Sompoch Noichinda

Changes in pectic substances and cell wall hydrolase enzymes of mangosteen (Garcinia mangostana) fruit during storage

Abstract Mangosteen (Garcinia mangostana) fruits at mature green stage with 5% red spotting were held at room temperature (31–35°C, 84 ± 2% relative humidity (RH)) and at the storage temperature of 13°C (90 ± 2% RH). Firmness, pectin content, and activities of pectin methylesterase and polygalacturonase in the pulp (aril) were monitored every 2 days. Pulp firmness rapidly decreased at room temperature from day 0 to day 4 after storage and slightly decreased thereafter, whereas pulp firmness slowly decreased at 13°C. Water soluble pectin content in pulp increased more rapidly at room temperature than at 13°C. Insoluble pectin content in pulp decreased throughout the storage time at both storage conditions. Both pectin methylesterase and polygalacturonase activities in pulp increased more rapidly at room temperature than at 13°C. Changes in water soluble pectin and cell wall hydrolase enzymes in relation to pulp softening of mangosteen fruits are discussed.

Postharvest Physiology and Quality Maintenance of Tropical Fruits

Tropical fruits are grown and developed in high temperature climatic zones, presenting a biodiversity of fruit cultivars varying in structure, characteristics and physiology. Their exotic appearances attract consumers around the world. Many fruits exhibit respiratory and ethylene production patterns associated with fruit maturation. Physiological changes of climacteric fruits depend on independent ripening of the pulp and rind. Practices during production, handling, and storage lead to postharvest disorders of the fruits. Most tropical fruits are sensitive to low-temperature storage with an optimum storage temperature of 13±1°C. Physiological disorders resulting from metabolic responses of the fruit to the storage environment decrease their marketable values. A practical protocol for delivering tropical fruits of good quality to the consumer is to harvest both climacteric and non-climacteric fruits at the proper maturity and apply the proper postharvest handling techniques such as artificial ripening to balance quality concerns with distribution requirements.

Assessment of volatile and non-volatile organic compounds in the liquid endosperm of young ‘Nam Hom’ coconut (Cocos nucifera L.) at two stages of maturity

SUMMARY Young coconut (Cocos nucifera L.) fruit collected 6–8 months after anthesis (MAA) contain a high volume of water [20% (w/w)] and can provide a refreshing drink. The present study investigated volatile organic compounds (VOCs), as aroma components, and physico-chemical changes in the liquid endosperm of young ‘Nam Hom’ coconut at two stages of maturity: the one-layer stage (6 MAA) and the two-layer stage (7.0–7.5 MAA) of the flesh. The liquid endosperm of coconut fruit becomes sweeter and more turbid late during maturation. Lauric acid (C12:0) and myristic acid (C14:0) were the main free fatty acids in the liquid endosperm of coconut. Short-chain fatty acid (C10–C12) concentrations increased slightly, and longer-chain fatty acid (C14–C18) concentrations declined when fruit matured from the one- to the two-layer stage of flesh. Solvent extractions showed a 1.4-fold increase in the total concentration of VOCs in the liquid endosperm during fruit development. This was related to a major increase in squalene and sterols, to 21.7% (w/w) of the total VOC and non-volatile organic compounds, whereas the concentrations of terpenes and esters remained stable. Although a series of alkanes existed in the liquid endosperm of coconut, the main aroma components were 2-methyl-1-butyl acetate and terpenes such as D-limonene, α-pinene, and 3-carene. We conclude that, when coconut fruit developed from the one- to the two-layered flesh stage, the liquid endosperm not only became sweeter and contained higher concentrations of aroma volatile and non-volatile components, but also became oily and less translucent.

Corrigendum to “Capillary Water in Pericarp Enhances Hypoxic Condition during On-Tree Fruit Maturation That Induces Lignification and Triggers Translucent Flesh Disorder in Mangosteen (Garcinia mangostana L.)”

Translucent flesh of mangosteen normally occurs during fruit ripening. Rainfall, after water stress, enhanced on-tree mature green fruit to develop translucent flesh disorder more frequently. Thus, this research pursued the effect of applied water on translucent flesh disorder development. The on-tree mature green stage fruits were selected and wrapped with 3 layers of fabric sheet. After that, water was continuously dropped (flow rate of 0.6 ml/min) on the wrapped sheet for 0, 1, and 2 days before picking. The results showed that duration time of water applying enhanced the increasing of water absorption significantly in peel. All of water-treated fruits ripened within 2-3 days after harvest and obviously had high lignin in secondary cell wall. It was hypothesized that lignification played an important role in hypoxia defense mechanism since the Na2CO3-SP fractionation extracted from alcohol insoluble residue (AIR) of translucent flesh aril was higher than those of normal aril. This Na2CO3-SP reinforced the strength of cell wall complexity as well as displaying the translucency character. Hence, we concluded that the capillary water (took place in intercellular air space of fruit pericarp) induced hypoxia tolerance mechanism that triggered translucent flesh disorder in mangosteen aril.

Direct androgenesis in anther culture of butterfly pea related to flower development

Androgenesis is a biotechnological pathway of in vitro gametic embryogenesis with the potential leading to haploid plant production from male reproductive organ. Butterfly pea (Clitoria ternatea L.) is a versatile leguminous plant with the floral shape resembling a butterfly at full bloom. Based on the varying lengths of flower as well as petals and sepals, 5 stages of flower development were delineated. When anthers from flowers of these various stages were cultured on basal Murashige and Skoog medium supplemented with 3 mg/l 2,4-D and 60 or 80 g/l sucrose, it was found that anther-derived embryos (11.67 and 3.3% in the presence of 6 and 8% sucrose, respectively) were obtained only from stage 2 flowers. Light microscopic observation also revealed that the microspores of anthers isolated from flowers at stage 2 was uninucleate. This suggested that anther or microspore stage of butterfly pea played a very important role in direct androgenesis and 8% sucrose in the medium was detrimental to this process.

The utility of electrospun nanofibre mats for in vitro germination of Artabotrys hexapetalus pollen

This study investigates the influence of electrospun fibre mats on in vitro pollen germination of Artabotrys hexapetalus (L.f.) Bhandari (synonym: A. odoratissimus R. Brown). There was no difference in the size of the pollen from two closely related stages of flower development, namely the yellow florets and yellowish orange florets. On agarbased medium supplemented with 20% sucrose, about 50% of the pollen from the yellowish orange florets germinated but only 25% of those from the yellow florets did. More pollen from the yellowish orange florets germinated in liquid medium than on agar-gelled medium but pollen tube elongation was greater in agar-gelled medium. Electrospinning of synthetic polymer solutions of polyvinylidene fluoride (PVDF) or polylactic acid (PLA) was used to generate mats composed of nonwoven (randomly oriented) nanofibres as well as those composed of a mixture of nonwoven and aligned (PVDF4 and PLA4) nanofibres. Compared with liquid, agar medium, and other types of nanofibre mats, PVDF4 was found to be the best physical support substrate for germination of the pollen from the yellowish orange florets (70%) and tube growth (about 400% increase over that in liquid medium). Pollen germination was largely inhibited on all four types of 18 μm thick nanofibre mats but not on the 8 μm thick ones.