The effects of packaging film and storage temperature on the quality of a dry coleslaw mix packaged in a modified atmosphere

Summary The effects of six packaging treatments on the quality of dry coleslaw packaged in modified atmospheres and stored at 4 and 8 °C for 9 days were determined. The coleslaw was packaged within either oriented polypropylene (OPP) or one of four microperforated OPP films, PA‐120, PA‐160, PA‐190, and PA‐210. It was also stored within punctured OPP (i.e. in air). Packaging within OPP resulted in an atmosphere with very low O₂ (<1%) and extremely high CO₂ (25–35%) levels. These storage conditions had detrimental effects on the quality of coleslaw: loss of firmness, falling pH, high cell permeability and exudate, high surface moisture and poor acceptability of aroma. By contrast, the microperforated films generated less atmosphere modification; in some cases this was insufficiently modified to be technically useful. The relatively high O₂ levels in these microperforated packs resulted in lower appearance and colour scores, increased surface dryness and higher firmness values. Increasing storage temperature from 4 to 8 °C resulted in a reduction in shelf‐life for all film types. While still not optimal, packaging within microperforated films allowed better preservation of quality and reduced cell membrane damage.     

Sensory effects of hexanal vapor on fresh-cut slices of golden delicious apples

Hexanal is a natural antimicrobial molecule that characterizes apples aroma. In this paper, the sensory effects of hexanal, as a component of packaging atmosphere, on fresh sliced Golden Delicious apples after storage at 4 °C for 8 d were evaluated. In particular, a colorimetric analysis of slices treated with different concentrations of hexanal vapor (coming from 3.040 to 0.076 mmol of liquid aldehyde per liter of air) fixed at 0.076 mmol/L the amount of hexanal in evaluating sensory effects in the subsequent analysis. Color and texture evaluation of slices by Two-out-of-Five method did not highlight any significant difference between treatment and control. The results from olfactory evaluation showed instead that treated samples had an intense odor compared with those untreated (P < 0.001). A significant difference between treatment and control was also highlighted during the flavor evaluation (P < 0.01); however, from the panelists' observations it emerged that such an effect would work negatively. The positive effect of the tested dose of hexanal on the odor of Golden Delicious slices and its flavor acceptability were verified by using regular apple consumers. A significant preference (P < 0.001) for the odor of treated apple slices came out, so the small dose of hexanal intensifies the odor of apples pleasantly. The different flavor of treated samples was not identified by the consumers, who altogether expressed positive judgments about it. This suggests the nicety of this difference that in the absence of an untreated reference sample is very difficult to detect.     

The effect of edible coatings and polymeric packaging films on the quality of minimally processed carrots

Minimally processed carrots have a short shelf‐life because of white blush formation (caused primarily by surface dehydration) and microbiological spoilage (caused mostly by lactic acid bacteria). The use of polymeric packaging films combined with edible coatings might have an additive or synergistic effect to extend the shelf‐life of minimally processed carrots because of the formation of a double barrier to gases and water vapour. A 3 × 3 factorial experiment using a polymeric packaging film of three different levels of permeability and a cellulose‐based edible coating (Nature Seal^®) at different concentrations was conducted on minimally processed carrots to investigate any possible synergistic effect over 12 days of storage at 10 °C. No such effect was found. The polymeric packaging film effectively prevented microbiological growth and spoilage but was unable to control white blush formation. On the other hand, the edible coating partially controlled white blush formation but enhanced microbiological spoilage. The polymeric packaging film functioned primarily as a gas barrier, whereas the edible coating probably functioned as a moisture barrier. White blush formation was found to be the most important shelf‐life determinant for minimally processed carrots. Copyright © 2003 Society of Chemical Industry     

Influence of Packaging Films on the Sensory and Microbiological Evolution of Minimally Processed Borage (Borrago officinalis)

The atmospheres prevalent in borage packaged in 5 different films, together with different water‐vapor permeabilities of the films, determined the evolution of the visual and microbiological quality of borage. PVC films proved inadequate to extend the sensory quality since the samples packaged with the films were spoiled on day 9, whereas among the P‐Plus films, the least permeable film was the most adequate to extend the sensory quality of borage until day 15. For most of the treatments, no correlation between the microbial growth and changes in appearance was found. Thus, some treatments with a fair sensory evaluation had microbial counts higher than those allowed by the European legislation.     

