Browning in Freeze-Dried Fruits, Effect of Moisture Content of Freeze-Dried Peaches and Bananas on Changes during Storage Related to Oxidative and Carbonyl-Amine Browning

Abstract

In both freeze-dried peaches and bananas during long-term storage in air at 28°C , little change was observed at storage moisture levels below 10% in total phenolic substances, free amino nitrogen, reducing sugar, and sucrose content. In both freeze-dried peaches and bananas, peroxidase activity decreased rapidly at all moisture levels during storage at 28°C. In both freeze-dried peaches and bananas, polyphenol oxidase activity was most stable at the lowest moisture levels and became relatively unstable at 8% moisture and above. Treatment with sulfur dioxide protected ascorbic acid, but had only a limited effect on browning. Loss of ascorbic acid was minimum at minimum moisture levels in both products. After 190 days' storage, the Amadori compounds, "fructose-y-amino butyric acid" and "fructose-valine," were found in untreated, freeze-dried bananas at moisture levels above 0.70% and in sulfur-dioxide-treated samples above 3.75% moisture. A level of 5% moisture or lower is effective in preventing brown discoloration of peaches and bananas stored at 28°C. for at least 6 months.

Storage Stability of Dehydrated Food Evaluation of Literature Data

“…Samples without in-package desiccation lost up to 75% ascorbic acid within the same period of time. Similar results were reported by Karel and Nickerson (1964) and Draudt and Huang (1966), whose results suggested that moisture content should be reduced to the lowest possible level for prevention of ascorbic acid losses. On the other hand, extremely low levels of moisture result in a reduced nutritional quality in products such as avocados, tomatoes and some vegetables.…”

Nutritional effects of food processing

“…In dried fruits, where the main reaction is between carbonyl and amino groups (Harper & Tappel, 1957), sulphur dioxide protects the vitamin C but has only a limited effect on the development of the brown colour (Draudt & Huang, 1966).…”

Perubahan Karakteristik Bahan Pangan pada Keripik Buah dengan Metode Freeze Drying (Review)

“…Pemberian sulfur dioksida pada penanganan buah dinilai dapat menurunkan oksidasi asam askorbat pada buah. Selain itu, juga dapat mencegah pencoklatan pada buah [25].…”