Quality of enoki mushrooms as affected by packaging conditions

Fresh enoki mushrooms (100 g) were packaged under various conditions and stored at 10 °C for 14 days. Package atmosphere, weight loss, stipe elongation, surface colour and sensory quality of the mushrooms were measured during storage. Different levels of initial vacuum application did not have a significant influence on the in‐package atmosphere after 2 days. The half‐vacuum package was best in terms of quality preservation of the fresh mushrooms. A polyolefin film with respective gas permeabilities of 166 and 731 ml m⁻² h⁻¹ atm⁻¹ to O₂ and CO₂ established an equilibrated atmosphere of 1.7–2.4% O₂ and 4.1–5.6% CO₂ inside the package at 10 °C. This polyolefin film was shown to contribute to preserving the freshness of the mushrooms. Temperature fluctuations between 5 and 15 °C did not induce a harmful atmosphere inside the polyolefin package, though high temperatures accelerated the quality loss. © 2000 Society of Chemical Industry     

Using polysaccharide-based edible coatings to maintain quality of fresh-cut Fuji apples

The effect of alginate and gellan-based edible coatings on the shelf-life of fresh-cut Fuji apples packed in trays with a plastic film of a known permeability to oxygen (110 cm³ O₂ m⁻² bar⁻¹ day⁻¹) was investigated by measuring changes in headspace atmosphere, color, firmness and microbial growth during 23 days of storage at 4 °C. Concentration of O₂ and CO₂ in the package was measured and no significant differences between coated and uncoated fresh-cut apples were observed. Ethylene concentration in coated apples seemed to be delayed since it remained below 50 μl l⁻¹ throughout the whole refrigerated storage period, while production of this gas was detected in uncoated apples from the very initial days of storage. Coated apple wedges exhibited ethanol and acetaldehyde formation from the second week of storage indicating fermentative metabolism. Polymers were crosslinked with a calcium chloride solution, to which the antibrowning agent N-acetylcysteine was added, being incorporated into the coatings formulation and helping to maintain firmness and color of apple wedges during the entire storage time. The application of the edible coatings also retarded the microbiological deterioration of fresh-cut apples. Alginate and gellan edible coatings effectively prolonged the shelf-life of Fuji apple wedges by 2 weeks of storage compared with the control apple slices which showed a considerable cut surface browning and tissue softening from the very early days of storage, limiting their shelf-life to less than 4 days.     

Sensory quality and internal atmosphere of fresh-cut Golden Delicious apples

The sensory shelf‐life of Golden Delicious fresh‐cut apples, dipped in 10 g L^?1 ascorbic acid and 5 g L^?1 calcium chloride and packaged under different modified atmosphere conditions, was assessed throughout refrigerated storage. An initial atmosphere of 0 kPa O₂ and plastic packages of an O₂ permeability of 15 cm³ m^?2 bar^?1 day^?1 were very effective in preserving the initial colour and firmness of apple cubes during at least 3 weeks of storage. These conditions resulted in increased respiration coefficients, which curbed the product consumer acceptance beyond the second week of storage. However, reduced ethylene and CO₂ production limited the appearance of fermentative metabolites during this period.     

Modified Atmosphere Packaging of Fresh, "Ready-to-use" Grated Carrots in Polymeric Films

“Ready-to-use” grated carrots were packaged in different films (oxygen permeability from 950 to 22,000 cc/m²/day/atm at 25°C) and stored at 2, 6 or 10°C for 10 days. Gaseous atmosphere in packs and the following were monitored: lactic acid bacteria, yeast counts, exudate and potassium ion released, sugars, carotene, ethanol and lactic acid. The respiration rate of the packaged carrots was measured. Films with very low oxygen permeability resulted in anaerobic respiration, high leakage of potassium, and high lactic acid bacteria. With high-permeability films (between 10,000 and 20,000 cc/m²/day/atm at 25°C), grated carrots showed aerobic respiration and retained good quality. At 10°C, in carrots packed in the most permeable film, sucrose decreased markedly during storage. The gas permeabilities required for packaging grated carrots were evaluated in relation to storage temperature.     

