INFLUENCE OF HIGH TEMPERATURE STRESS ON POSTHARVEST QUALITY OF PROCESSING AND NON-PROCESSING TOMATO CULTIVARS

Tomato fruits from a processing cultivar,‘Dorado’and a non-processing cultivar, ‘Star Pak’, were subjected to three prestorage heat treatments over a 5-h period under unshaded (34±2C), shaded (29±2C) and pre-cooled (20±2C) conditions followed by storage for 18 and 36 days at 20C. Terminal symptoms of heat injury and disease infection were evaluated in relation to changes in physical, physiological and chemical characteristics of the fruits during storage. Unshaded fruits demonstrated effects of heat injury resulting in reduced bioelectrical resistance, increased electrolyte leakage, increased total acidity and decreased total soluble solids during storage at 20C. Pre-cooling and shading proved to be effective methods to remove or prevent accumulation of field-heat and minimize heat injury. Pre-cooling was most effective, accounting for 28 % and 14% less infected fruits for ‘Dorado’and ‘Star Pak’, respectively, compared with unshaded fruits, after 36 days storage at 20C.     

QUALITY ATTRIBUTES, PECTOLYTIC ENZYME ACTIVITIES AND PHYSIOLOGICAL CHANGES DURING POSTHARVEST RIPENING OF NECTARINE

The postharvest ripening at 20C and 90–95% RH for 10 days of ‘Armking’ nectarine grown in a greenhouse was investigated over two seasons. Firmness, titratable acidity, ascorbic acid, pH and maturity index were all adequate to stablish the rate of ripening. However, soluble solids content and reducing and non-reducing sugars showed no significant changes. It took about 10 days for very early ripening fruit (100 g weight and 82 N firmness) and 6 days for normal early ripening fruits (115 g weight and 46 N firmness), both harvested at preclimacteric stage, to become eating ripe (near 20 N). Total weight loss and decay after 10 days was approximately 11%. During ripening there was a temporal coincidence among higher rates of ethyleneproduction, higher pectinmethylesterase (PME) and polygalacturonase (PG) activities, lower firmness and acidity and higher maturity index. PME and PG activities increased during ripening, with a highly negative linear correlation between activities of the two enzymes and firmness. In very early ripening fruit, PME activity was more closely related to softening than PG, whereas in normal early ripeningfruit, PG activity was slightly more closely linked to the loss offirmness than PME.     

COMPARISON OF VOLATILE COMPOUNDS IN TWO SEASONS IN APPLES: GOLDEN DELICIOUS AND GRANNY SMITH

Fruit of varieties Golden Delicious and Granny Smith, were harvested at commercial maturity in two consecutive years (1993 and 1994). The aroma components obtained were analyzed by the dynamic headspace method and quantified by gas chromatograph-mass spectrometry. In Golden Delicious the total esters represented more than 80% of the total volatile components in both years, consistent with Drawert's classification (1975). However, Granny Smith did not, since the esters made up 72 and 88% of total volatiles in the years 1993 and 1994, respectively. The aroma components are different in class and quantity and give a characteristic sensorial perception for each type of fruit and variety. In Golden Delicious, ethyl propionate and butyl acetate gave a fruity aroma in 1993 and ethyl acetate, ethyl propionate and propyl acetate were the predominant compounds in 1994. In Granny Smith the aroma composition was slightly different in the two years. In 1993 the aromatic profile did not show the predominance of any compound, while in 1994 it was more fruity due to the higher content of ethyl propionate and propyl acetate.     

INFLUENCE OF CONVENTIONAL CLARIFICATION AND ULTRAFILTRATION ON THE PHENOLIC COMPOSITION OF GOLDEN DELICIOUS APPLE JUICE

Abstract The effects of conventional clarification and ultrafiltration techniques on the phenolic composition of apple juice was studied. Since the health benefit of fruits and fruit juices have been ascribed, in part, to the phenolic antioxidants, it is very important to know what the effects of processing steps are on the level of phenolic compounds in fruit juices. The total losses of phenolic compounds were determined to be 28% and 7% during conventional clarification using gelatin and bentonite, and ultrafiltration, respectively. A total of 14 phenolic compounds were identified in apple juice prepared from Golden Delicious apples. The phenolic compounds were found to be based mainly on hydroxycinnamic acids (∼ 50% of total phenolics) and chlorogenic acid was found to be the major phenolic compound with its concentration as high as 465.45 mg 1⁻¹ in raw apple juice.     

THE INFLUENCE OF POSTHARVEST STORAGE, TEMPERATURE AND DURATION ON QUALITY OF COOKED BROCCOLI FLORETS

Fresh broccoli heads (Brassica oleracea L. var, italica) were stored at 1C, 5C or 10C from 0 to 14 days. After this postharvest treatment, heads were cut into florets, which were given a short heat treatment and afterwards stored in plastic bags for a period of 8 days. Storage time and storage temperature before processing affected the texture and color, chlorophyll, vitamin C and β-carotene of cooked florets. The texture of cooked florets was highly correlated with water loss of the raw heads. Significant correlations were found between yellowness, instrumental color measurements and chlorophyll for cooked broccoli. Vitamin C content was affected significantly by subsequent chill temperature storage of cooked florets, which previously were stored at 5C for a period from 0 to 14 days. After 3 or 8 days of subsequent chill temperature storage of cooked broccoli florets, the vitamin C content seemed to reach almost the same level irrespective of the duration of storage of the raw heads, β-carotene content of cooked broccoli florets was stable when raw broccoli heads were stored at 1C and 5C, whereas it decreased towards the end of the storage period when the heads were stored at 10C. After cooking, β-carotene content remained stable during subsequent chill temperature storage.     

