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Shelf life of minimally processed pineapple

M. N. Latifah, H. Abdullah, M. Mohd. Selamat, M. Habsah, Y. Talib, K. M. Rahman and H. Jabir

Abstract

Shelf life of minimally processed pineapple packed using polypropylene container was evaluated during storage at temperatures of 25 °C and 10 °C. Samples were evaluated daily for the rate of respiration, ethylene production,
weight loss, chemical compositions (pH, TTA, TSS and ascorbic acid) and gases (CO₂, O₂ and C₂H₄) inside the package. The accumulation of CO₂ showed an increasing trend when the minimally processed pineapple was stored at 25 °C (0.2–1.2%) and at 10 °C (0.2–1.6%). Similar trend was observed in the O₂ level during storage at 25 °C (2.5–14.5%). However, at 10 °C the level of O₂ decreased (16.5–6.2%). Respiration rates of minimally processed pineapple increased with duration of storage, however, ethylene production was not detected. A great increase in the weight loss (0.06–0.28%) was observed from day 1 to day 2 storage at 25 °C. It took about 4 days for this range to be observed during storage at 10 °C. The pH value increased (3.63–3.93) during storage at 25 °C, whereas the TTA, TSS and ascorbic acid values decreased. However, at 10 °C the chemical compositions decreased by the end of the storage period. At 25 °C, the minimally processed pineapple can be stored for 2 days whereas at 10 °C, the shelf life was 7 days.

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Spatial distribution of some major arthropods and sampling procedures for Aphis gossypii Glov. in polyculture system comprising chilli, brinjal and leucaena plants

Abstract

In preventing crop losses due to chilli veinal mottle virus transmitted by Aphis gossypii on chilli plants, a polyculture system is known in many cases to suppress pests through predation by Menochilus sexmaculatus. However, information on spatial distribution of major pests and predators in polyculture crop system is little known. Yet such information is essential in developing sampling plans for pest management. The spatial distributions of two pest species, A. gossypii on chilli and brinjal plants and Heteropsylla cubana on leucaena plants; and one predator species, M. sexmaculatus, were analyzed with respect to different culture methods and life stages using Taylor’s Power Law (b coefficient) and Iwao’s mean crowding index (β coefficient). Subsequently,
Taylor’s coefficients were used in developing the Green’s sequential plan for A.gossypii for each culture method. This study indicates that all arthropod categories were clumped, with β and b values significantly larger than 1. On regressing the variance on the mean density, Taylor’s Power Law indicates the best fit with higher r2 and lower standard errors compared with Iwao’s mean crowding. The immobility of aphid nymphs and wingless aphids tends to result in high aggregations, whereas decreasing aggregations in winged aphids are due to the flight ability. In developing a sampling plan, monoculture requires a smaller sample size than that required by diculture and triculture. Population density of insect species in monoculture is higher than those in diculture and triculture. The Green’s plan required smaller sample size than fixed-sample-size plan. As the precision level is decreased from 0.20 to 0.30, the sample size decreases from 44 to 12 in monoculture, from 41 to 14 in diculture, and from 51 to 17 in triculture. Each type of culture yielded a high percentage of actual precision level lower than the optimal precision level. The result obtained indicates that the Green’s plan is feasible and applicable in pest management program for A. gossypii with a precision level of 0.30.

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Floral biology and the compatibility system in ciku cv. Jantung (Manilkara achras)

J. Indu Bala

Abstract

The investigation was initiated to identify and understand fully the reproductive biology of ciku cv. Jantung. Trials were conducted to determine the floral biology, efficiency of pollen transfer and the system of pollination. Based on the changes in the external morphology of ciku flower buds, four stages of floral development were identified; stages 1–3 at bud stage and stage 4 at flower opening. At stage 2, the anthers dehisced and released pollens. The pollens only became viable and functional at stage 4, i.e. at anthesis. The stigma was receptive from stage 2 to 3 but was at its peak at stage 3, i.e. a day before the flower opened. These results therefore showed that there was little or no overlapping between the staminate and the pistillate phases (temporal separation) of ciku cv. Jantung. This was further confirmed with the pollination trial where only 4.8% of fruit set was obtained when the flower buds were bagged. The presence of temporal separation in ciku cv. Jantung limits within-flower pollination and therefore favours outcrossing. However, the relatively high fruit set (65%) obtained from the assisted self-pollination trial further suggests that ciku Jantung is self-compatible. Although within-flower pollination is limited, between flower pollination can occur extensively as the flowers are self-compatible.

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CHANGES ASSOCIATED WITH DIFFERENT STAGES OF HARVESTING AND RIPENING OF EKSOTIKA PAPAYA AT AMBIENT TEMPERATURES

P.F. LAM and M.Z. ZAIPUN

Abstract

Eksotika papaya fruit were harvested at stages of different colour indices and were ripened at ambient temperature. The colour indices were classified as I : all green on the skin surface, 2 : green
w i t h a t i n g e o f y e l l o w , 3 : m o r e g r e e n t h a n y e l l o w , 4 : m o r e y e l l o w t h a n g r e e n , 5 : y e l l o w w i t h a t i n g e of green and 6 = all yellow. Fruit with colour indices 1*3 and 4-6 were significantly different in their firmness. The shelf life of all fruit except those of colour index 6 ranged from five to nine days. Less mature fruit had a longer shelf life. In sensor evaluation, fruit colour indices 4-6 were acceptable with
colour index 5 being the most preferred. The total soluble solids, pH and total titratable acidity were 9.5%-16.5%,5.0*5.7 and0.107c-0.25% (anhydrousc i t r ic acid equivalent )i n fruit at variouss stages of colour indices.

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