2, 3 and 5 months of storage. After 5 months of storage, from 0.2 to 0.3% of the initial amounts of limonene and beta-myrcene in the orange juice had been absorbed by the plastic packaging materials. Statistical analyses showed that the evolution of aroma compounds was strongly correlated to the duration of storage, but not to the type of packaging material. Indeed, whatever the stored orange juice samples, the same evolutions were observed, with a decrease in aldehydes and ketones, esters, aliphatic alcohols, sesquiterpene and monoterpene alcohols, and an increase in two aliphatic and monoterpene alcohols (i.e. furfural and 4-vinylguaicol). The results suggest that the losses of aroma compounds from the juice could be attributed to the high acidity of the matrix, implying acid-catalysed reactions. Finally, PET packaging materials and their corresponding oxygen permeabilities showed no correlation with the loss of aroma compounds.     

Influence of Storage Time and Temperature on Absorption of Flavor Compounds from Solutions by Plastic Packaging Materials

ABSTRACT: Linear low-density polyethylene (LLDPE), oriented polypropylene (OPP), polycarbonate (PC), polyethylene terephthalate (PET film and PET bottle), and polyethylene naphthalate (PEN) were stored in a model solution containing 10 flavor compounds at 4, 20, and 40 °C and flavor absorption by the plastic materials was followed in time. The absorption rate and/or total amount absorbed increased considerably with temperature from 4 to 40 °C. Depending on storage temperature, total flavor absorption by the polyolefins (LLDPE and OPP) was 3 to 2400 times higher than by the polyesters (PC, PET, and PEN). Therefore, in the factor of flavor absorption, polyesters are preferred over polyolefins as packaging material.     

Orange Flavor Absorption Into Various Polymeric Packaging Materials

Citrus oil components (from cold-pressed and terpeneless oils), which contribute substantially to flavor of orange juice, were shown to be absorbed into various polymeric materials [low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP), and surlyn (S)] used in aseptic packaging. Equilibration of absorption took place within 4 days, while extraction of the oil constituents occurred in 24 hr when higher temperatures were used. Substantial absorption of oil constituents by LDPE and S occurred while highly crystalline polymers (PP and HDPE) did not absorb much. The degree of absorption also depended on the nature of the oil constituents. Absorption was higher for terpene constituents followed by sesquiterpenes and aldehydes. Swelling factors showed that highly crystalline polymers (HDPE and PP) swelled less than crystalline polymeric materials. Citrus oil affected the crystallinity of the polymers by lowering their melting point and percent crystallinity.     

Effects of pulsed electric field processing and storage on the quality and stability of single-strength orange juice

The effects of pulsed electric field (PEF) processing on microorganisms in orange juice and on the flavor and color of the juice during storage for 112 days at 4 and 22 degrees C were investigated. Single-strength orange juice was PEF processed at an electric field strength of 35 kV/cm for 59 micros and placed into sterilized glass bottles in a sanitary glove box. PEF-processed orange juice was microbiologically stable at 4 and 22 degrees C for 112 days. PEF processing resulted in significant increases in the hydrocarbons D-limonene, alpha-pinene, myrecene, and valencene (P < or = 0.05) but did not have any effect on octanal, decanal, ethyl butyrate, and linalool. The levels of hydrocarbon compounds did not change at 4 and 22 degrees C in 112 days. Octanal, decanal, ethyl butyrate, and linalool levels significantly decreased in 14 days at 4 degrees C and in 2 days at 22 degrees C. The decrease in these compounds did not have a significant effect on the sensory quality of the orange juice (P > or = 0.05). The microorganisms in PEF-processed orange juice, along with the flavor and color of the juice, remained stable at 4 degrees C for 112 days.     

Flavor Losses in Orange Juice during Ultrafiltration and Subsequent Evaporation

Losses of volatile compounds in orange juice during ultrafiltration and subsequent evaporation were studied. Alcohols and esters predominated in the permeate, while terpenes (d-limonene and valencene) and nonpolar aldehydes (octanal and decanal) were distributed in the retentate from the ultrafiltration (UF) system. Fractions of some flavor compounds were lost during ultrafiltration process. An aqueous phase essence was recovered from the permeate during evaporative concentration. No oil phase was observed. When whole juice was concentrated, both oil and aqueous phases were recovered. Essence recovery efficiency of individual compounds was 3 to 13% when concentrating permeate and <5% when concentrating whole juice.     

