Fresh “Maehyang” strawberry fruits were grown and harvested from commercial green- houses in Jinju, Gyeongsangnam-do, Korea. Strawberry fruits were harvested in the early morning and immediately precooled in storage room at 1˚C for 2 hour. Fruits of uniform medium size with red color on 70% of the fruit surface were used for this study. Postharvest treatment was 30% concentration of carbon dioxide gas with 3 hour and using strawberry modified atmosphere packaging film (Xtend, Stepac, Israel).

“Maehyang” samples treated with 30% concentration of CO₂ alone and combined CO₂ with MA packaging were stored for one day at 1˚C, transported for 10 days at 1˚C by vessel container, and distribution condition; cold storage for 3 days at 4˚C, retail market (10˚C - 15˚C) and room temperature.

Quality evaluations included weight loss, firmness, total soluble solid (TSS) and sensory analysis.

Weight loss was evaluated by measuring the weight of eight randomly chosen boxes. Fruits were weighed using a digital balance scale (HH320, OHAUS, NJ, USA) just before treatment in South Korea, again upon their arrival in Singapore and retail marketing duration.

All texture measurements were undertaken potable firmness testing machine (FHM-5, Takemura, Japan) and 10 individual fruit per treatment were selected for each of them.

Total soluble solids (TSS) were measured according to the AOAC procedures [9] . On each evaluation day, 5 fruit from each replicate was wrapped with 2 layer of cotton cloth and squeezed with a hand pressed juice maker. TSS of the resultant juice was measured in terms of brix using a refractometer (PAL-1, Atago Co. Ltd, Tokyo, Japan).

The sensory analysis of strawberry sample was carried out by expert panel. The member of the panel were trained to recognize and overall visual quality of strawberry sample prior to the test. These sensory qualities were evaluated by using 9-point scale (9 = excellent, 7 = good, 5 = moderate, 3 = poor, and 1 = unusable). A score of 6 was considered as the limit of marketability. To incidence of decay was analyzed by eye and then quantified as a percentage by counting the number of decayed fruits divided by the total number of fruits in a single plastic box, and multiplying by 100. There were 20 - 24 strawberries in each plastic box weighing approximately 280 g. Softening score of individual fruit in a box was carried out on 5-scale (0 = 0% surface softened, 1 = up to 10% surface softened, 2 = 10 to 25% surface softened, 3 = 25 to 50% surface softened, and 4 = >50% surface softened) [2] .

The experiment was conducted with three replications per treatment. Statistical analyses of the data were carried out using SAS software (SAS Institute, Cary, NC, USA). The level of significance was calculated from the F value of ANOVA. Mean comparison was achieved by Duncan’s multiple range test.

Weight loss during storage due to transpiration was observed for all treatments. Combination of CO₂ and MA treatments showed significantly lower values than the control and CO₂ treatment. Modified atmosphere such as box in bag, it maintained moisture and freshness. By Robinson et al., losses of 6% of the initial value of fresh weight of a soft fruit should be considered the limit for marketability [10] . In this study, after 14 days of storage, control had loss 2% and CO₂ treatment had loss 3% due to stress of gas injection in acrylic chamber. However treated with combination of CO₂ and MA was shown that loss of fresh weight was 1% in 14 days of storage at under 4˚C. Comparing all treatments, combination of CO₂ and MA treatments had a significant effect on weight loss, presenting the lowest values (Figure 1).

One of the main factors used to determine fruit quality and postharvest shelf life is the amount of loss of firmness during the storage of soft fruit such as strawberries [11] . By Manning [12] , fruit softening is attributed to the degradation of cell wall components, mainly pectin, due to the action of specific enzymes such as polygalacturonase. The firmness of strawberries increased as the 30% concentration of carbon dioxide treatment within 3 hour. After vessel export at 1˚C, firmness was maintained higher than control in all storage condition (Figure 2). Although increases in fruit firmness were reported in other studies by the application of high level of carbon dioxide [5] [6] , in addition to the firmness enhancement observed when strawberry fruit are held at low temperatures [13] . The firmness of strawberries after vessel export remained higher than harvest firmness values throughout the 15 day period of continuous cold storage at under 4˚C. By F.R. Harker et al., strawberries from all treatments softened rapidly and no residual effect of CO₂-enhanced firming was detectable within 3 days at 20˚C (data not shown) [6] . However, “Maehyang” strawberries treated with CO₂ and CO₂ + MA maintained firmness until 3 days at room temperature (over 26˚C), unlike that of

untreated control.

Total soluble solids are a critical factor for determining fruit quality and consumer acceptability. Sugars are the main soluble metabolites, and include glucose, fructose and sucrose comprising 99% of total sugar content [14] . The TSS of cv. “Maehyang” strawberries at harvest was 10.88˚ Brix and all treatments showed increases in the values during the storage time (Table 1). TSS was remained with low temperature storage, whereas TSS of “Maehyang” strawberries stored in retail market at 10˚C - 15˚C were shown 9.72˚ Brix at the end of marketing (after harvest 14 days).

Sensory quality is related to the characteristics of the food and how consumers perceive them [15] . With increasing storage time, deterioration starts with decay, fermentation and bruising [16] . Visual quality of “Maehyang” strawberries after vessel transportation was evaluated. Carbon dioxide alone and combination of CO₂ and MA treatment were effective in delaying dark red coloration on fruit surface.

Softening index of “Maehyang” strawberries was the highest in the control group at 11 days of storage (<4˚C) (Figure 3). After 15 days of storage (<4˚C), control showed higher score than those of CO₂ and combined CO₂ with MA treated strawberry. However, in low temperature storage under 4˚C, it restrained to occur softening on the surface of strawberry. Comparing all treatments, CO₂ and combination of CO₂ and MA treatments had a significant effect (p < 0.05) on softening index, presenting lower

0 means at harvest before treatment. 0’ means after treatment of CO₂ for 3 hr before storage. Data are means ± S.E.

values than control.

Overall score of “Maehyang” strawberries decreased gradually in storage time in all treatments at room temperature after vessel export (Figure 4). Although samples of different treatments received marketable scores until 12 days of storage (cold storage following 10 days transportation). After 2 days at room temperature after cold storage following 10 days transportation, strawberries lost marketability in all the treatment representing severely softening. Non-treated control showed lower score than those of CO₂ and CO₂ + MA treated strawberry.

Decay development is one of the main causes for postharvest losses of horticultural

produce. In particularly, strawberries are highly susceptible to microbial infection and have a short shelf-life caused by Botrytis cinerea [17] . Fruit decay was not shown by cold temperature storage (<4˚C) for up to 15 days after harvest. However, the decay rate was the highest in the control group at 3 days room temperature storage cold storage following 10 days transportation (Figure 4). High carbon dioxide levels may have inhibited decay by Nielsen and Leufven [18] . At the point of 2 days in room temperature, it occurred fungal decay on control and CO₂ + MA. And after 3 days in room temperature, all treatments were shown that fungal decay on surface. In summary, worth notice is that we did not detect any decay at all when strawberry were sent immediately after vessel export and retail marketing, but only after storage at room temperature (simulation in wholesale market) high levels of fungal decay were shown after 2 days of storage on control and CO₂ + MA, and after 3 days, all treatments were shown high percentage of fungal decay on fruit surface.