Development and Characterization of Biodegradable/Edible Wheat Protein Films

Biodegradable and edible films were prepared from three types of wheat flours: commercial bread, hard red winter, and soft white. Films were produced at two pH values (4 and 11) and tested for oxygen permeability as related to temperature. Films were also produced with a cross-linked agent and tested for tensile strengths. Oxygen permeability was 5.9 × 10^?20 to 18.5 × 10^?20 m³O₂ m m^?2 s^?1 Pa^?1 similar to values for commercial nylon. The oxygen permeability activation energy varied from 9.1 to 14.5 kcal mol^?1, depending on type of flour and pH did not affect oxygen permeability. Presence of the cross-linking agent increased the strength of films and elongation at break ranged from 490% to 640%, while tensile stress at break ranged from 25.8 × 10^?3 kg m^?2 to 44.1 × 10^?3 kg m^?2, lower than commercial nylon.     

OXYGEN TRANSMISSION RATE of an EDIBLE METHYLCELLULOSE-PALMITIC ACID FILM1

Edible coatings with low potassium sorbate permeability could be used to increase the microbial stability of food surfaces. However, such coatings could induce anaerobic food conditions if their oxygen permeability were low. the oxygen permeability of an edible emulsion film (average thickness, 55 μm), composed of methylcellulose and palmitic acid (weight ratio of 3:1), was evaluated at 24°C, atmospheric pressure, and at different percentages of relative humidity (RH). RH values in the 0–57% range had no significant effect on oxygen transmission rate (OTR); calculated OTR values ranged from 660 to 740 mL O₂ (STP)/m² 24h atm. At 79% RH, the OTR doubled to 1,500 mL O₂ (STP)/m² 24h atm. This effect correlated well with the moisture isotherm for the film which showed a low moisture content in the 0–57% RH range and a rapid increase at higher RH values. OTR values, particularly at high relative humidity, indicate no risk of developing anaerobic conditions on the food surface.     

Assessment of Relationships between Sensory and Instrumental Quality of Controlled-atmosphere-stored 'Fuji' Apples by Multivariate Analysis

ABSTRACT: Physicochemical parameters, sensory attributes, and total aroma emission of ‘Fuji’ apples (Malus×domestica Borkh.) were studied in relation to storage conditions, storage duration, and shelf life period. Commercially ripe fruit were analyzed after 3, 5, and 7 mo of cold storage in normal atmosphere (AIR) (210 L/m³ O₂+ 0.3 L/m³ CO₂) or under 3 different controlled atmosphere (CA) treatments (10 L/m³ O₂+ 10 L/m³ CO₂, 20 L/m³ O₂+ 20 L/m³ CO₂, or 10 L/m³ O₂+ 30 L/m³ CO₂), after which apples were kept at 20 °C for 1, 5, and 10 d. Data were subjected to partial least square regression (PLSR) analysis. Physicochemical parameters were well preserved throughout storage, especially in CA‐stored apples; however, these apples showed lower total aroma emission. Sensory acceptability was also higher for CA‐stored fruit after 7 mo of storage, whereas no significant differences were found for shorter storage periods. Accordingly, greater scores in sensory firmness, sensory flavor, sensory acidity, and appearance were observed for fruit stored in 10 L/m³ O₂+ 10 L/m³ CO₂ after long storage. Two PLSR models were established, 1 for relating physicochemical parameters to overall acceptability, and another for assessing the correlation between sensory acidity and instrumentally measured titratable acidity. The 1st PLSR model indicated that soluble solids concentration, titratable acidity, flesh firmness, and background color of the shaded side have a positive influence on acceptability. The 2nd model indicated that sensory acidity also showed an excellent correlation to instrumentally measured titratable acidity.     

Chitosan Film Mechanical and Permeation Properties as Affected by Acid, Plasticizer, and Storage

The effects of acid (acetic, formic, lactic, propionic) concentrations, plasticizer concentrations, and storage time (up to 9 wk) on mechanical properties, water vapor permeability, and oxygen permeability of solution-cast chitosan films were determined. Measured water vapor permeability coefficients ranged from 5.35 to 13.20 × 10^?1 g/m·day·atm. Oxygen permeated coefficients ranged from 0.08 to 31.67 × 10^?3 cc O₂ m·day·atm. Neither property was affected by storage time. Tensile strength (6.85–31.88 Mpa) also was not time dependent, but elongation (14–70%) decreased with storage time. Lactic acid solutions produced the lowest oxygen permeability values, formic acid the highest. Films formed with 7.5% lactic acid solutions had uniquely high values for elongation at break.     

