RESPONSE OF 1-METHYLCYCLOPROPENE TREATED "GRANNY SMITH" APPLE FRUIT TO AIR AND CONTROLLED ATMOSPHERE STORAGE CONDITIONS

ABSTRACT

In the study, the efficacy of 1‐Methylcyclopropene (1‐MCP) on the quality of apples cv. “Granny Smith” was examined. Fruits were stored for 120 and 180 days at 0 ± 0.5C and 90 ± 5% relative humidity (RH) under normal (NA) and controlled atmosphere (CA), and samples taken at 120 and 180 days of storage were kept at 20 ± 2C and 60 ± 5% RH for 7 days. Weight loss was higher in fruits stored under NA. The lowest respiration rates were in CA while the highest rates were found in NA‐stored fruits without pretreated. 1‐MCP + CA reduced the internal ethylene concentration from 10.63 µL/L to 0.60 µL. The incidence and severity of superficial scald was 68.10 and 77.00% in fruits stored in NA. 1‐MCP consistently suppressed the expression of superficial scald. 1‐MCP maintained the quality fruit kept in CA and NA environments to a higher degree than nontreated apples over a 180‐day storage period. The results indicated that cv. “Granny Smith” could be stored successfully under 1‐MCP + CA conditions and that 1‐MCP + NA may be a viable alternative to CA for optimal eating quality.

PRACTICAL APPLICATIONS

1‐Methylcyclopropene (1‐MCP) is an effective inhibitor of ethylene action and it binds irreversibly to ethylene receptors. 1‐MCP delays the onset of the climacteric ripening of fruits. Recently research has been conducted on the effects of 1‐MCP on postharvest behavior of fruits and vegetables with the objective of reducing physiological disorders and quality losses to prolong their commercial life. The use of 1‐MCP is easy. It is important that the fruit treated with 1‐MCP reach a good sensory quality at the commercial level. Superficial scald of apples is a physiological disorder, which following long‐term storage has the potential to destroy the market value and utility of millions of tons of fresh apples annually. The present work evaluated a prestorage conditioning treatment to protect against this physiological disorder. Results will allow the long storage of apple cv. “Granny Smith,” benefiting growers, exporters, shippers and distributors of this horticultural product.     

INFLUENCE OF 1-METHYLCYCLOPROPENE AND NATURESEAL ON THE QUALITY OF FRESH-CUT "EMPIRE" AND "CRISPIN" APPLES

Wounding during processing triggers physiological reactions that limits shelf life of fresh‐cut apples. Exposure of “Empire” and “Crispin” apples at harvest to the ethylene antagonist, 1‐methylcyclopropene (1‐MCP), on the maintenance of fresh‐cut quality was evaluated in combination with post‐cut dipping of NatureSeal^TM Efficacy of 1‐MCP on fresh‐cut physiology and quality depended on the storage duration and apple cultivar. Ethylene production of apple slices was inhibited by 1‐MCP but not by NatureSeal. Total volatiles produced by fresh‐cut apples were not affected by NatureSeal but by 1‐MCP when 1‐month stored “Crispin” apples were used. 1‐MCP influenced the quality attributes of fresh‐cut slices prepared from apples stored either 4 months in cold storage or 6 months in controlled atmosphere. Enzymatic browning and softening of the cut‐surface, TSS and total microbial growth were suppressed by 1‐MCP in “Empire” apples. The influence of 1‐MCP on quality attributes in “Crispin” apple slices was marginal.     

EFFECT OF SOME GAS MIXTURES ON STORAGE QUALITY OF PLUMS1

Plums were stored in controlled atmospheres (CA) with five gas mixtures of the following O₂:CO₂ percentages; 1:1, 1:4, 4:4, 2:2 and 4:1, for 37 days at 2.5–3C. Fruit treated with CA displayed very low decay incidence at the end of the storage period plus 2 days ripening at 22C in air, in comparison with a very high decay incidence (88%) for control fruits. CA-treated fruit ripened normally, but slowly, after 2 days in ambient conditions. There were no clear differences among CA treatments in the quality attributes of total soluble solids, acidity, firmness or color. Treatment with 1% O₂ nd 4% CO₂, however, resulted in slightly firmer fruit, with higher acidity than the untreated checks.     

CHANGES IN QUALITY ATTRIBUTES OF LONGAN JUICE DURING STORAGE IN RELATION TO EFFECTS OF THERMAL PROCESSING

Longan juice is accepted gradually by consumers due to its unique succulent, sweet and aromatic flavor. The effects of thermal processing (91C, 20 min) on quality related attributes (color, translucency, total soluble solids, total acidity, reducing sugars, ascorbic acid, phenolic compounds, protein and pectin) of longan juice during storage at low temperature were investigated. The heat-treated longan juice had a higher translucency and lower concentrations of pectin, phenolic compounds and proteins of longan juice, compared with the nonheat-treated juice. Furthermore, the thermal processing maintained higher concentrations of total soluble solids and total acidity but a lower ascorbic acid concentration. However, the thermal processing had no significant effects on reducing sugar concentration. Overall, the thermal processing maintained effectively color appearance and nutritional attributes such as total soluble solids and total acidity of longan juice during storage at low temperature. These results suggest that the thermal processing exhibits a potential for quality maintenance of longan juice.