Effect of film and temperature on the sensory, microbiological and nutritional quality of minimally processed cauliflower

The effect of atmosphere modification, generated using three different packaging films, on the quality of cauliflower minimally processed when stored at 4 or 8 °C for up 20 days was evaluated. The colour, texture, weight loss, sensory attributes, as well as microbial counts and sugars and ascorbic acid content were determined. The atmosphere generated with the perforated polyvinylchloride (PVC) film was hardly modified, whereas the other two films (non-perforated PVC and polypropylene films) originated changes in CO₂ and O₂ levels during storage. The different packaging conditions and storage temperature influenced yellowing. An increase in shear force was observed. Weight losses were below 5%. Mesophiles and Pseudomonas counts were below 7 log CFU g⁻¹, the populations being lower with film B and film C than with film A. Cauliflower maintained an acceptable appearance in all the films studied. Total sugars decreased about 27% after 20 days of storage, whereas ascorbic acid did not change.     

The sensory and microbiological quality of fresh sliced mushroom (Agaricus bisporus L.) packaged in modified atmospheres

The effect of modified atmospheres, generated by using different packaging films, on the quality of sliced mushrooms was evaluated. The carbon dioxide and oxygen content inside the packages as well as the colour, texture, weight loss, sensory attributes, mesophiles, psychrotrophs, Pseudomonas fluorescens, faecal coliforms, Escherichia coli and anaerobic spores were determined. Modified atmospheres containing 2.5% CO₂ and 10–20% O₂ reduced the microbial counts and improved the mushrooms’ appearance when compared with an air atmosphere. Modified atmospheres containing 15% CO₂ and <0.1% O₂ inhibited mushroom development and toughening and reduced microbial growth. Although these atmospheres had no effect on colour, they did allow the development of off odours and anaerobic spores were detected. No differences in microbial growth or mushroom spoilage were observed under the different moisture contents generated in the packages at 4 °C. Aerobic bacteria counts were considered very high even at the beginning.     

Effects of packaging type, gas atmosphere and storage temperature on survival and growth of Listeria spp. in shredded dry coleslaw and its components

The survival and growth of Listeria populations inoculated on to dry coleslaw mix and its components were investigated, focusing on effects of storage temperatures and gas atmospheres within packaging films or storage chambers. There were few significant effects of packaging film at 3 °C, but at 8 °C the elevated CO₂/low O₂ atmospheres generated within orientated polypropylene (OPP) packages and used in controlled atmosphere chambers were inhibitory. Although two strains of Listeria monocytogenes had survival characteristics comparable with Listeria innocua, L. monocytogenes ATCC 19114 survived better at 3 °C and also in the elevated CO₂/low O₂ atmospheres within OPP at 8 °C. The effects of product components on the survival of L. innocua were linked to storage temperature. Shredded carrot reduced initial counts and at 8 °C inhibited survival of L. innocua in comparison with shredded cabbage.     