Effect of minimal processing on the textural and structural properties of fresh‐cut pears

The feasibility of minimal processing and modified atmosphere packaging to preserve the original textural quality of fresh‐cut pears was evaluated throughout storage under refrigeration. Fresh‐cut pear firmness could be extended up to several weeks with low‐O₂ atmospheres. A packaging atmosphere of 100% N₂ combined with the use of plastic bags with an O₂ permeability of 15 cm³ m^?2 bar^?1 day^?1 maintained cell structure and partially avoided membrane breakdown and exudate accumulation in intercellular spaces. Under the other conditions studied, pear texture underwent dramatic deterioration, which could be related to complete inundation of the extracellular environment. Firmness decreased linearly throughout the storage period studied, with rate constants ranging from 0.0097 to 0.040 day^?1. The consideration of other textural variables also gave valuable information, similar to that provided by firmness data. © 2002 Society of Chemical Industry     

Relationships between volatile production,fruit quality and sensory evaluation of Fuji apples stored in different atmospheres by means of multivariate analysis

Aroma compounds, quality parameters and sensory characteristics of Fuji apples were analysed after 3, 5 and 7 months of storage at 1 °C in normal air (AIR; 210 l m^?3 O₂/0.3 l m^?3 CO₂) and in controlled atmospheres with O₂/CO₂ ratios of 10 l m^?3/10 l m^?3 (ULO1), 10 l m^?3/20 l m^?3 (ULO2) and 30 l m^?3/20 l m^?3 (SCA). After storage the apples were kept at 20 °C for 1, 5 and 10 days. The components that contributed most to the characteristic aroma of Fuji apples were ethyl 2‐methylbutanoate, 2‐methylbutyl acetate and hexyl acetate. The highest aroma compound production was found in ULO1 fruits after 5 months of cold storage and 1 day of shelf‐life. After 3 and 5 months of storage, ULO1 fruits showed the highest firmness after both 1 day and 10 days at 20 °C. After 7 months of storage plus 1 day at 20 °C, ULO2 fruits showed higher titratable acidity and soluble solid content; fruit firmness was also maintained throughout the shelf‐life period. Generally, background and superficial colour were not influenced by storage conditions. A statistically significant correlation was found between aroma compounds, quality parameters and sensory evaluation. Copyright © 2003 Society of Chemical Industry     

Effects of modified atmosphere packaging with different sizes of silicon gum film windows on Salicornia bigelovii Torr. storage

BACKGROUND: Salicornia bigelovii Torr. is a promising seasonal plant using seawater production but perishable with short shelf‐life under ambient conditions. To develop a modified atmosphere packaging (MAP) for extension of S. bigelovii shelf‐life, a nonselective polyethylene/polyamide (PE/PA) bag combining different sizes (0.6, 1.0 and 1.4 cm²) of silicon gum film (SGF) windows was tested, and low‐density polyethylene (LDPE) and perforated (1.0 cm²) PE/PA bags were used as controls. RESULTS: During 36 days of storage at 2 °C, the equilibrium compositions of O₂/CO₂ in LDPE, SGF1 (0.6 cm²), SGF2 (1.0 cm²) and SGF3 (1.4 cm²) were 3.0–5.0/4.5–6.5 kPa, 0.5–1.5/8.5–19.0 kPa, 2.5–5.0/5.5–10.0 kPa, and 6.0–13.0/4.0–6.5 kPa, respectively. Passive MAP treatments improved the quality attributes of S. bigelovii during initial storage; however, the 0.6 cm² SGF package markedly accelerated deterioration over the latter storage. The 1.0 cm² SGF package was observed to provide the optimal condition for S. bigelovii storage. CONCLUSION: The results show that passive MAP with optimized sizes of SGF windows could be an effective technique for prolonging shelf‐life of S. bigelovii. Copyright © 2009 Society of Chemical Industry     

Shelf life prediction of aluminum foil laminated polyethylene packed vacuum dried coconut milk powder

