Violet-red discolouration of canned Palmyra palm during processing

Abstract

The objectives of the research were to investigate the causes of the violet-red discolouration during processing of canned Palmyra palm and to identify preventive methods without the use of chemical additives. Palmyra palm flesh with (13-21 %) /without some peel left on was tested for the source of violet-red discolouration during blanching. It was found that blanching in distilled water had no effect on discolouration when blanching conditions were at 75, 85, and 95°C for 7 min but the violet-red discolouration occurred only when tap water was used for blanching at 95°C for 7 min. