Panida Boonyaritthongchai

Effects of fresh Aloe vera gel coating on browning alleviation of fresh cut wax apple (Syzygium samarangenese) fruit cv. Taaptimjaan.

The effect of natural coating by using fresh Aloe vera (A. vera) gel alleviating browning of fresh-cut wax apple fruits cv. Taaptimjaan was investigated. The fresh-cut fruits were dipped in fresh A. vera gel at various concentrations of 0, 25, 75 or 100xa0% (v/v) for 2xa0min at 4xa0±xa01xa0°C for 6xa0days. Lightness (L*), whiteness index (WI), browning index (BI), total color difference (ΔE*), sensorial quality attributes, total phenolic (TP) content, antioxidant activity and polyphenol oxidase (PPO) and peroxidase (POD) activities were determined. During storage, L* and WI of the fresh-cut fruits surface decreased whilst their BI and ΔE* increased. A. vera coating maintained the L* and WI and delayed the increase in BI and ΔE*, especially at 75xa0% A. vera dip. The fresh-cut fruits dipped in 75xa0% A. vera had the lowest browning score, the highest acceptance score and delayed the increase in TP content and PPO activity. However POD activity was induced by A. vera coating. Antioxidant activity had no effect on browning incidence of the fresh-cut fruits. Consequently, A. vera gel coating could maintain quality and retarded browning of fresh-cut wax apple fruits during storage.

Assessment of three green papaya (Carica papaya Linn.) cultivars (‘Krang’, ‘Kaek Noul’, and ‘Kaek Dum’) for use as shredded fruit

Summary Immature Carica papaya fruit of three cultivars (‘Krang’, ‘Kaek Noul’, and ‘Kaek Dum’) known to be suitable for processing as papaya shreds were harvested 60 – 70 d after anthesis. ‘Krang’ had the largest fruit among the three cultivars. The mean fruit firmness values for intact ‘Krang’, ‘Kaek Noul’, and ‘Kaek Dum’ papaya fruit were 95.2 N, 99.4 N, and 109.7 N, respectively. The mean rates of respiration and ethylene production in intact fruit were not significantly different among the three cultivars. The flesh of ‘Krang’ fruit had the highest L* and hue angle (hº) values (68.1 and 112.8, respectively), and the flesh of ‘Kaek Dum’ was more yellow in colour than the flesh of the other two cultivars, expressed as a b* value of 8.9. During storage at 10ºC and 85 – 90% relative humidity, shreds of ‘Kaek Dum’ fruit flesh retained the highest average shear force values, followed by ‘Kaek Noul’ and ‘Krang’. Shreds of ‘Krang’ fruit showed a relatively higher loss of fresh weight than ‘Kaek Dum’ or ‘Kaek Noul’ (3.7 – 5.8%, 2.4 – 3.2%, and 1.1 – 2.2%, respectively), and this loss appeared to correlate with the microstructure of the parenchyma cells. The cellular morphology of shredded fruit was observed using a scanning electron microscope (SEM). The SEM revealed that parenchyma cells in ‘Krang’ were larger than those in ‘Kaek Noul’ and ‘Kaek Dum’. On day–6, fruit flesh shreds of ‘Kaek Noul’ and ‘Kaek Dum’ scored higher than those of ‘Krang’ in a trained, ten-person panel test on a nine-point hedonic scale for overall acceptance, with values of 5.0, 4.3, and 3.6, respectively. ‘Kaek Noul’ and ‘Kaek Dum’ papaya fruit were therefore better suited for processing into shreds and had a longer storage-life of 6 d. Although, initially, ‘Krang’ fruit had the best appearance and a high L* value after peeling, these features were lost during storage at 10ºC and reduced the storage–life to only 4 d.

Postharvest quality maintenance and bioactive compounds enhancement in ‘Taaptimjaan’ wax apple during short-term storage by salicylic acid immersion

Physicochemical quality and bioactive compounds of ‘Taaptipjaan’ wax apple (Syzygium samarangenese) that were immersed in 0, 0.5 and 1.0xa0mM salicylic acid (SA) for 30xa0min and then stored at 12u2009±u20091xa0°C for 9xa0days were investigated. SA had no effect on the colour of fruit skin, total soluble solids, total acidity, total sugars, ascorbic acid (AsA) and anthocyanin contents but could help maintaining the firmness of the fruit. Antioxidant activity, total phenols, total flavonoids and antioxidant enzymes activities such as peroxidase and catalase were enhanced by SA. The SA immersion at the concentration of 0.5xa0mM effectively maintained firmness and visual appearance without causing any shrinkage on the fruit top and skin pitting and enhanced the bioactive compounds greater than 1.0xa0mM SA immersion. The evidences suggest that 0.5xa0mM SA immersion is an effective approach of maintaining quality and enhancing bioactive compounds including the activities of antioxidant enzymes in the fruit during short-term storage.

