SHELF-LIFE AND QUALITY OF‘NAVAHO’ AND ‘SHAWNEE’ BLACKBERRY FRUIT STORED UNDER RETAIL STORAGE CONDITIONS1

The quality of soft-fruited (‘Shawnee’) and firm-fruited (‘Navaho’) blackberry cultivars held under simulated retail conditions was determined. Leakage and decay increased during storage and exceeded 20% in 'Shawnee’ fruit after 14 days at 2C or 7 days at 5C, while ‘Navaho’ held under similar conditions was still marketable (<10% decay). Transferring fruit to 20C for 2 days after low temperature storage intervals was detrimental to fruit quality, resulting in increased weight loss, leakage, decay and softening in both cultivars. After retail warming, ‘Shawnee’ fruit lost 25% of marketable fruit while‘Navaho’ had a 10% loss. Soluble solids concentration did not change significantly during storage, but titratable acidity declined 40–50%. Anthocyanin content increased from 20–100% depending on cultivar, storage temperature and storage intervals. The sugar composition of blackberries before storage was about 10, 260 and 260 mg/g dry weight, glucose, and fructose, respectively. Sucrose and glucose decreased and fructose increased slightly during storage. Warming fruit after low temperature storage did not accelerate loss of total sugars. If held constantly at 2C, ‘Navaho’ could be held 21 days.     

POSTHARVEST CHANGES IN FRESH SWISS CHARD (Beta vulgaris, type cycla) UNDER DIFFERENT STORAGE CONDITIONS

The effects of storage temperature and relative humidity on the quality of Swiss chard (Beta vulgaris, type cycla) were investigated. Quality was assessed through determinations of water content, weight loss, chlorophyll content, pH, titratable acidity, soluble solids content and sensory evaluations. Storage conditions were 4 and 18C and 43, 86 and 98% relative humidities (RH). The quality of chard leaves was unacceptable after three days of storage at 18C, independent of the RH. Chard leaves kept at 4C and 86 and 98% RH remained acceptable for 9 days. The dehydration suffered by samples kept at 4C and 43% RH turned them unacceptable after 4 days of storage.     

CHANGES IN TOTAL PHENOLIC AND FLAVONOID CONTENTS OF ROWANBERRY FRUIT DURING POSTHARVEST STORAGE

ABSTRACT

Postharvest storage conditions of rowanberry (Sorbus aucuparia) fruits were investigated. The influences of temperature and storage time on total phenolic content were observed. Both variables affected phenolic content of rowanberries, and their total phenolic contents significantly reduced during the 20‐day storage at 4 and 22C. The loss of total phenolic was found to be almost 50% of its initial amount (3,619.8 mg/kg fresh weight [fw]) at 22C, which was higher than occurred loss (30%) at 4C. An investigation of rowanberry flavonoids showed the presence of rutin, quercetin‐3‐glucoside and quercetin‐3‐D‐galactoside (Q3DG). Quantitative analysis of berry flavonoids showed Q3DG as a major compound, being 24.55 mg/kg fw. The highest reduction (86% of its initial amount) was also seen in that compound level compared with other ones. Degradation kinetics of flavonoids was studied at 22C over 16 days of storage. Checking of model adequacies indicated that their reductions followed a first‐order kinetic.

PRACTICAL APPLICATIONS

Postharvest storage has been taken, increasing the interest of scientists because of various reasons, one of which is explained next. The presented results indicated the direct and/or indirect influence of storage conditions on the quality of berries, implying that whoever is planning to store plant and/or plant origin food products in a refrigerator or at room temperature should consider the conditions and their possible effects on the quality parameters from the aspects of economics and nutritional properties of products. In the present study, the stability of an important bioactive group, phenolics, in rowanberries and the influences of environmental conditions were examined, and additionally, degradation kinetics of major phenolic group, flavonoids, was analyzed. The results are valuable and helpful for the evaluation of the postharvest storage and its effect on rowanberries. Introduced model may be helpful for the prediction of storage time required for the degradation of phenolics up to the acceptable limit.     

MICROBIOLOGICAL QUALITY OF WHEAT STORED UNDER DIFFERENT CONDITIONS IN TURKEY

Four different types of wheat storage systems are widely used in the Marmara region. The existing storage conditions were studied and changes in the microbiological quality of the stored wheat under these conditions were assessed.
Depending on the external conditions, ambient temperatures and relative humidities in the stores were 17–26°C and 50–65% RH during summer and 3–10°C and 62–83% RH during winter, respectively. The low relative humidity level during harvesting and subsequent storage was adequate for obtaining low levels of moisture content and water activity in the produci for safe storage. The increase in relative humidity of the air during winter months did not affect the moisture content of the product considerably and the low temperature prevented mold growth. Therefore, all of the four different storage facilities were suitable for safe storage of grain for a period of one year without significant losses in quality due to microbiological load.     