Shelf life of vacuum dried coconut milk powder packed in aluminum foil laminated polyethylene packages was predicted using developed mathematical models based on two limiting criteria viz., onset of caking and lipid oxidation. Accelerated storage studies for coconut milk powder packed in aluminium foil laminated polyethylene pouches were conducted at 90 ± 1% relative humidity and 38 ± 2 °C temperature. Threshold value for the shelf life prediction based on moisture migration was taken as the critical moisture content at which lump formation was observed. Shelf life prediction based on lipid oxidation involved establishing relationships between rate of oxygen absorption, package oxygen concentration, volume of O₂ absorbed, peroxide value of the powder and storage time. A peroxide value of 10 mEq. of O₂ per kg fat was considered as the threshold limit for oxidative rancidity. A good fit between experimental and predicted data with relative deviation percent below 10% was observed during storage studies.     

Use of passive and active modified atmosphere packaging to prolong the postharvest life of three varieties of apricot (Prunus armeniaca, L.)

The evolution of the atmospheric composition (O₂ and CO₂ and ethylene) passively produced by three varieties of apricots (Beliana, Rouge de Rousillon and Polonais) stored at 10 °C under four plastic films of different permeabilities was studied. The results corresponding to respiratory intensity (IR) revealed that, while the IR decreased during the storage period under modified-atmosphere packaging, it increased again with the opening of the bags and the exposure of the fruits to air. The modified atmosphere inside the bags (O₂ and CO₂) and the time necessary to reach equilibrium depended on the IR of the fruits and the permeability of the film. The ethylene concentration decreased from the second day onwards in all the cases studied; this decrease being more pronounced in the films of least permeability due to a combination of its diffusion through the film and the inhibition of its synthesis as the CO₂ concentration increased and O₂ concentration decreased. Partial deviations in the metabolism of the three varieties were detected in the two films of lowest permeability (6060 and 12100 cm³ of O₂ and CO₂ m⁻²/24 h⁻¹ atm⁻¹ at 25°C) due to anoxia. The use of the active modified atmosphere, replacing the initial atmosphere of the bags with an atmosphere enriched with CO₂ (20% CO₂ and 80% air), did not modify the gas composition at equilibrium, although it shortened the time necessary for it to be reached. For the Beliana variety a slight decrease in ethylene concentration was observed inside the bags with an active modified atmosphere in relation to that of the bags with a passive modified atmosphere. The accumulation of ethanol in the tissues was not higher under the active modified atmosphere than under the passive modified atmosphere. Received: 19 July 1999 / Revised version: 29 September 1999     

PACKAGING PRESERVATION OF β-CAROTENE IN SWEET POTATO FLAKES USING FLEXIBLE FILM AND AN OXYGEN ABSORBER

Sweet potato flakes are potentially an affordable, shelf-stable source of provitamin A β-carotene. Because β-carotene is susceptible to oxidative degradation, particularly in dehydrated food materials exposed to atmospheric oxygen, several packaging conditions were evaluated for enhancement of β-carotene retention in sweet potato flakes during storage. The flakes were packaged in either a polypropylene film (high oxygen permeability) with air headspace or a nylon laminate film (low oxygen permeability) with air headspace, under vacuum, or with an Ageless oxygen absorber sachet enclosed. Packaged flakes were stored in the dark at ambient laboratory temperature (～23C), and β-carotene content was determined at intervals from 0 to 210 day storage using reversed-phase liquid chromatography. Among the packaging conditions tested, β-carotene retention was enhanced incrementally as the apparent availability of oxygen was reduced (nylon > polypropylene; oxygen absorber > vacuum > air headspace). The combined use of oxygen absorbers and flexible oxygen barrier film gave excellent retention of β-carotene during the 210 day trial.     

Evaluation of Changes in Listeria monocytogenes Populations on Frankfurters at Different Stages from Manufacturing to Consumption

