ACTIVE MODIFIED ATMOSPHERE PACKAGING USING ZP AGELESS TO CONTROL CUT SURFACE BROWNING OF PEELED ONION

Packed peeled onion is gaining popularity in Malaysian supermarkets and hypermarkets. The product can be introduced for food retail stores and food services such as restaurants, hotels, food institutions and food industries. The problems of peeled onion during storage include growth of roots, sprouts, fungal infection, surface drying and browning, unpleasant and strong smell and discolouration. This study was carried out to investigate the combined effect of water and oxygen absorber on the quality and shelf life of peeled onion in bulk packaging. Peeled onion packed in corrugated fiber board (CFB) boxes lined with low density polyethylene (LDPE, 0.04 mm thickness) containing water absorber (Supasorb^TM) alone served as the control, and in combination with oxygen absorber (ZP Ageless 100^TM) as treatment. Packed peeled onions were stored at 2°C and quality evaluations were carried out at weekly intervals for 8 weeks. It was shown that the oxygen absorber increased discolouration, texture loss and CO₂ production of peeled onion during storage. The oxygen absorber caused an increase in ethylene production at the end of storage (week 7). The total titratable acidity (TTA) was reduced by O₂ absorber after 3-4 weeks of storage. There were no significant differences on the effect of O₂ absorber on O₂ concentration in packages, pH, lightness (L), total soluble solids (TSS) and microbial counts. The oxygen absorber in modified atmosphere packages of the peeled onion has the advantages of delaying rooting and sprouting, reduction of yellowing on the cut surface and maintaining the ascorbic acid content during 8 weeks storage at 2°C.