Ji Gang Kim

Changes in microbial population and quality of microgreens treated with different sanitizers and packaging films

The effects of different sanitizers on the quality and microbial populations of ‘Tah Tasai’ Chinese cabbage (Brassica campestris var. narinosa) microgreens were evaluated. Samples were washed in tap water (TW), 100 mL·L−1 chlorinated water (Cl), 0.25% (w/v) each of citric and ascorbic acid mixed solution (CA + AS) as well as 0.5% (w/v) citric acid solution followed by 50% (v/v) ethanol spray (CA + E) and were packaged either in 35 μm polyethylene (PE) or polypropylene (PP) bag and stored at 5°C for up to 9 days. The decline of O2 partial pressure of the packaged headspace and hue angle values were similar in both films. However, the CO2 partial pressure of the packaged headspace and the electrical conductivity were substantially higher in PP packaged samples than that in PE. Off-odor scores were also higher in PP film packaged samples compared to that of PE. CA + E and CA + AS treatments showed lower off-odor scale in both films. Although, visual quality scores showed similar trends at the beginning of storage, CA + E and CA + AS treated samples exhibited better quality on day 7. Samples washed in Cl showed lower microbial count numbers on washing day. However, CA + E treatment exhibited either the lowest or equivalent count numbers in both total aerobic counts and coliforms count to that of Cl until the end of storage. Considering environmental safety, our results suggest that CA + E treatment could be a useful replacement for Cl for the washing of microgreens and PE film would provide more benefits than PP for packaging microgreens.

Physicochemical and microbial quality of stored green slender pepper treated with different washing solutions and packaging films

The effects of different washing solutions and packaging films on textural, biochemical and microbial quality of green slender peppers (Capsicum annuum L.) were evaluated. Fresh pepper samples were packaged either in 35 µm polypropylene or polyethylene bag without washing or after washing in tap water (TW), 100-ppm chlorine solution, 0.5% calcinated calcium solution followed by 25% ethanol rinsing (CC+E) and 1% citric acid solution followed by 50% ethanol spray (CA+E) and then stored at 10 ℃ for 4 weeks. Significant differences were found in gas composition between the two packaging films. Changes in skin puncture force, hue angle, soluble solid content, titratable acidity and pH were statistically insignificant. Chlorophyll a, chlorophyll b and total chlorophyll content declined significantly (P < 0.05) in all treatments during storage. Significant reduction (P < 0.05) in aerobic plate count was found in all washing treatments compared to unwashed sample except in TW. Yeast and mold count of chlorine and CC+E-treated samples were lower than other treatments. Samples of these two treatments also received marketable limit of visual quality scores until 4 weeks of storage in polypropylene film. Results suggest that CC+E could be a potential sanitizer and alternative to chlorine washing and polypropylene film would provide a little better advantage than polyethylene for green slender pepper.

Effects of Packaging on Shelf Life and Postharvest Qualities of Radish Roots during Storage at Low Temperature for an Extended Period

To investigate the effects of packaging on the quality aspects of radish, Korean radish roots (Raphanus sativus L. var. Kwandong) were stored at 0°C after different packaging treatments such as keeping in paper cartoon box (control), keeping in plastic crates (PC), packaging with micro perforated HDPE film in PC (HDPE + PC), curing followed by keeping in PC (Curing + PC), and curing followed by packaging with micro perforated HDPE film in PC (Curing + HDPE + PC). Weight losses of radish roots were remarkably lower ( values, whiteness index, total soluble solids, and flesh and skin firmness were better maintained in Curing + HDPE + PC treatment compared to other treatments. Lower color difference values were also found in this treatment. Both film packaged samples had lower scores of black spot, surface shrinkage, and fungal infection incidence which revealed significantly longer marketable periods. HDPE film packaged samples exhibited longer shelf life more than one and two months compared to control and unpacked samples, respectively. Results suggest that HDPE film packaging can extend postharvest life of radish while curing might have little but beneficial effects in maintaining the quality characteristics. To our knowledge, this is the first report on quality evaluation of Korean radish during an extended storage period simulating the Korean industrial practices.