Influence of food matrix on absorption of flavour compounds by linear low‐density polyethylene: proteins and carbohydrates

The effects of differences in food matrices on the absorption of four flavour compounds (limonene, decanal, linalool and ethyl 2‐methyl butyrate) into linear low‐density polyethylene (LLDPE) were studied using a large volume injection GC ‘in vial’ extraction method. Food components investigated included β‐lactoglobulin (β‐lg), casein, pectin, carboxymethylcellulose (CMC), lactose and saccharose. β‐lg interacted irreversibly with decanal (P < 0.01) and suppressed absorption of the latter by LLDPE by more than 50% after 14 days of exposure. Casein was capable of binding limonene and decanal (p < 0.05) by hydrophobic and covalent interactions, resulting in decreased absorption of 40% and 90%, respectively. The absorption rates of limonene, and to a leaser extent decanal, were decreased in presence of pectin and CMC. Increasing viscosity slowed down diffusion of flavour compounds from the matrix to LLDPE. An increase of absorption (p < 0.01) was observed for linalool and ethyl 2‐methyl butyrate, due to a ‘salting out’ effect caused by lactose and saccharose. The absorption of decanal was decreased (p < 0.01) after 14 days of exposure in the presence of lactose, saccharose and CMC. There might be an interactive effect between a sugar (residue) and decanal. Knowledge of the composition of a food matrix and packaging material is necessary to estimate the amount of flavour absorption. © 2000 Society of Chemical Industry     

Influence of PET and PET/PEN Blend Packaging on Ascorbic Acid and Color in Juices Exposed to Fluorescent and UV Light

ABSTRACT: Apple and orange juices packed in polyester bottles were stored in dark, intense fluorescent (1500 lux), and UV light conditions in temperature-controlled (22 °C) chambers and monitored more than 7 mo for ascorbic acid content and color changes. Polyester beverage bottles were made of polyethylene terephthalate (PET), or PET blended with 0.25%, 1%, and 4% polyethylene naphthalate (PEN). The cut-off wavelength ranged from 322 nm for PET to 373 nm for the 4% PEN/PET blend. Spectral irradiance, visible light intensity, and light distribution were evaluated in the light chambers and compared with supermarket display lighting and outdoor daylight conditions. Only the UV chamber and sunlight showed significant irradiance at wavelengths below 400 nm. Ascorbic acid (AA) degradation and concurrent color changes occurred in both juices during storage in all 3 lighting conditions and in all 4 bottle types. Zero-order reaction kinetics described the AA degradation rate for all treatments. Apple juice stored in UV had a significantly higher ( P < 0.05) AA degradation rate than juice stored in the dark or in fluorescent light. Under UV conditions, apple juice in PET/ PEN bottles had a lower AA degradation rate than the juice in PET bottles. AA degradation in orange juice was less affected by UV exposure than in apple juice. Both juices darkened over time when stored in dark and fluorescent conditions, whereas UV exposure caused some initial bleaching of color before darkening. The bleaching effect was reduced in apple juice stored in the PET/PEN bottles.     

分子蒸馏法富集甜橙油特征香气成分

采用分子蒸馏法(短程分子蒸馏器)富集甜橙精油中的特征香气成分,如癸醛、辛醛、芳樟醇及巴伦西亚桔烯等,同时采用气相色谱-质谱联用法进行检测。通过各参数优化比较,最终确定分子蒸馏条件为温度30℃、压力150Pa、转速200r/min、流速8mL/min。在此条件下,各成分富集结果为辛醛(由0.46%提高到1.55%)、癸醛(由0.59%提高到9.11%)、芳樟醇(由0.71%提高到5.84%)、巴伦西亚桔烯(由0.24%提到高7.96%)。分子蒸馏技术可用于甜橙油特征香气成分的高效富集。     

Sorption of flavour compounds in aqueous solution into polyethylene film

Sorption of flavour compounds by the polyethylene (PE) liner of laminated pouches (PET/Al/PE) containing a flavour solution has been studied. The solution contained 43 volatile compounds (each 2 μl litre^?1) in sugar ester solution (3 g litre^?1). The distribution ratios of the flavour compounds for sorption into various PE liners increased with carbon chain length of the flavour compounds from 0.01 to 0.1 for alcohols, from 0.03 to 1.23 for aldehydes, from 0.02 to 5.77 for aliphatic esters and from 0.11 to 11.6 for benzoates. In each series (all straight-chain compounds) the distribution ratios increased about threefold for each methylene group, but in the compounds composed of 11 or more carbon atoms the increment was less or negative. The distribution ratio for a given PE film was proportional to the film thickness. The distribution ratios increased with decreasing crystallinity of the PE film and the results for the films of different crystallinities suggested the existence of an impermeable boundary region surrounding the crystalline material amounting to about 20% of its volume.     

