Early Days Of Storage Research Articles

Red cabbage extract immobilized in bacterial cellulose film as an eco-friendly sensor to monitor microbial contamination and gamma irradiation of stored cucumbers

The aim of the present study is to develop a pH-sensing biopolymer film based on the immobilization of red cabbage extract (RCE) within bacterial cellulose (BC) to detect contamination and gamma radiation exposure in cucumbers. The results obtained show a sensitivity to pH changes for RCE in its aqueous form and that incorporated within BC films (RCE-BC), both showed color change correlated to bacterial growth (R2 = 0.91), this was supported with increase in pH values from 2 to 12 (R2 = 0.98). RCE and RCE-BC exposure to gamma radiation (0, 2.5, 5, 10, 15, 20, 25 kGy) resulted in gradual decrease in color that was more evident in RCE aqueous samples. To sense bacterial contamination of cucumbers, the total count was followed at 0, 5, 10 and 15 days in cold storage conditions and was found to reach 9.13 and 5.47 log cfu/mL for non-irradiated and 2 kGy irradiated samples, respectively. The main isolates detected throughout this storage period were identified as Pseudomonas fluorescens, Erwinia sp. Pantoea agglomerans using matrix assisted laser desorption ionization–time of flight-ms (MALDI–TOF–MS). Bacterial growth in stored irradiated cucumbers was detected by color change within 5 and 10 days of storage, after which there was no evident change. This is very useful since contamination within the early days of storage cannot be sensed with the naked eye. This study is the first to highlight utilizing RCE and RCE-BC as eco-friendly pH-sensing indicator films for intelligent food packaging to detect both food contamination and gamma preservation for refrigerator stored cucumbers.

Combined effect of plasma treatment and equilibrium modified atmosphere packaging on safety and quality of cherry tomatoes

Combination of novel technologies for post-harvest processing can have advantages in terms of food safety and quality to reduce food waste. In this work the combination of cold plasma treatment and an equilibrium modified atmosphere packaging (EMAP) for cherry tomatoes was investigated under controlled temperature (10 and 20 °C) throughout storage. Results show that applying a plasma treatment to cherry tomatoes preserved the sensorial quality characteristics of the treated product. A reduction of microbial load on the product surface due to the plasma treatment was demonstrated. Package was important to prevent weight loss and changes in total soluble solid content over 14 days of storage. A higher microbiological growth was detected within the packed cherry tomatoes, while a plasma treatment before packing reduced microbiological growth during the early days of storage. The combination of a cold plasma treatment, storage temperature and EMAP design ensured the quality retention of cherry tomatoes, which suggests that they have potential to be used as hurdle technology. The right combination of different preservation technologies is able to reduce food waste and prolong the shelf life and quality of highly perishable vegetable goods.

Effects of Chitosan Coating with Putrescine on Bioactive Compounds and Quality of Strawberry cv. San Andreas During Cold Storage

The effect of postharvest treatment of Putrescine (PUT) alone or in combination with chitosan on maintaining quality of strawberry cv. San Andreas during cold storage was investigated. The treated strawberry fruits were examined for weight loss, soluble solids content, titratable acidity, ascorbic acid contents, total anthocyanins, total phenolic contents, antioxidant content, decay incidence and sensory analysis throughout the 15 storage days at 1 °C and 90–95% relative humidity. Fruit coated with chitosan and chitosan + PUT coatings showed significant delays in the change of weight loss and decay percentage as compared to uncoated fruit. Although alone PUT application was effective in the early days of storage, it was not as effective as coating treatments towards the end of storage. The addition of Putrescine into the chitosan coating solution had a positive effect on maintaining higher concentrations of total anthocyanins, total phenolic and antioxidant content, which decreased in control fruit due to over-ripening and senescence processes. Likewise, sensory analysis results also showed the effectiveness of chitosan + PUT treatment by retaining the quality of strawberry. These findings suggest that the chitosan + PUT coatings are useful for extending the shelf-life and maintaining quality of strawberry fruit at 1 °C.