ABSTRACT: This study evaluated the fate of inoculated Listeria monocytogenes on frankfurters stored under conditions simulating those that may be encountered between manufacturing and consumption. Frankfurters with or without 1.5% potassium lactate and 0.1% sodium diacetate (PL/SD) were inoculated (1.8 ± 0.1 log CFU/cm²) with a 10‐strain composite of L. monocytogenes, vacuum‐packaged, and stored under conditions simulating predistribution storage (24 h, 4 °C), temperature abuse during transportation (7 h, 7 °C followed by 7 h, 12 °C), and storage before purchase (60 d, 4 °C; SBP). At 0, 20, 40, and 60 d of SBP, samples were exposed to conditions simulating delivery from stores to homes or food establishments (3 h, 23 °C), and then opened or held vacuum‐packaged at 4 or 7 °C for 14 d (SHF). Pathogen counts remained relatively constant on frankfurters with PL/SD regardless of product age and storage conditions; however, they increased on product without antimicrobials. In vacuum‐packaged samples, during SHF at 4 °C, the pathogen grew faster (P < 0.05) on older product (20 d of SBP) compared to product that was fresh (0 d of SBP); a similar trend was observed in opened packages. At 7 °C, the fastest growth (0.35 ± 0.02 log CFU/cm²/d) was observed on fresh product in opened packages; in vacuum‐packages, growth rates on fresh and aged products were similar. By day 40 of SBP the pathogen reached high numbers and increased slowly or remained unchanged during SHF. This information may be valuable in L. monocytogenes risk assessments and in development of guidelines for storage of frankfurters between package opening and product consumption.     

QUALITY OF PRECOOKED VACUUM-PACKED POTATOES (Solanum tuberosum L.) IN RELATION TO COOKING METHODS AND OXYGEN PERMEABILITY OF THE PACKAGING MATERIAL

Precooked vacuum-packed potatoes are widely used in catering. The influence of different processing temperatures on texture kinetics of water and steam cooked vacuum-packed potatoes was studied. At temperatures above 90C the initial decline in cohesion of steam cooked vacuum-packed potatoes was followed by an increase in cohesion when processed for more than 30 min. Preheating of vacuum-packed potatoes at 70C and 75C increased their cohesion and thereby firmness. Steam cooked vacuum-packed potatoes processed in multilayer barrier pouches having a low oxygen permeability (0.9 cm³/m²/24h/atm) compared with standard pouches had a more intense and stable yellow surface color, as well as they developed significantly less off-flavor after storage. The oxygen permeability of the pouches had no effect on the content of vitamin C, neither during processing nor after storage. The vitamin C content of steam cooked vacuum-packed potatoes was unaffected by processing time.     

Physical and Mechanical Properties of Biobased Materials Starch,Polylactate and Polyhydroxybutyrate

Commercial and semi‐commercial biobased materials (Polylactate, PLA, polyhydroxy‐butyrate, PHB, wheat starch and corn starch) were investigated. Physical and mechanical characterisation (tensile strength, elongation, tear strength, compression, gas permeability (CO₂ and O₂) and water vapour permeability (WVP)) was examined. Tests on both films and cups show potential use of these materials for primary food packaging, especially PLA and PHB. An interesting O₂:CO₂ permeability ratio (1:7 to 1:12) was seen, which make these materials suitable for packaging of food with high respiration. The mechanical properties were comparable to conventional materials such as polyethylene (PE) and polystyrene (PS). The WVP measured on films ranged from 12.6 to 18.6 [g H₂O/(m² ? 24h)], and on cups the range was 2.2 to 10.5 [g H₂O ? 700 μm/(m² ? 24h)]. The WVP for the starch‐based materials seems to be the most crucial parameter, and needs improvement if these materials are to be used as food packaging.     

Impact of slicing hygiene upon shelf life and distribution of spoilage bacteria in vacuum packaged cured meats

A model for studying spoilage in sliced cooked delicatessen meats using conventional plating procedures was characterized by following the transfer of adventitious lactic acid bacteria (LAB), thermotolerant LAB and pediococci from a dry fermented sausage to cooked ham and bologna during a simultaneous slicing procedure. The major group of organisms present in these products was LAB. Each of the three groups of organisms was transferred to the cooked meats, but during storage under vacuum at 7°C, only the adventitious lactobacilli from the sausage appeared to contribute to cooked meat spoilage. Pediococci declined within 28 days of co-slicing, thermotolerant LAB grew slowly and never reached levels of >5 log₁₀cfu cm⁻², but transferred adventitious LAB from the sausage grew and reached peak populations 4 weeks earlier in the co-sliced cooked meats than in controls. During storage at 7°C co-sliced cooked meats spoiled, as assessed by purge (liquid) and ropy slime formation, 2–4 weeks faster than the separately-sliced and vacuum-packaged products. The distribution of organisms on package slices differed. In control cooked products numbers of bacteria present on center package slices were lower than on outside slices. Bacterial numbers were greatest at the meat surface–packaging film interface. In co-sliced cooked products organisms were evenly distributed throughout slices in the packages. Based on findings from use of the co-slice model, in vacuum packages of sliced cured meats where >10⁵cfu bacteria cm₋₂are equally distributed throughout package slices, poor slicing hygiene is the cause. Commercially-sliced bologna was repackaged with allyl isothiocyanate (AIT) to test its ability to delay bacterial growth at the meat surface. The preservative effects of AIT were tested under vacuum or when backflushed with CO₂. CO₂alone was more effective than AIT in delaying LAB growth but neither treatment was particularly effective.     