CHANGES IN PROTEIN COMPOSITION DURING STRAWBERRY (Fragaria × ananassa Duch.) FRUIT RIPENING1

The changes in strawberry native proteins and polypeptides during ripening were studied. Analysis of protein extracts by nondenaturing electrophoresis showed the presence of a protein species only in the ‘25% Red’ and later ripening stage. This 40 kD polypeptide was hardly detected in ‘Large green’ and ‘White’ fruit extracts. The polypeptide profile, obtained with SDS-PAGE, also changed during ripening. While most polypeptides were found in all ripening stages, the distribution of some of them varied during ripening. Protein synthesis (measured by ³⁵ S-methionine labelling) in strawberry was mainly directed towards the regeneration of previously existing proteins. As ripening proceeded, the synthesis of 67 and 63 kD polypeptides increased, while those of 82, 56 and 25 kD decreased. Three very-abundant polypeptides (36, 24 and 23 kD) were located in the achenes and were not labelled in any ripening stage.     

FACTORS INFLUENCING THE BREAKDOWN OF FRUIT IN STRAWBERRY JAM

Abstract. Structural changes produced in strawberries when made into jam were studied by light microscopy. The results indicated that only the epidermal and vascular tissues retained their structural integrity, whereas the bulk of the cells were collapsed and in some instances ruptured. The extent to which fruit of different cultivars broke down during the jam making process was determined, and an expression representing fruit wholeness was derived. It is concluded that a relationship exists between the extent to which strawberries disintegrate during jam boiling and the density of achenes on the surface of berries of a given size.     

QUALITY DECAY OF FRESH PROCESSED FISH STORED UNDER REFRIGERATED CONDITIONS

The ability of commercial fresh fish to be processed to produce fresh-fish based hamburger was assessed in this work. In particular, four commercially important fish species, i.e., hake ( Merluccius merluccius ), mackerel ( Scomber scombrus ), sea bass ( Dicentrarchus labrax ) and sea bream ( Sparus aurata ) were packed in an aluminium/plastic laminated film, stored at 4C, and studied for changes in trimethylamine (TMA) and biogenic amines such as histamine, cadaverine, putrescine and spermidine. In terms of TMA content, results suggest that sea bass and sea bream resulted into species suitable to be fresh processed having a TMA acceptability limit of 5.5 and 10 days, respectively, whereas in the same conditions, hake and mackerel resulted highly perishable products with a TMA acceptability limit of 2.2 and 1.7 days, respectively. Concerning food safety related to histamine content, for the entire period of observation all species showed an amount lower than the maximum content allowed (100 ppm).

PRACTICAL APPLICATIONS

This work is an interesting investigation on the possibility to process fresh fish. The results of the research can be advantageously used by fish industry. The fish-based hamburger represents a strategic solution to overcome the barrier to fish consumption that is subjected to many influences among which one is the consideration of fish as time-consuming meal.     

POSTHARVEST CHANGES OF PECTIC SUBSTANCES IN CHILLED PEACHES

ABSTRACT Red Globe peaches were harvested at the threshold-mature stage and either stored at OC after preripening at 20C for 48 h or stored directly at 2C. Total pectin increased from 7.49 mg/g fresh weight in the threshold-mature sample to 10.21 mg/g in pre-ripened fruit stored at OC and 12.83 mg/g in fruits stored directly at 2C. Depending on extraction and storage protocol, between 26% and 73% of total pectin was solubilized. Chelator-soluble fractions had a low degree of esterification (DE ca. 20%), whereas other fractions were highly methylated (DE ca. 56% to 74%). Average DE did not vary between samples. DEAE-cellulose chromatography revealed an uneven distribution of methoxyl groups. Two prominent peaks were observed in chromatograms of chelator-soluble extracts from threshold-mature fruit and fruit stored directly at 2C. One peak was observed in chelator-soluble pectin from preripened fruit stored at OC.     

POSTHARVEST CHANGES DURING STORAGE OF PACKAGED RADICCHIO1

Radicchio (Cichorium intybus L., var. foliosum) heads were held at two temperatures in plastic dome lid boxes, 10 μm polyethylene produce bags, or 12. 7 μm EHC Clysar plastic shrink-wrap bags to determine postharvest quality changes. Respiration rate of < 10mL CO₂ kg^-1 h^-1 at 1C indicates that radicchio is a moderately respiring commodity. Radicchio held in plastic dome lid boxes lost > 7% fresh weight while those in polyethylene or EHC bags lost < 1% fresh weight during 1 week of storage at either 10C or 1C. Color changes in radicchio occurred primarily in the red portion of the leaf area. Heads faded and lost color saturation between 1 and 4 weeks of storage at 1C. These changes were concomitant with the browning of the leaves. At 10C, heads held in produce or EHC.     