Comparison of the influence of defined storing conditions on asian and european pear cultivars

The study observed changes in the material composition of European (Conference) and Asian (Yali) pears during the storage period at different temperatures. Three different temperatures were selected for storing, i.e. 1 °C, 5 °C and 20 °C. Assessed for each of the pieces of fruit were flesh firmness, titratable acidity, soluble solids content, content of organic acids, and production of ethylene and carbon dioxide. Fruit stored at 1 °C and 5 °C was analysed before the moment of putting to the store and then after 25, 55 and 70 days of storing. Fruit stored at 20 °C was analysed before the moment of putting to the store and then after 14, 22 and 30 days of storing. The respiration intensity observed through carbon dioxide production at refrigeration conditions was approximately of the same progress for both of the varieties. For the Yali variety, the intensity of respiration of the fruit at the start of the storing period strongly decreased.The same progress was recorded for the Conference variety. Storing at 20 °C increased the respiration intensity. The varieties Yali and Conference which were stored under the temperature of 5 °C had the highest CO2 production after 70 days of storage. For both varieties the lowest ethylene production during storage was observed at 1 °C. Ethylene production was higher in Yali pear fruits. The Yali variety stored at 20 °C from the beginning produced up to 10 times higher concentration of ethylene than the fruit of the Conference variety. The highest amount of ethylen by the Conference variety was produced by the fruits which were stored under the temperature of 5 °C. At the beginning of the storage period the Conference pears had two-fold higher flesh firmness than the Yali fruit. Fruits of the varieties Yali and Conference which were stored 70 days under the temperature of 1 °C had the highest flesh firmness. For soluble solids and titratable acidity no clear progress was recorded. Malic acid was predominant in both varieties. The Yali fruit contained more citric acid than the Conference fruit. In both varieties soluble solids gradually increased in the early days of storage at all of the monitored temperatures.

Influence of chitosan coatings with citric essential oil on the shelf-life of minimally processed mango (<i>Mangifera indica</i> L.)

Demand for minimally processed fruits have increased due to their nutritional value and an increasing change in consumption habits. Physicochemical, microbiological, structural and sensory changes were determined in minimally processed mangoes (MPM) with chitosan (CH) edible coatings and lemon and orange essential oils (EOL). The MPM was first dipped in citric acid and a texturizing solution and then dipped in CH and lemon or orange EOL coatings. Weight loss, sensory acceptance, total soluble solids, total acidity, ascorbic acid, color changes, firmness and elasticity, and microbiological changes were quantified for 11 days of refrigerated storage. The CH and lemon EOL coating had more acceptance than the other treatments. No differences were found (p>0.05) for weight loss, total acidity, ascorbic acid, firmness or elasticity. There was a high amount of total phenols due to the EOL composition, as well as a high antioxidant capacity in the early days of storage. This characteristic decreased in the final days of the study. There was a decrease in the microbial charge for the lemon EOL treatment, as compared to the other samples. The CH and lemon EOL coating helped to maintain the shelf-life of the MPM for 11 days of storage without affecting the sensory acceptance. The CH and Orange EOL coating did not have an effect on the MPM physicochemical attributes; however, the sensory acceptance was negatively affected with off-flavors conferred to the MPM.

POLYGALACTURONASE AND PECTIN METHYLESTERASE ACTIVITIES OF CaCl<sub>2</sub> TREATED RED-FLESHED DRAGON FRUIT (<i>HYLOCEREUS POLYRHIZUS</i>) HARVESTED AT DIFFERENT MATURITY

Fruits harvested at different maturity possess different biochemical constituents and physiological properties that make the fruits may react somewhat differently to the postharvest treatment. A study to examine the activity of Polygalacturonase (PG) and Pectin Methylesterase (PME) enzymes during storage in dragon fruit (Hylocereus polyrhizus) harvested at 28 days (Index 3) and 34 days (Index 5) after anthesis and postharvest treated with 0, 2.5, 5.0 and 7.5 g L-1 CaCl2 was performed. The PG activity was lower in younger fruit and vice-versa for PME activity. Increasing concentration of CaCl2 effectively reduced the activity of both enzymes. PG activity for fruit treated with 0, 5 and 7.5 g L-1 CaCl2 increased linearly with the time of storage while its activity for the fruit treated with 2.5 g L-1 CaCl2 was lower at the beginning of storage. PG activity of Index 5 fruits increased almost linearly during storage while its activity in Index 3 fruits was low at the early days of storage and later continued to increase until day seven. At both maturity indices, the PME activity was low at the early days of storage and later continued to increase until day seven. Overall, results obtained indicated that CaCl2 postharvest treatment reduced both PME and PG activities thus slowing down the softening process giving an evident that calcium possess a distinguishable role in the reducing softening of fruit, regardless of maturity index.

Changes in main nutrients and medicinal composition of Chinese yam (Dioscorea opposita) tubers during storage.