甜橙键合态芳香组分的酶(酸)解解离方法研究

以甜橙为研究对象 ,通过采用AmberliteXAD 2树脂吸附溶剂解吸法 ,对橙汁的游离态与键合态芳香组分进行分离 ,然后酶 (酸 )解键合态组分 ,释放橙汁中的潜在芳香组分。通过对酶 (酸 )解反应方式释放的芳香组分的比较 ,确定适宜的解离方法     

Radiolysis products and sensory properties of electron-beam-irradiated high-barrier food-packaging films containing a buried layer of recycled low-density polyethylene

The aim was to study the effect of electron-beam irradiation on the production of radiolysis products and sensory changes in experimental high-barrier packaging films composed of polyamide (PA), ethylene-vinyl alcohol (EVOH) and low-density polyethylene (LDPE). Films contained a middle buried layer of recycled LDPE, while films containing 100% virgin LDPE as the middle buried layer were taken as controls. Irradiation doses ranged between zero and 60 kGy. Generally, a large number of radiolysis products were produced during electron-beam irradiation, even at the lower absorbed doses of 5 and 10 kGy (approved doses for food ‘cold pasteurization’). The quantity of radiolysis products increased with irradiation dose. There were no significant differences in radiolysis products identified between samples containing a recycled layer of LDPE and those containing virgin LDPE (all absorbed doses), indicating the ‘functional barrier’ properties of external virgin polymer layers. Sensory properties (mainly taste) of potable water were affected after contact with irradiated as low as 5 kGy packaging films. This effect increased with increasing irradiation dose.     

Characterisation of the key aroma compounds in a freshly reconstituted orange juice from concentrate

Application of an aroma extract dilution analysis on the entire volatile fraction isolated from an orange juice freshly reconstituted from concentrate revealed 40 odour-active constituents in the flavour dilution (FD) factor range of 4–2,048. Among them, ethyl butanoate and linalool showed the highest FD factor of 2,048, followed by octanal with an FD factor of 512. Thirty-six of the 40 odour-active compounds detected could be identified, all of which have previously been reported as volatile constituents of various orange juices. Quantification of 17 key odorants by stable isotope dilution assays followed by a calculation of odour activity values (OAVs) on the basis of odour thresholds in water or citrate buffer (pH 3.8), respectively, revealed the following most important odorants in the overall aroma of the freshly reconstituted juice: (R/S)-linalool, (R)-limonene and (S)-ethyl 2-methylbutanoate with the highest OAVs (>1,000) followed by octanal, (R)-α-pinene, ethyl butanoate, myrcene, acetaldehyde, decanal and (E)-β-damascenone with OAVs > 100. A model mixture containing all 14 aroma compounds with OAVs > 1 in their actual concentrations in the juice showed a good similarity with the aroma of the original orange juice under investigation, thus corroborating that the key odorants of a freshly reconstituted orange juice were characterised for the first time.     

Ascending bubble extraction of terpenes from freshly squeezed orange juice

Terpene hydrocarbons are volatile compounds that cause aromatic deterioration of orange juice during prolonged storage. In this study, we attempted to remove terpene hydrocarbons from the freshly squeezed orange juice using an ascending bubble extraction that allowed the bubbles of nitrogen at atmospheric pressure to pass through the juice. Remaining percentages of volatile concentrations were determined by gas chromatography. d-Limonene was used as a representative of terpene hydrocarbons because of its abundance. Linalool, octanal and decanal which are necessary volatiles for orange juice were also determined the remaining percentages. The ascending bubble extraction was the effective method for removing terpene hydrocarbons from the orange juice. The concentration of d-limonene was reduced as the increases of treatment time and temperature. After the extraction at 40 °C for 60 min, d-limonene was thoroughly removed from the orange juice while linalool and decanal remained approximately 80% and 45%, respectively.     

Isolation and Biological Activities of Decanal,Linalool, Valencene,and Octanal from Sweet Orange Oil

Abstract: Product 1 (82.25% valencene), product 2 (73.36% decanal), product 3 (78.12% octanal), and product 4 (90.61% linalool) were isolated from sweet orange oil by combined usage of molecular distillation and column chromatography. The antioxidant activity of sweet orange oil and these products was investigated using 2,2‐diphenyl‐1‐picrylhydrazyl and reducing power assays. In this test, product 1 (82.25% valencene), product 2 (73.36% decanal), and product 4 (90.61% linalool) had antioxidant activity, but lower than sweet orange oil. The antimicrobial activity was investigated in order to evaluate their efficacy against 5 microorganisms. The results showed that sweet orange oil, product 2 (73.36% decanal), product 3 (78.12% octanal), and product 4 (90.61% linalool) had inhibitory and bactericidal effect on the test microorganisms (except Penicillium citrinum). Valencene did not show any inhibitory effect. Saccharomyces cerivisiae was more susceptible, especially to the crude sweet orange oil (minimal inhibitory concentration 6.25 μL/mL). The cytotoxicity was evaluated on Hela cells using the 3‐(4,5‐dimethyl‐thiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide assay. All test samples showed significant cytotoxicity on the cell lines with IC₅₀ values much less than 20 μg/mL.     