PRACTICAL APPLICATIONS

Browning and turbidity are the major factor to influence quality of fruit juice during storage. Thermal processing is generally applied to improve quality and extend shelf life of fruit-related products. In this study, application of thermal processing exhibited potential for quality maintenance of longan juice in terms of evaluations of color, translucency and concentrations of total soluble solids, total acidity, reducing sugars, ascorbic acid, phenolic compounds, protein and pectin. The information obtained from this study could be used as a guideline for designing thermal processing to control the quality of longan juice.     

EFFECT OF 1-METHYLCYCLOPROPENE ON AROMA COMPOUNDS IN "BIG TOP" NECTARINES AFTER SHELF LIFE

“Big Top” nectarines picked at two dates (Pick 1 and Pick 2) and treated at harvest with 0 (control), 0.25, 0.5 and 1.0 µL/L 1‐methylcyclopropene (1‐MCP) when fruit ripening had already started were kept at 20 C until control fruit softened. Ethylene production was lowered by 0.25 and 1.0 µL/L doses in Pick 1 fruits and by all the doses in Pick 2 fruits. Fruit softening was delayed, but at the end of shelf life, treated fruits were as soft as the controls. Total volatile production was lowered by 0.25 and 1.0 µL/L doses in Pick 2 fruits. 1‐MCP influenced the aroma composition at the end of shelf life, yet it was not always dose dependent. Consequently, 1‐MCP changed fruit odor pattern by influencing the distribution of lactone odor units, the major odor contributors, reducing the “overmature” note and enhancing the “fresh” note.     

CHANGES IN THE RESPONSE TO GIBBERELLIC ACID OF BARLEY ENDOSPERM SLICES DURING STORAGE

Endosperm slices representative of freshly harvested as compared with stored barleys produce relatively little α-amylase when treated with gibberellic acid (GA). The response is improved by suitable storage, by heating or by procedures which increase oxygen supply to the aleurone cells. No difference could be detected in the response to GA of the dehusked corns of the two types of barley. It appeared that the outer coverings of the freshly harvested barley restrict the permeability to oxygen to a greater extent than those of stored barley, possibly because of higher microbial activity.     

QUALITY CHANGES IN APPLE JUICE AS RELATED TO NONTHERMAL PROCESSING

Fresh apple juice was preserved using ultrafiltration and high voltage pulsed electric fields as nonthermal preservation techniques. Changes in quality attributes such as soluble solids, pH, acidity and color were verified for both processes. Changes were tested in terms of membrane pore, transmembrane pressure and recovery percentage for the ultrafiltration treatments, as well as in terms of electric field strength and number of pulses for the pulsed electric fields experiments. Among the quality attributes investigated, soluble solids, pH and acid content did not show significant differences, while color was significantly different for both nonthermal techniques. For the ultrafilteredjuice, a browning trend was observed, whereas for the pulsed electric treated juice an opposite, lightening, tendency was present.     

RELATIONSHIP OF TREATMENT OF FRESH STRAWBERRIES TO THE QUALITY OF FROZEN FRUIT AND PRESERVES1

‘Cardinal’ strawberries were hand picked and stored 1 day at 21°C to enhance softening. Three separate preprocessing experiments were conducted to determine the effects of style of pack, 0.18% calcium (Ca) dips, 0.3% low methoxyl pectin (LMP), 40° Brix sucrose dips, heat of 70°C, vacuum at 172 mm Hg and drying to 70% moisture on quality and firmness of frozen-then-thawed and preserved strawberries. The greatest firming effect on frozen-then-thawed fruit was due to Ca and pectin. Sliced fruit was firmed more than whole fruit by the Ca and pectin treatments. Drained weight loss was reduced by pectin, Ca, sucrose, heat and vacuum in frozen-then-thawed fruit. Drained weight losses were the same or greater among treatments in preserves. The firmness and wholeness of preserves was increased by Ca, vacuum, 40° Brix sucrose, heat and to a lesser extent drying, but individual effects were not additive. The drying treatment reduced color quality.     

SALIVARY SECRETION IN RESPONSE TO MASTICATION OF CRISP BREAD1

Using a precision sialometer, unilateral parotid saliva was collected from six subjects while they masticated and swallowed pieces and powders from four types of Swedish crisp breads. Significantly more saliva was required for oral manipulation of the powders than for the corresponding pieces, as the greater surface area of the former required more saliva for lubrication in preparation for deglutition. Significant differences were observed in response to the four types of bread, related to both their texture and their taste. Despite wide among-subject variation in the amount of saliva secreted, there was agreement in all cases on the direction of the response. The results indicate that the measurement of the relation between the amount (and possibly the composition) of saliva secreted and the texture and chemical properties of foods can be quantitated, and merits further investigation.     