The changes in the main nutrient and medicinal components during the storage of the Chinese yam (Dioscorea opposita) tubers were studied. The harvested tubers were stored under ambient conditions (10°C to 18°C, 60% to 80% Relative Humidity) and cold temperature and packaged conditions (4°C, 60% to 65% Relative Humidity) for 45day. The allantoin, starch, total alcohol-soluble sugar, reducing sugar, protein, and moisture contents of the samples were evaluated. Their amylase activities were also investigated. Results of ambient conditions indicated that, during storage, moisture decreased by 67.96% to 56.51%, and total sugars, reducing sugars, and protein increased by 6.49% to 9.81%, 1.7% to 2.27%, and 13.02% to 14.55%, respectively. Starch and enzyme activities increased during the early days of storage and progressively decreased, and the content of allantoin changed in volatility. The changes were more significant at cold temperatures and packaged conditions than at ambient conditions. This result suggests that after-ripening occurred in the early stages of Chinese yam tubers, which positively affected the nutritional potential of the tubers by a marked increase in nutrients. Low-temperature sweetening greatly affects the nutritional potential of tubers by a series of complicated interactions between starch and sugars at 4°C.

Effect of Ganghwayakssuk (Artemisia princeps Pamp.) on oxidative stability of deep fried chicken nuggets

This study was conducted to examine the antioxidant effects of various levels of added ganghwayakssuk (Artemisia princeps Pamp.) extract on deep fried chicken nuggets. The frying loss, pH, and yellowness values of all treatments were higher than those of the control (p<0.05). Additionally, the lightness and redness values of all treatments were lower than those of the control and as the amount of ganghwayakssuk ethanolic extracts (GEE) increased. At the end of the storage period (day 10), the peroxide values (POV), conjugated dienes (CD), and thiobarbituric acid reactive substances (TBARS) values were lower than those of the control. The sensory evaluation of all samples was not different significantly at the early days of storage (p<0.05). With increases in the storage period, deep fried chicken nuggets containing various levels of GEE had higher overall acceptability than those of the control. The results demonstrate that ganghwayakssuk has strong lipid antioxidation activity added to deep fried chicken nuggets.

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 cm 3 O 2 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 O 2 and CO 2 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.

Extractive component changes in the foot muscle of live small abalone during storage

Changes in the freshness indices and extractive components in the foot muscle of live small abalone Haliotis diversicolor during storage at 5∞C, 15∞C, and 25∞C were investigated. The pH values declined with storage time. Volatile basic nitrogen and the K-value increased gradually with storage time at 15∞C and 25∞C, but changes were small at 5∞C. The onset of initial decompo- sition of samples was observed after 3.5 days at 5∞C, after 2.5 days at 15∞C, and after one day at 25∞C. Adenosine triphosphate and adenosine diphosphate degraded rapidly within the early days of storage. In contrast, levels of adenosine monophosphate increased and exhibited prolonged accu- mulation throughout the storage period. The total amount of free amino acids increased markedly during storage. The dominant free amino acids, such as taurine, glutamic acid, glycine, alanine, and arginine, also increased after storage.

Keeping quality of milk in relation to the copper content and temperature of pasteurization

SUMMARYFor milk from four herds of cows, maintained under different conditions of feeding and management, the natural Cu content and the stability of the ascorbate were highly correlated. Low Cu levels in milk from cows at pasture at farms A and B during the summer were associated with low storage losses of ascorbate. During this period, the milk of cows at farms C and D (on forage and Cu-supplemented concentrate) was richer in Cu, and losses of ascorbate were high. Heat treatment of the milk stabilized the ascorbate. Thus, in ‘high Cu’ milk (60 µg Cu/l), loss of ascorbate in the raw milk was 58% at 2 d, as against 17% after pasteurization at 72 °C and no loss after treatment at 82 °C. Storage of milk in light caused rapid destruction of ascorbate, equally with 72 and 82 °C heat treatments. The effects were examined of milk pasteurization temperature (72–82 °C) on flavour stability, bacteriological quality and vitamins of the B-complex. Heat treatment at 82 °C increased the susceptibility of vitamin B12to destruction by light, but otherwise caused no greater losses of B-complex vitamins than did treatment at 72 °C. Taste panel ratings showed an initial preference for milk heated at 72 °C, but on storage of this milk in darkness the flavour score fell progressively and at 5 d it was judged ‘stale’. Treatment at 82 °C gave a faint ‘cooked’ flavour although, unlike that of the 72 °C-treated milk, the flavour remained stable throughout 14-d storage and after d 8 was increasingly preferred. On exposure to light after treatment at 72 °C milks rapidly acquired an unpleasant‘oxidized’ flavour, but after treatment at 82 °C, exposure to light had no such adverse effect on flavour during the early days of storage. Pasteurization at ∼ 80 °C offers a potential for improvement in the oxidative stability of milk and its contribution of vitamin C to the diet.