The use of various surface treatments to prolong storage life of guavas at 10°C was examined. LDPE shrinkwrap was most effective in reducing weight loss and maintaining the firmness of guava (most likely indicating its effectiveness in alleviating water stress), followed by clingwrap packaging and 200 g litre-'palm oil emulsion coating. The skin colour of guava was most effectively preserved by LDPE packaging, sucrose-ester and 200 g litre-' palm oil emulsion dips. Paraffin treatment caused the skin to turn brown after 2 weeks storage. The ascorbic acid content was highest in control followed by clingwrapped guava. Clingwrapped guava also received the highest organoleptic scores followed by shrinkwrapping and 200 g litre-' palm oil treated guava.

Dehydrated pickled/candied guava and pineapples pretreated with 0.24 g kg-' cysteine hydrochloride (cys-HC1) had increased ascorbic acid retention and reduced colour change during storage. Dehydrated pineapples pretreated with cys-HC1 had two to three times the ascorbic acid content of control or metabisulphite-treated products. The rate of ascorbic acid loss for all products stored at room temperature were similar, showing that cys-HC1 was only protective towards ascorbic acid during the preparation and dehydration process. Candied dehydrated guava showed less colour change and higher ascorbic acid retention (about 57 O h ) than pickled guava (ascorbic acid retention about 30 %). Cys-HCI was quite effective in reducing browning of candied pineapples but not pickled pineapples. Sensory evaluation showed that candied guava pretreated with 0.24 g kg-' cys-HC1 was generally preferred over the other dehydrated guava products. Cys-HCI-treated candied pineapples had the best flavour compared with all other dehydrated pineapple products. Cys-HC1 appeared to favour conversion of glucose to fructose during storage of dehydrated pineapples.

No abstract