POSTHARVEST DIPS TO CONTROL BLACK SPECK AND SCAR DISCOLORATION IN STORED BROCCOLI

The overall objective of this study was to evaluate the effects of postharvest dips on black speck development and scar discoloration in broccoli. Postharvest chlorine dips of 100, 200 or 300ppm for 5 or 10 min consistently reduced black speck development and scar discoloration in broccoli stored 4 weeks in air at 1C. Concentrations of 200 and 300ppm chlorine were also effective at reducing black speck and scar discoloration, respectively, in broccoli stored 4 weeks in controlled atmosphere (CA, 1% O₂ and 12% CO₂) at 1C. Citric (1%) and ascorbic (1%) acids, on the other hand, increased both black speck and scar discoloration, while L‐cysteine (0.01%) and combinations of citric (1 or 2%) and ascorbic (1 %) acids had no effect.     

EFFECT OF OXYGEN CONCENTRATION ON THE BIOCHEMICAL AND CHEMICAL CHANGES OF STORED LONGAN FRUIT

ABSTRACT

Longan fruits were stored for 6 days in atmosphere of 5, 21 (air) or 60% O₂ (balance N₂) at 28C and 90–95% relative humidity to examine effects of low and high O₂ concentration on enzymatic browning and quality attributes of the fruit. Changes in pericarp browning, pulp breakdown, disease development, total phenol content, activities of phenol metabolism‐associated enzymes, relative leakage rate, α,α‐diphenyl‐β‐picrylhydrazy (DPPH) radical scavenging activity, and contents of total soluble solids, titratable acidity and ascorbic acid were evaluated. Storage of fruit in a 5% O₂ atmosphere markedly delayed pericarp browning in association with maintenance of high total phenolic content and reduced activities of polyphenol oxidase (PPO), peroxidase (POD) and phenylalanine ammonia lyase. Moreover, the fruit stored in a 5% O₂ atmosphere exhibited a lower relative leakage rate and higher DPPH radical scavenging activity than fruit stored in air. This presumably was beneficial in maintaining compartmentation of enzymes and substrates, and thus, reducing pericarp browning. Pulp breakdown and disease development were also reduced by exposure to a 5% oxygenatmosphere. On the contrary, exposure of longan fruit to a 60% O₂ atmosphere accelerated pericarp browning, pulp breakdown and decay development. PPO and POD activities and relative leakage rate were similar for control and 60% O₂‐treated fruit after 4 and 6 days of storage. Furthermore, treatment with 60% O₂ significantly decreased the phenolic content and DPPH scavenging activity of fruit. In addition, exposure to 5 or 60% O₂ resulted in a higher level of total soluble solids, but a lower level of ascorbic acid of longan fruit flesh. In conclusion, exposure to a 5% O₂ atmosphere showed great potential to reduce pericarp browning and extend shelf life of longan fruit.

PRACTICAL APPLICATIONS

Pericarp browning and pulp breakdown are the major causes of deterioration in postharvest longan. Conventional controlled atmosphere with low O₂ and high CO₂ is effective in maintaining quality and extending shelf life of fruits and vegetables, including inhibition of tissue browning. In this study, 5%‐controlled atmosphere reduced significantly pericarp browning, pulp breakdown and rot development. It could potentially be useful as a postharvest technology of longan fruit for reducing or replacing the use of chemicals such as SO₂ and fungicides, but it requires further investigation.     

SHELF-LIFE OF VACUUM-PACKAGED EVISCERATED BROILER CARCASSES UNDER SIMULATED MARKET STORAGE CONDITIONS

The effects of vacuum-packaging on the shelf-life of eviscerated broiler carcasses, under conditions simulating market storage (4, 7 and 9C) in the State of Kuwait were studied. Vacuum-packaging increased the shelf-life of the carcasses by 7–8, 6 and 4 days beyond that of the conventionally-packaged carcasses, when stored at 4, 7 and 9C, respectively. The growth of the Enterobacteriaceae was lowest in carcasses stored at 4C, irrespective of the packaging type. Of the Enterobacteriaceae, the coliforms were the predominant microorganisms (∼ 80%), whereas Salmonella accounted for up to 15% . Lactobacillus were the predominant spoilage microorganisms in the vacuum-packaged carcasses, whereas Pseudomonas predominated in the conventionally-packaged ones. Vacuum-packaging can be recommended for improvement of the keeping quality of eviscerated broiler carcasses, but it should also be associated with strict procedures for controlling the handling and storage temperatures throughout the overall distribution system .