1-Methylcyclopropene Delays Softening in Tomato Slices

I-Methylcyclopropene (1-MCP) has the potential in tomato to reduce ethylene-associated changes in texture. Tomato cv. 'Revolution' was harvested at the 'pink' maturity stage and whole fruit treated with 0, 0.1, 1.0 or 10.0 µL.L-' 1-MCP at 20 "C for 12 h. Slices of 7-mm thickness were cut using a commercial slicer, and the slices stored in vertical stacks in plastic containers at 5°C for 7 days. The application of 1-MCP reduced both ethylene production and respiration rate of slices and resulted in firmer pericarp firmness. Ethylene production was 24%, 40%, and 62% lower following 0.1, 1.0, 10.0 µL L-' 1-MCP, respectively, compared with controls. In addition, respiration rate was reduced 6%, 10% and 20% by those 1-MCP treatments. 1-MCP treatments produced 20%, 34%, and 24% higher pericarp firmness, respectively, than in fruit not treated with 1-MCP.

Effect of an Ethylene Absorbent on Quality of Tomato Slices

Ethylene production is stimulated during the slicing of fresh cut tomato slices. Experiments were conducted to investigate whether the inclusion of ethylene absorbents in packaging affects the quality of tomato slices cv. Revolution during storage at 5OC. ‘Pink’ maturity stage tomatoes were cut into 7mm thick slices and vertically stacked in closed glass containers for 12 days with or without Purafil® to remove ethylene. The ethylene removal treatment resulted in reduced ethylene, less CO2 accumulation, and firmer slices.

Exposure of Tomato Fruit to 1-MCP Improves Quality of Stored Slices

Maintenance of quality, such as firmness, is important during storage of fresh cut produce. This study compared the effects of I-MCP on the quality of tomato slices when intact tomatoes were treated with 1-MCP and then sliced, or tomatoes were sliced and the slices treated with I-MCP. In both instances the MCP treatment was 1 µL Lˉٰ at 20 ºC for 12 h. Tomato cv. 'Revolution' was harvested at the 'pink' stage of maturity, cut into 7-mm slices, and stored as vertical stacks in closed plastic containers at 5ºC for up to 7 days after the 1-MCP treatment. Exposure of intact tomatoes to I-MCP resulted in reduced ethylene production (31%) and firmer (22%) slices than when tomatoes were not I-MCP treated. The application of I-MCP prior to slicing of tomatoes appears a useful strategy to retain quality of stored tomato slices.

The freezing of mango slices (Mangifera indica var. Kensington)

'Kensington' mango slices were frozen with sucrose syrup, with dry sucrose and without sugar addition, using blast freezing at -30°C, and still air freezing at -18°C. According to taste panel assessment, slices frozen in syrup were best. A syrup strength of 200 g/L was sufficient to produce a high quality product. the blast-frozen slices had a higher texture score than the still air-frozen slices.

Cultivar affects browning susceptibility of freshly cut star fruit slices

Consumption of freshly-cut horticultural products has increased in the last few years. The principal restraint to using freshly-cut carambola is its susceptibility to tissue-browning, due to polyphenol oxidase-mediated oxidation of phenolic compounds present in the tissue. The current study investigated the susceptibility to browning of star fruit slices (Averrhoa carambola L.) of seven genotypes (Hart, Golden Star, Taen-ma, Nota-10, Malasia, Arkin, and Fwang Tung). Cultivar susceptibility to browning as measured by luminosity (L*) varied significantly among genotypes. Without catechol 0.05 M, little changes occurred on cut surface of any cultivars during 6 hour at 25 degrees C, 67% RH. Addition of catechol led to rapid browning, which was more intense in cvs. Taen-ma, Fwang Tung, and Golden Star, with reduction in L* value of 28.60%, 27.68%, and 23.29%, respectively. Browning was more intense in the center of the slices, particularly when treated with catechol, indicating highest polyphenol oxidase (PPO) concentration. Epidermal browning, even in absence of catechol, is a limitation to visual acceptability and indicates a necessity for its control during carambola processing. Care must be given to appropriate selection of cultivars for fresh-cut processing, since cultivar varied in browning susceptibility in the presence of catechol.

Multivariate analysis of fresh-cut carambola slices stored under different temperatures.