延(边)黄牛发酵牛肉干贮藏期间品质研究

对发酵牛肉干与传统牛肉干在贮藏期间品质进行研究.发酵牛肉干分别用泡菜汁、植物乳杆菌作为发酵剂.将乳酸菌发酵牛肉干、泡菜发酵牛肉干和传统牛肉干真空包装后放入4℃冰箱中贮藏6个月,每个月对其细菌菌落总数、一般营养成分(水分含量、粗蛋白含量、粗脂肪含量、粗灰分含量)及嫩度进行测定.结果表明:3种牛肉干细菌菌落数均未超标;水分有所下降,灰分、蛋白质和脂肪含量相对升高;发酵牛肉干能明显改善牛肉干嫩度.     

CHANGES IN THE ORGANOLEPTIC QUALITY OF SHAMOUTI ORANGES DURING THEIR RIPENING SEASON1

The quality of Shamouti oranges was determined by taste panels before and after storage. Unstored oranges were given the same scores when tasted as peeled segments and as fresh juice; stored oranges were given higher scores when tasted as juice than when tasted as segments. Multiple regression of taste quality score on the Brix, Acidity and Maturity Ratio leads to localization of peak organoleptic maturity conditions.     

RESPONSE TO ELECTRICAL STIMULATION AND POST-MORTEM CHANGES IN TURKEY PECTORALIS MAJOR MUSCLE

SUMMARY– Muscle samples were obtained from 20 turkey hens 5 min postexsanguination for the determination of sarcomere length, response to electrical stimulation, and time-course of rigor mortis. Additional samples were obtained from the opposite (undisturbed) pectoralis major muscle at 1, 2, 6 and 24 hr post-mortem for the determination of sarcomere length. Birds were divided into three groups based on the time to complete rigor mortis: (1) slow, > 125 min; (2) fast, <50 min; and (3) intermediate, 50–125 min. Birds that displayed a long time course of rigor mortis had a low threshold of response (9v) and a long duration of response (106 seel to electrical stimulation. Conversely, muscles which become inextensible within 50 min displayed a high threshold (123v) and low duration (8 sec). Muscles with intermediate rates of rigor had intermediate threshold (58v) and duration (50 sec). Increase in sarcomere length occurred within 1 hr post-mortem in the fast-rigor group, 2 hr in the intermediate-rigor group and 6 hr in slow-rigor birds. A similar experiment conducted on 24 toms indicated that postexsanguination struggling resulted in a decreased time course of rigor, elevated threshold and shortened duration of response to electrical stimulation. Strugglers displayed a more rapid (P<.01) post-mortem increase in sarcomere length than non-strugglers. The results suggested that in some presently-used commercial turkey processes, some of the carcasses are frozen with muscles in a prerigor, short-sarcomere state.     

CHANGES IN QUALITY OF DEHYDRATED KIBBLED ONIONS DURING STORAGE

SUMMARY— Dehydrated kibbled onions. of the Egyptian variety, containing 4-5% moisture, were stored under different conditions and their keeping quality as influenced by storage variables determined. 3 packaging materials, namely cans, polyethylene and Saran pouches were used. Samples were stored at temperatures of 15, 25 and 35°C at 44% relative humidity for 39 wk. Temperature of storage was found to have the largest effect on product quality. The can package was found to be superior to the flexible pouches; however, Saran pouches could be used under certain conditions. Moisture content increased significantly in polyethylene pouches at all temperatures, but in Saran pouches only at 25° C Absorbance of onion extracts, as measure of browning, increased significantly with storage temperature and to a smaller extent due to packaging materials. Products in polyethylene deteriorated most, while the difference between Saran- and can-packed products was small. A similar trend in results was found in tristimulus color determinations. All products stored at 15° C and those in cans at 25°C were found to be of good organoleptic quality. The pyruvic acid development potential could not be used as a sensitive indicator for determination of product quality.     

EFFECT OF COLD STORAGE ON THE QUALITY CHARACTERISTICS OF ‘AU-RUBRUM’ PLUMS1

The effect of cold storage (0°C) and maturity on the physical, chemical and sensory characteristics of plums (cv. ‘AU-Rubrum’) was determined. The size, weight, soluble solids and total sugar contents of the more mature fruit were significantly higher (P<0.05) and the “L” and hue angle were significantly lower (P<0.05) than plums in the less mature class. ‘AU-Rubrum’ fruit contained glucose, fructose and sorbitol but had no sucrose. Artificially ripening fruit at 20°C had a significant effect (P<0.01) on all color values for both maturity 1 and 2 fruit. The titratable acidity and sugar contents of the fruit ripened at 20°C were lower for ripened than for unripened fruit. Storage of the plums at 0°C for 5 weeks followed by subsequent ripening at 20°C had no significant effect on physical, chemical or sensory characteristics. Data indicate that ‘A U-Rubrum’ plums which have one-half red ground color (maturity 1) will develop full color and complete the normal ripening process. Data also indicate that the plums can be stored for at least 5 weeks at O°C without loss of quality and that the cultivar has potential for shipping to distant markets.