Sensory, Colour and Psychrotrophic Bacterial Analyses of Squids (Loligo plei) During Storage in Ice

The after catch quality decrease of squid, Loligo plei, was evaluated, comparing two storage treatments: contact and non-contact with ice. The squids were evaluated for their sensory, instrumental colour and psychrotrophic bacterial count changes. A principal component analysis of the sensory data indicated that the squid quality markedly decreased after 7 days of storage, in both treatments. The instrumental colour analysis showed that the red and yellow colours of the squid skin increased with time in both treatments, while in the muscle, the intensity of the red and yellow colours increased more in the non-contact than in the contact with ice treatment. The results of the sensory and instrumental colour analyses were highly correlated, both being adequate for squid quality evaluation. The storage methods did not affect the development of bacterial counts, which in both treatments were below 106 cfu/g of muscle after 16 days of storage. The results showed that in both treatments the end of the shelf-life of L. plei squid was determined by the loss of its sensory quality. The packaging of the squids resulted in more intense changes in the characteristic colour of the squid muscle, and did not promote a significant reduction in microbial growth. Thus the non-contact ice storage method presented no advantages when compared with the contact ice storage method with respect to the quality preservation of L. plei under laboratory conditions.     

Effect of varying the gas headspace to meat ratio on the quality and shelf-life of beef steaks packaged in high oxygen modified atmosphere packs

Beef steaks (M. longissimus dorsi) were stored in modified atmosphere packs (MAP) (80% O₂:20% CO₂) with gas headspace to meat ratios of 2:1, 1:1 and 0.5:1 for 14 days at 4 °C. The pH, surface colour, texture and microbiology of beef steaks were unaffected (P > 0.05) by varying the gas headspace to meat ratio. APLSR (ANOVA-partial least squares regression) and jack-knife uncertainty testing indicated that lipid oxidation (TBARS) was significantly positively correlated with days 10 (P < 0.05) and 14 (P < 0.001) of storage. Chemical and sensory detection of lipid oxidation in beef steaks were in agreement on day 14 of storage. The sensory quality and acceptability of beef steaks were similar in gas headspace to meat ratios of 2:1 or 1:1 and unacceptable in 0.5:1. Results indicate that pack size and gas volume can be reduced without negatively affecting fresh beef quality and shelf-life.     

The effects of washing treatment on antioxidant retention in ready-to-use iceberg lettuce

The influence of washing treatment on the retention of key antioxidants in minimally processed iceberg lettuce was examined. Shredded iceberg lettuce was subjected to one of three washing treatments: a domestic wash (tap-rinsed), immersion in distilled water (water-dipped) or immersion in chlorinated water (chlorine-dipped). Lettuce was subsequently packed in oriented polypropylene bags and flushed with 100% nitrogen and stored at 4 °C. Vitamin C (ascorbic acid and dehydroascorbic acid), total phenols, total antioxidants, individual phenols, individual carotenoids, colour measurements and pH were quantified on production day and throughout the storage period (8 days). Different groups of antioxidants were found to differ in their response to washing treatments. No significant ( P  > 0.05) effects of washing treatment were observed on total antioxidant activity, total phenolics and on the levels of individual phenolics (chicoric acid, chlorogenic acid and caffeic acid). Individual carotenoids were initially affected by washing treatment, with higher levels of lutein and beta-carotene retained with domestic washed lettuce. Ascorbic acid was the antioxidant most affected by washing treatments with domestic washing resulting in significantly ( P  ≤ 0.05) higher retention of ascorbic acid throughout the storage period compared with the chlorine-dipped lettuce.     

青砖茶的加工工艺、品质及生理作用研究进展

青砖茶属于黑茶类,产自于我国鄂南地区,是边疆少数民族不可或缺的生活饮品。通常以老青茶为原料,经毛茶初制、增湿渥堆、复制拼配、蒸压成型和烘房干燥这五道工序加工制成。其中最关键的步骤为增湿渥堆,这一过程中茶叶内含成分的转化情况直接影响青砖茶的品质。对其品质的分析,一般先从色泽、滋味、香气等方面进行感官审评,再通过检测茶叶中的茶多酚、咖啡碱、可溶性糖以及香气活性成分等物质含量来综合评定。优质的青砖茶外形平整、茶汤色泽透亮、滋味醇厚、陈香悠长,因此深受人们喜爱。此外,青砖茶还具有抗氧化、抗肥胖、降血脂以及调节肠道菌群等多种生理功效,极具开发价值。本文综述了青砖茶的加工工艺、品质特性和生理功效的研究进展,以期为青砖茶品质的提升及其保健功效的深入研究提供理论依据。     