Thermal transition and thermo-physical properties of potato (<Emphasis Type="Italic">Solanum tuberosum L</Emphasis>.) var. Russet brown

Potatoes are an important food in many regions of the world and are commonly used in a variety of food products. Thermal transition and thermo-physical properties of potatoes are important in order to design efficient food processes and select appropriate storage conditions. In this study, we determined the thermal transitions and thermophysical properties of raw and blanched/par-fried potato for a temperature range of ??32 to 21.1 °C. Using differential scanning calorimetry, we found an initial freezing point (T_f) at ??1.8?±?0.1 °C, an onset of melting (T_m^′) at ??9.9?±?0.2 °C and an unfreezable water content (X^′_w) for maximally freeze-concentrated raw potato at 0.21 kg water/kg potato. Corresponding values for blanched/par-fried potatoes were ??0.9?±?0.1 °C, ??11.0?±?0.2 °C and 0.18 kg water/kg potato. Results show that an increase in solids content decreased T_f of both raw and blanched potatoes. We modelled the relationship between them using the Chen model. The apparent specific heat (C_app) increased around T_f to 31.7?±?1.13 kJ/kg K for raw potato and 26.7?±?0.62 kJ/kg K for blanched/par-fried potato. For frozen raw potato at ??32 °C, thermal diffusivity (α) was 0.89?±?0.01?×?10?^?6 m²/s and thermal conductivity (k), 1.82?±?0.14 W/m K, respectively. These values were higher for frozen raw potato than for the unfrozen raw potato (0.15?±?0.01?×?10?^?6 m²/s and 0.56?±?0.08 W/m K, respectively at 21.1 °C). The apparent density (ρ) of frozen raw potato (992?±?4.00 kg/m³ at ??32 °C) was less than that for unfrozen raw potato (1053?±?4.00 kg/m³ at 21.1 °C), and a similar trend was obtained for blanched/par-fried potato (993?±?2.00 kg/m³ at ??32 °C and 1188?±?7.00 kg/m³ at 21.1 °C, respectively). This study established a correlation between thermo-physical properties and temperature. Findings may be used to inform the design and optimization of freezing processes and frozen storage for potato products.     

Effect of the ripening time under vacuum and packaging film permeability on processing and quality characteristics of low-fat fermented sausages

The effect of vacuum ripening of low-fat fermented sausages packaged in films with different permeabilities on their microbiological, physicochemical and sensorial characteristics was studied. High-fat control sausages were produced with 30% initial fat and low-fat sausages with 10% initial fat. The low-fat sausages were separated into: (a) non-packaged (control) and (b) packaged under vacuum on 7th, 12th and 17th day of processing, remaining under vacuum during the ripening period for 21, 16 and 11 days, respectively, in three different oxygen (100, 38 and ? 5 cm³/m²/24 h/1 atm) and water vapour (4.5, <2.5 and 1 g/m² 24 h) permeability plastic bags. Vacuum packaging reduced (p < 0.05) the weight loss, the hardness and extent of lipid oxidation in the sausages, increased (p < 0.05) their lightness, but had no effect (p > 0.05) on the redness, compared to the control sausages. Packaging low-fat fermented sausages under vacuum for the last 11 days of ripening in packaging film with high permeability increased (p < 0.05) the lactic acid bacteria count. The same product packaged in film with medium permeability had a higher (p < 0.05) Micrococcaceae count and the same (p > 0.05) hardness and overall acceptability as the high-fat control sausages. A ripening time of 11 days and the medium packaging film permeability were the most appropriate conditions for the vacuum packaging of low-fat fermented sausages.