The effect of fluidzed bed drying temperature and packaging condition on retarding degradation of purple waxy rice during storage

The objective of this research was to retard degradation in color, anthocyanin content, total phenolic content, antioxidant activity and free fatty acid content resulting in undesirable rancidity in purple waxy rice by applying post harvested drying technique and packaging. Paddy with initial moisture content of 25%w.b. was dried by a batch fluidized bed dryer with various temperatures of 100, 130 and 150oC till the moisture reduced to 18.0%w.b. The dried paddy was then dehulled and packed, 50 g/bag, in a polypropylene woven bag, laminate bag and laminated bag within and without an oxygen absorber at ambient temperature for 90 days storage. After drying process, the results revealed that the proper temperature for drying paddy was at 130oC which did not affect the postharvested quality of sample. However, the dried rice should be kept in the laminated bag containing an oxygen absorber for it was the most effective retarding rice quality degradation.

Effects of methyl jasmonate on physicochemical qualities and internal browning of ‘queen’ pineapple fruit during cold storage

The effects of methyl jasmonate (MeJA) as a protectant against chilling injury on physicochemical qualities of ‘Trad-see-thong’ pineapple (‘Queen’ group) fruit was investigated. The pineapple fruit were immersed in 1 mM MeJA for 5 min and then stored at 10 ± 1°C for 20 days. MeJA had no effect on respiratory rate and pulp colour, but suppressed ethylene production during cold storage. Weight loss, ion leakage (IL), internal browning (IB), and loss of pulp firmness were inhibited by MeJA. The MeJA treatment also suppressed the reduction of lightness (L*) and yellowness (b*) and the increase of total phenols (TP) that commonly occurs during cold storage, and increased the polyphenol oxidase (PPO) activity of pulp adjacent to the core (PAC) tissue. Certain bioactive compounds, such as ascorbic acid (AsA) and superoxide dismutase (SOD) in PAC tissues were enhanced by MeJA. No significant difference in peroxidase (POD) activity in both pulp and PAC tissues were detected between the treated and control fruits. These results suggest that immersion in MeJA is an effective means to maintain quality, alleviate IB symptoms, and enhance certain bioactive compounds in ‘Queen’ pineapple fruit cv. Trad-see-thong during cold storage.

Physicochemical changes of ‘Phulae’ pineapple fruit treated with short-term anoxia during ambient storage

The effects of short-term anoxia exposure for 16h on physicochemical changes of Phulae pineapple fruit stored at ambient temperature (25±2°C) were investigated. The respiratory rate of the fruit was induced by the anoxia treatment. However, it retarded the increase in moisture loss and maintained both flesh and pulp colour by inhibiting polyphenol oxidase (PPO) activity of the both tissues. The anoxia exposure delayed the increase in total sugar content and enhanced total ascorbic acid content during storage. The half-cut pineapple fruit showed that the anoxia exposure completely inhibited internal transparency of the flesh tissue adjacent to core during the storage. In conclusion, the short-term anoxia exposure for 16h maintained postharvest quality, retarded physiological disorder and enhanced nutritional values of the pineapple fruit stored at ambient temperature (25±2°C).

Physiological and physico-chemical changes in green papaya (Carica papaya L. ‘Kaek Noul’) shreds taken from the outer or inner mesocarp

ABSTRACT This study compared physiological and physico-chemical changes in shreds of green papaya (Carica papaya L. ‘Kaek Noul’), taken from inner and outer mesocarp tissues, during storage at 7ºC for up to 8 d. Reductions in the flesh firmness of shreds, microstructure, colouration, dry matter content (DMC), and fresh weight (FW) loss, and in the rates of respiration, ethylene production, and enzyme activities were measured. The rapid loss of firmness of green papaya ‘Kaek Noul’ shreds taken from the inner mesocarp was attributed to the larger and more loosely arranged cells of the inner mesocarp compared to the smaller and compact cells of the outer mesocarp. Shreds taken from the outer mesocarp had a higher DMC [6.21–6.77% (w/w)] than those from the inner mesocarp [5.83–6.34% (w/w)] during storage at 7ºC. FW loss was higher for shreds from the inner mesocarp than from the outer mesocarp (0.89–1.12% vs. 0.39–1.00%, respectively). Colour values (h°) were lower at the end of storage for shreds from the inner mesocarp than shreds from the outer mesocarp (104.38° and 111.94°, respectively). Moreover, scanning electron micrographs of shreds from inner mesocarp and outer mesocarp tissues showed that the slower loss of firmness in shreds from the outer mesocarp could be attributed to having smaller and more compact cells, as well as to lower ethylene production by the outer mesocarp. However, this was not related to cellulase activity. This study indicated why processors prefer to use shreds from the outer mesocarp of green papaya.