Low dose gamma irradiation of raw meat. I. Bacteriological and sensory quality effects in artificially contaminated samples

Filet américain, consisting of raw, ground meat (beef) mixed with mayonnaise sauce, and the corresponding raw beef (without sauce) were experimentally contaminated with different strains of Salmonella. Yersinia enterocolitica and Campylobacter jejuni and irradiated with doses up to 1.5 kGy.Radiation resistance (D value) was determined immediately after irradiation. For the evaluation of the irradiaion effect on Y. enterocolitica in relation to storage, a number of samples were stored for a few days at 3°C and the microbiologically examined.D values of S. typhimurium, S. anatum, S. panama and S. stanley (strains isolated from retail filet américain) irradiated in filet américain were found to be 0.37, 0.45, 0.41 and 0.61 kGy and in raw beef 0.55, 0.67, 0.66 and 0.78 kGy, respectively. D values of Y. enterocolitica serotypes 0:3, 0:5, 27 and 0:9 irradiated in filet américain were 0.043, 0.065, and 0.080 kGy and in raw beef, 0.10, 0.16 and 0.21 kGy, respectively. D values of C. jejuni (three strains) irradiated in filet américain were 0.11, 0.08 and 0.09 and in beef 0.15, 0.14 and 0.16 kGy, respectively.It is concluded that doses as low as 1 kGy are effective in reducing Salmonella by approximately 1.6–2.7 log cycles in filet américan and 1.3–1.8 log cycles in ground meat. Numbers of Y. enterocolitica and C. jejuni are always reduced by more than 4 log cycles with this dose.On sensory evaluation 38% of samples of filet américain irradiated directly with 1 kGy were not acceptable for a taste panel; preference was for the unirradiated sample in 82% of the cases. However, when beef was irradiated with the same dose prior to the addition of mayonnaise sauce no significant taste differences could be observed between nonirradiated and irradiated samples.     

卷烟原料的感官质量与化学成分的关系研究

目的 探究卷烟原料的感官质量与化学成分的关系。方法 对2016年的99个卷烟原料进行感官质量评价和化学成分检测, 采用简单相关分析方法和典型相关分析方法进行分析。结果 醇化前后片烟的感官质量与化学成分相关性基本一致, 具体表现为还原糖、还原糖与总糖之比、还原糖/总植物碱之比、总钾与感官质量显著(P<0.01)正相关, 总氮、氮碱比、总植物碱、总氯与感官质量显著(P<0.01)负相关, 关联大小按其先后顺序依次递减。结论 本研究表明了卷烟原料化学成分与感官质量存在一定相关性, 可为今后采用化学成分来判断卷烟原料最佳醇化期提供理论支撑依据。     

The effect of pectin concentration on viscoelastic and sensory properties of processed cheese

The effect of pectin addition on viscoelastic properties of model processed cheeses with 40% w/w dry matter and 50% w/w fat in dry matter after 42 days of storage at temperature 6 ± 2 °C has been investigated using dynamic oscillation rheometry (plate–plate geometry; frequency range 0.1–50.0 Hz; temperature 20 °C). The role of pectin concentration (0.2%, 0.4%, 0.6% and 0.8% w/w) has been studied. Also, the sensory evaluation of samples has been made to assess cheese appearance, rigidity, spreadability and flavour. All samples with the pectin addition were more rigid and less spreadable compared with processed cheeses without pectin. With the increasing concentration of pectin the storage ( G ') and loss ( G ") moduli rose at the whole tested frequency range (0.1–50.0 Hz). Growing pectin content resulted in the decrease in loss tangent (the nature of gel was changed to more elastic material). The dependence of processed cheese rigidity on pectin concentration (in range 0–0.8% w/w) was not linear. The appearance and flavour were not worse by pectin addition.