EFFECT OF POSTHARVEST HOT AIR AND FUNGICIDE TREATMENTS ON THE QUALITY OF 'MARADOL' PAPAYA (CARICA PAPAYA L.)

Papaya (Carica papaya L.) fruit is very perishable with a maximum postharvest life of 4 weeks. The effect of forced moist (100% RH) or dry (50%) hot air with or without Thiabendazole (TBZ at 1.2 g active ingredient/L) on the chilling injury (CI), fungi development and quality of ‘Maradol’papaya fruit stored at 5C or 20C for up to 42 days was investigated. Moist hot air at 48.5C or 50C for 4 h caused fruit injury. Dry air at 48.5C for 4 h, alone or in combination with TBZ, decreased CI intensity and fungi development, and the best effect was achieved by combining dry heat treatment and TBZ, without causing negative effects on fruit quality and without causing heat injury. Hot air treatment, especially in combination with TBZ, decreased growth of inoculated Colletotrichum gloeosporioides. Trehalose was not detected in papaya, probably due to the presence of trehalase. Hot water treatment, with or without TBZ, did not cause any negative effect on the content of β-carotene and lycopene.     

EFFECT OF COOLING DELAY AT HARVEST ON BROCCOLI QUALITY DURING POSTHARVEST STORAGE

Broccoli (cv ‘Green Duke’) was grown, harvested and cooled prior to simulated handling and storage. Delays of cooling were 0.5 and 3.0 h in one experiment and 0.5, 1 and 2 h in a subsequent experiment. Significant losses in market life of fresh broccoli were noted within the 3 h cooling delay period. Floret opening was the limiting visual quality characteristic in most treatments. Turgor was more limiting than color in all observed treatments. Using a systems approach a vertically-integrated broccoli handler could project the effects of cooling delays on shelf-life expectations within the prescribed handling system.     

As (V) biosorption in an aqueous solution using chemically treated lemon (Citrus aurantifolia Swingle) residues

The use of biosorbents to remove metals and metalloids from contaminated water systems has gained great usage in various parts of the world. The objective of the current study was to test lemon peels as biosorbents for As (V). Lemon peels were chemically characterized and arsenic contact experiments were performed to determine the adsorption capacity of the peels using different empirical models. The model that fit the experimental data was the Lagergren empirical model with a correlation coefficient of R= 0.8841. The results show that lemon peels were able to retain 474.8 μg of As (V)/g of biosorbent. PRACTICAL APPLICATION: Lemon agro-industrial waste can be useful in the removal of heavy metals, such as arsenic, from aqueous media.     

温度对豇豆采后保鲜效果影响的研究

为探明贮藏过程中温度对豇豆保鲜效果的影响,研究了温度与豇豆在贮藏过程中的外观变化及其生理指标变化的关系.结果表明:豇豆豆荚在室温(30℃～35℃)下的贮藏寿命为4d.低温(10℃)贮藏能够降低豇豆豆荚的水分散失,减缓豆荚中VC和叶绿素含量的下降,抑制其呼吸速率,维持豆荚细胞膜的完整性,使豇豆的贮藏寿命延长到12 d.     

EFFECT OF DIFFERENT POSTHARVEST TREATMENTS ON ANTINUTRITIONAL FACTORS IN SOME COMMONLY CONSUMED LEAFY VEGETABLES IN CAMEROON

Effect of squeeze-washing, boiling in kanwa (a local alkaline salt) and drying of the leaves of some leafy vegetables ( Vernonia colorata, V. calvoana var. bitter, V. calvoana var. nonbitter and V. amygdalina ) consumed in Cameroon on antinutritional factors were evaluated. Results show that values for polyphenols were high in the unprocessed leaves. These values were reduced by 84.5% in V. amygdalina during processing. Sun drying and oven drying at 75C also caused slight losses ( P <  0.05) in polyphenols. Saponin values were high in these four species but were considerably reduced by processing, rendering the nutrients in these leafy vegetables more bioavailable. Reductions ( P <  0.05) were also observed for proteins as a consequence of processing by squeeze-washing and use of kanwa. Similar trends were found for oxalic acids. Losses of up to 73% oxalic acids were observed in samples after processing. With the exception of drying, significant losses in minerals were observed due to these processes. This study, therefore, suggests the use of some of these different processing techniques to reduce the levels of antinutritional factors in these leafy vegetables.

PRACTICAL APPLICATIONS

The different species of leafy vegetables ( Vernonia ) are potentially rich sources of provitamin A, vitamin C and minerals. Use of appropriate processing and preservation technology makes these vegetables available at off seasons and in cities of high demand and improves on the actual nutritional value to the consumers. Industrially, these vegetables can be processed by squeeze-washing and the use of minimal quantities of kanwa and possibly dried at 45C for use in urban centers.     

STUDIES ON POSTHARVEST PHYSIOLOGY AND THE STORAGE TECHNOLOGY OF MANGO (MANGIFERA INDICA L.)

Mango (Mangifera indica L. cv. Hongxiangya and Wacheng) was chosen to study the effect of postharvest biological characters in different storage conditions. The determining items included respiratory rate, total sugar, vitamin C (Vc) content, firmness, polyphenol oxidase (PPO) and peroxidase (POD). The results showed that both 8 and 11C were the better storage temperatures, and the storage life would last 50 days in this situation. The respiration rate increased quickly between the 16th to the 22nd days; the peak values were the 28th and 25th days at 8C for Hongxiangya and Wacheng, respectively. The flesh firmness decreased dramatically at 6 days after harvest. Total sugar content, Vc content, PPO and POD increased at first and then decreased. The color changed from green to yellow with the increase of carotenoids content. After treatment with thiabendozole and iprodione, the number of rot fruits was markedly lower than the other treatments. The best temperature is 11 and 14C for Hongxiangya and Wacheng, respectively. The rot rate is 6.77 and 8.33% with 1,000‐ppm iprodine treatment after 50‐days storage.     