INFLUENCE OF ATMOSPHERIC OXYGEN AND OZONE ON RIPENING INDICES OF NORMAL (Rin) AND RIPENING INHIBITED (rin) TOMATO CULTIVARS1

ABSTRACT Ethylene (10ppm) dependent mediation of normal and mutant (rin) tomato fruit ripening was promoted by 100%oxygen, 3.7 pphm ozone, or their combination. All ripening indices studied (respiration, chlorophyll degradation, carotenoid accumulation, softening, and aroma development) were promoted by oxygen and/or ozone. Ozone also acted independent of ethylene in promoting chlorophyll degradation and aroma development in normal fruit, but did not appreciably affect these quality attributes in mutant fruit. Lycopene accumulation in normal and mutant fruit and aroma formation in normal fruit were promoted to a greater extent by ozone than were other ripening indices. Mutant (rin) fruit contained 27% of the lycopene that was present in normal (Rin) fruit after ripening in O₂ containing 10ppm ethylene and 3.7 pphm ozone, whereas they contained only 3%of the lycopene in normal fruit after ripening in air containing 10ppm ethylene.     

NO减压处理对富士苹果采后生理特性的影响

以"富士"苹果为试材,研究了常温贮藏条件下N0(一氧化氮)减压(0.5个大气压,50.662 5 kPa)处理对果实采后生理的影响.结果表明:NO减压处理可延缓果实可溶性固形物的降低;显著抑制果实乙烯释放量,显著降低呼吸强度;减缓果肉硬度下降;显著延缓丙二醛(MDA)含量的升高,从而降低膜脂过氧化程度;提高了POD的活性,减少H2O2的积累.结果表明:适宜浓度NO处理可明显改善其贮藏品质,延缓衰老.     

THE INFLUENCE OF MICROWAVES AND SELECTED MANUFACTURING PARAMETERS ON APPLE CHIP QUALITY AND ANTIOXIDANT ACTIVITY

Apple chips belong to the group of low-processed food products and are an interesting alternative to currently popular snacks. The aim of the work was to estimate the influence of chosen technological parameters on quality and antioxidant properties of apple chips. Thickness of apple slices, drying temperature and initial microwave treatment were analyzed.
On the basis of experimental data, it was established that the drying temperature of 90C was optimal for obtaining products with advantageous sensory value. Apples before drying should be cut into slices 3.5 mm thick and immediately soaked in a solution containing saccharose, apple concentrate, citric acid and SO₂. It was shown that microwave pretreatment of apple slices (150–300 W, 5–10 min) shortened the drying time by about 25% and increased the antioxidant potential by about 30%.

PRACTICAL APPLICATIONS

Because of the increasing incidence of civilization diseases, worldwide interest in snack products that are low in calories and healthy is still growing. The optimum parameters of apple chip production (slice thickness and drying temperature) to obtain a product of high antioxidant potential are presented in this study. It is also shown that application of microwave pretreatment enabled us to shorten the process duration and to reduce the production costs while antioxidant activity remained at a relatively high level.     

EFFECTS OF PEEL ADDITION AND STORAGE ON QUALITY OF GOLDEN APPLE (SPONDIAS CYTHEREA SONN) HOT SAUCES

Fresh, frozen or brined golden apple puree (Spondias cytherea) was utilized in hot sauces. The effects of puree, fruit peel addition, and storage on quality of sauces was investigated. Base formulation, (%) consisted of golden apple puree (50), water (25), vinegar (10), peppers (6), sucrose (4) aromatic spices (2), citric acid (1.1) sodium chloride (1.0), xanthan gum (0.8) and sodium benzoate (0.1). Processing of hot sauces was at85–90C for15–20 min followed by hot‐filling into glass bottles. Fruits were acceptable in 20% brine up to 6 weeks at28–31C. Physico‐chemical quality of sauces varied due ( >P <0.05) to fruit puree. Sensory quality did not vary (< P >0.05) in sauces with 0% or 5% peel, however, sauces of 100% peel were more yellow ( P <0.05), had lower total soluble solids ( P <0.05) and were less acceptable ( P <0.05). The shelf‐life of sauces was at least 90 days at28–31C or 5C.     

EFFECT OF EVAPORATIVE COOLING STORAGE ON RIPENING AND QUALITY OF TOMATO

Tomatoes (Lycopersicon esculentum Mill cv. Rupali) ripened in evaporative cooling (EC) storage conditions (20°C–25°C, 92–95% RH) were compared with control fruits stored under room conditions (28°C–33°C, 45–65% RH) during summer in Mysore. EC ripened tomatoes on the 15th day reached 100% ripening index (RI) with a value of 2.48 for the ratio of redness to yellowishness (a/b) and hue angle (θ) of 22.1° whereas the control tomatoes on the same day reached a maximum 83.3% RI with a/b ratio of 1.59 and a hue angle of 32.9°. Higher development of chroma and total color difference were exhibited by EC stored tomatoes than control samples. The lycopene content of EC ripened fruits double that of the control. EC stored fruits showed lower values for rupture and shear stresses. The rate of moisture loss for control fruits was 6.5 times as great as for EC stored tomatoes.     

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.