Quality of fresh-cut carambola (Averrhoa carambola L) is related to many chemical and biochemical variables especially those involved with softening and browning, both influenced by storage temperature. To study these effects, a multivariate analysis was used to evaluate slices packaged in vacuum-sealed polyolefin bags, and stored at 2.5 degrees C, 5 degrees C and 10 degrees C, for up to 16 d. The quality of slices at each temperature was correlated with the duration of storage, O(2) and CO(2) concentration in the package, physical chemical constituents, and activity of enzymes involved in softening (PG) and browning (PPO) metabolism. Three quality groups were identified by hierarchical cluster analysis, and the classification of the components within each of these groups was obtained from a principal component analysis (PCA). The characterization of samples by PCA clearly distinguished acceptable and non-acceptable slices. According to PCA, acceptable slices presented higher ascorbic acid content, greater hue angles ((o)h) and final lightness (L-5) in the first principal component (PC1). On the other hand, non-acceptable slices presented higher total pectin content. PPO activity in the PC1. Non-acceptable slices also presented higher soluble pectin content, increased pectin solubilisation and higher CO(2) concentration in the second principal component (PC2) whereas acceptable slices showed lower total sugar content. The hierarchical cluster and PCA analyses were useful for discriminating the quality of slices stored at different temperatures.

Reducing Browning of Fresh-cut ‘Maha’ Carambola with Chemical Additives and Low-oxygen Atmospheres

The greatest attraction to using carambola (Averrhoa carambola L.) in the fresh-cut market is the star shape that the fruit presents after a transverse cut. Carambola is well-suited for minimal processing, but cut surface browning is a main cause of deterioration. This problem is exacerbated as a result of mechanical injuries occurring during processing and is mainly induced by the leakage of phenolic compounds from the vacuole and subsequent oxidation by polyphenol oxidase (PPO) (Augustin et al., 1985). The use of browning inhibitors in processed fruits is restricted to compounds that are non-toxic, ‘wholesome’, and that do not adversely affect taste and flavour (Gil et al., 1998). In the past, browning was mainly controlled by the action of sulphites, but the use of this compound has declined due to allergic reactions in asthmatics (Weller et al., 1995). The shelf life of fresh-cut products may be extended by a combination of oxygen exclusion and the use of enzymatic browning inhibitors. The objectives of this work were to determine the effects of: (1) post-cutting chemical treatments of ascorbic, citric, oxalic acids, and EDTA-Ca; (2) atmospheric modification; and (3) combinations of the above, on the shelf life of carambola slices based on appearance, colour and polyphenol oxidase activity

Response of minimally processed carambola to chemical treatments and low-oxygen atmospheres

Fresh-cut carambola (Averrhoa carambola L.) has limited marketability due to cut-surface browning. The effect of chemical treatments (ascorbic acid, citric acid and Ca-EDTA), controlled atmosphere (0.4-20.3% O2) and the association of these processes was investigated. Post-cutting dip and low-oxygen atmospheres did not prevent discoloration or improve sensory and physicochemical parameters. However, ascorbic acid (0.5% and 1%) dips reduced polyphenol oxidase (PPO) activity during storage at 4.5 °C, with 1% ascorbic acid inducing the lowest activity. Although cut-surface browning of 'Maha' slices was not relevant, carambola slices treated with 1% ascorbic acid in association with 0.4% oxygen did not present significant browning or loss of visual quality for up to 12 days, 3 days longer than low oxygen alone (0.4% O2), thus, their quality can be significantly improved by combining both treatments.

A new culture method for lesser mealworm, Alphitobius diaperinus

A new culture method for lesser mealworm, Alphitobius diaperinus (Panzer), was developed to provide large numbers of adult lesser mealworms of approximately the same age for insecticide resistance testing. Culturing entailed allowing 100 adults to reproduce for 4 days in a wheat-based culture medium contained inside a plastic culture box, removing the adults from the medium, and then rearing their progeny to adulthood therein, in approximately 56 days at 32 degrees C and 55% RH. During their development, progeny were supplied water via apple slices at 0, 21 and 35 days, and a foam substrate in which to pupate, also at 35 days. During 2004-2005, adult lesser mealworms were collected from six broiler-house populations and then cultured with this method. Each population produced 4500 adults required to complete resistance testing with one insecticide within ten culture boxes, at an average of 798 adults per culture box.