NO处理对采后猕猴桃贮藏性及叶绿素含量的影响

以“秦美”猕猴桃为试材,研究了不同浓度NO处理对猕猴桃贮藏效果的影响,结果表明,适当浓度的NO处理可以延缓呼吸高峰的出现,降低果实的呼吸峰值,延缓果实硬度的下降,同时使果实中丙二醛(MDA)及H2O2含量低于对照,本试验以1.0μmol/LNO处理的效果较好。处理后的果实叶绿素降解速率比对照慢,尤其是在贮藏第四周后效果明显。但对可溶性固形物、可滴定酸及pH值的影响,对照与处理并无差异。     

CONTROLLED ATMOSPHERE STORAGE AND EDIBLE COATING EFFECTS ON STORAGE LIFE AND QUALITY OF TOMATOES

Tomatoes at pink stage maturities were coated with Semperfresh^TM edible fruit coating which is composed of sucrose esters of fatty acids, sodium carboxymethyl cellulose and mono-diglycerides of fatty acids. One group of coated and uncoated tomatoes were stored at 23 × 2C under air atmosphere, another group was stored at 12C under air atmosphere and third group was stored at 12C, 93–95% RH in a controlled atmosphere (CA) containing 3% CO₂, 3% O₂ and 94% N₂. Samples of tomatoes were analyzed for firmness, weight loss, titratable acidity, pH, soluble solids, sugars, ascorbic acid and lycopene to examine changes in quality during storage. Semperfresh^TM edible fruit coating was found to be significantly effective at both storage temperatures (23 × 2C and 12C) in air to delay changes in firmness, titratable acidity, pH, soluble solids, sugars, ascorbic acid and lycopene. Semperfresh^TM fruit coating reduced fruit weight loss as compared to fruit without coating but the difference between coated and uncoated tomatoes was not significant. Shelf-life of pink tomatoes was increased 3 days at 23 × 2C and 6 days at 12C in air by coating. CA storage delayed compositional changes in tomatoes significantly as compared to air storage of coated and uncoated tomatoes. CA storage also had a significant potential for reducing weight loss and microbial spoilage. Tomatoes were stored 40 days in CA. Coated and uncoated tomatoes exhibited the same results in CA.     

Pectinesterase extraction from Mexican lime (Citrus aurantifolia Swingle) and prickly pear (Opuntia ficus indica L.) peels

Extracts from Mexican lime (Citrus aurantifolia Swingle) and prickly pear (Opuntia ficus indica L.) peels were tested for their pectinesterase activity. A factorial design was applied in this study as a method for enzyme extraction in which the variables were the source of enzyme (prickly pear and Mexican lime peels) and the NaCl solution concentration (0–3.0 M). In all cases, enzyme extracts obtained using the same NaCl concentration from lime peel showed higher activity than extracts from prickly pear peel. NaCl concentration influenced the pectinesterase extraction process in both cases. Maximum enzyme activities were obtained with NaCl 0.5 M and 1.0 M for Mexican lime and prickly pear peels, respectively.     

EFFECT OF HIGH PRESSURE TREATMENTS ON PEROXIDASE AND POLYPHENOLOXIDASE ACTIVITIES

The effects of hydrostatic pressure of 1–9 kbar on peroxidase (POD) and polyphenoloxidase (PPO) activity were studied. Trials were carried out on crude enzymatic extracts obtained from carrots and apples as the sources of POD and PPO, respectively, with different pH values (from 4.5 to 7.0). In both cases pressurization caused a remarkable enzyme activation after 1-min treatments carried out at 3–5 kbar, while a complete enzyme inactivation was observed at 9 kbar. The pH values of the crude enzymatic extracts seemed to affect the degree of activation and/or inactivation due to different pressure levels. A slight recovery in enzyme activity was measured for POD samples during the first 24 h of storage after the treatments.     

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.     

EFFECT OF HIGH HYDROSTATIC PRESSURE, GAMMA-IRRADIATION AND COMBINATION TREATMENTS ON THE MICROBIOLOGICAL QUALITY OF LAMB MEAT DURING CHILLED STORAGE

The effect of gamma irradiation (1.0 kGy) and high hydrostatic pressure (200 MPa for 30 min), either alone or in combination on the shelf-life of lamb mince meat at 0–3C was studied. Untreated control samples initially had total microbial counts of 10⁵ CFU/g, 10² CFU/g of coliforms and 10⁴ CFU/g of Staphylococcus spp. Coliforms were eliminated by all the treatments . Staphylococcus spp. however, were reduced only by 1 log cycle when treated with irradiation alone and high pressure alone. These species were a mixture of mannitol-fermenting and mannitol-nonfermenting strains. In samples subjected to the combination treatment , Staphylococcus spp. appeared only after 3 weeks of storage and all were mannitol-nonfermenting. On the basis of microbiological and sensory quality, the shelf-life of the control sample was less than 1 week. All treated meat samples had a shelf-life of 3 weeks, but only combination treated samples were free from potentially pathogenic Staphylococcus spp .