Anthocyanin infused watermelon rind and its stability during storage

Anthocyanins from Garcinia indica Choisy was impregnated in watermelon rind (WMR) through osmotic dehydration. The impregnation of anthocyanin was enhanced by application of pretreatments like vacuum and sonication (from 24 to 32 mg/100 g). Application of pretreatment during impregnation changes the tissue architecture of the WMR which helps in retaining the infusate during candy making process. The developed product from WMR was highly acceptable w.r.t. texture, taste and appearance. Moisture sorption study indicated that the WMR product was quite stable at ambient temperature upto 75% RH. Storage of the sample in LDPE (low density polyethylene pouches) and PET/LDPE (Polyethylene terephthalate/low density polyethylene pouches) did not show any significant difference in moisture content, anthocyanin degradation, texture, taste and appearance of the product. The WMR product was stable for 90 days at ambient storage conditions.Industrial relevanceThe knowledge provided by this work may be useful the development of new product (watermelon candy) from watermelon rind impregnated with anthocyanin. The extent and rate of infusion of anthocyanin was enhanced by application of pretreatments like vacuum and sonication. The developed product had highly acceptable texture, taste and appearance. The product was quite stable at ambient temperature upto 75% RH in LDPE (low density polyethylene pouches) and PET/LDPE (Polyethylene therapthalate/low density polyethylene pouches) pouches without significant difference in moisture content, anthocyanin degradation, texture, taste and appearance of the product. The WMR product was stable for 90 days at ambient storage conditions. This technique may be helpful in producing foods with enriched bioactive compounds, besides providing diversified products in terms of taste and nutrition.     

Altered Oxygen Permeation Through Packaging Polymers in Contact with Liquids—a Mathematical Model Confirmed in a Dilute Xanthan Gum Solution

The ability of liquids to reduce oxygen permeation through low density polyethylene (LDPE), oriented polypropylene (OPP), polyethylene terepthalate (PET), and polyvinylidene chloride (PVTDC) films was mathematically modeled using a water/xanthan solution as a model medium. For low barrier films (LDPE and OPP), the medium substantially reduced oxygen permeation. In PET, an intermediate barrier, the medium produced a recognizable, but minor reductions in permeation. For the highest barrier (PVDC), the medium's influence on permeation was almost unidentifiable. The effect of the medium's oxygen solubility constant and diffusion coefficient on permeation was also examined. For all films, reduction in permeation became significant only after solubility and diffusion values fell below 40% of water values.     

脐橙果汁与果酒香气成分的GC-MS分析

采用溶剂萃取法分别提取脐橙果汁和经发酵后的果酒中的香气成分,经气相色谱质谱联用仪(GC-MS)分析,从果汁中鉴定出19种成分,占峰面积的83.5％,香气成分主要为苯乙醇、4-羟基-苯乙醇3-甲基-1-丁醇、D-柠檬烯、2,3丁二醇、巴伦西亚桔烯、亚油酸、油酸等:从果酒中鉴定出30种成分,占峰面积的91.13％,主要香气成分为苯乙醇、3-甲基-1-丁醇、d-柠檬烯、2,3丁二醇、乙酸乙酯、香叶醇、棕榈酸乙酯、3-乙氧基-1-丙醇、巴伦西亚桔烯、吲哚-3-乙醇、乙酸戊酯等.     

Volatile and non-volatile radiolysis products in irradiated multilayer coextruded food-packaging films containing a buried layer of recycled low-density polyethylene.

The effects of gamma-irradiation (5-60 kGy) on radiolysis products and sensory changes of experimental five-layer food-packaging films were determined. Films contained a middle buried layer of recycled low-density polyethylene (LDPE) comprising 25-50% by weight (bw) of the multilayer structure. Respective films containing 100% virgin LDPE as the buried layer were used as controls. Under realistic polymer/food simulant contact conditions during irradiation, a large number of primary and secondary radiolysis products (hydrocarbons, aldehydes, ketones, alcohols, carboxylic acids) were produced. These compounds were detected in the food simulant after contact with all films tested, even at the lower absorbed doses of 5 and 10 kGy (approved doses for food preservation). The type and concentration of radiolysis products increased progressively with increasing dose. Generally, there were no significant differences in radiolysis products between samples containing a buried layer of recycled LDPE and those containing virgin LDPE (all absorbed doses), indicating the good barrier properties of external virgin polymer layers. Volatile and non-volatile compounds produced during irradiation affected the sensory properties of potable water after contact with packaging films. Taste transfer to water was observed mainly at higher doses and was more noticeable for multilayer structures containing recycled LDPE, even though differences were slight.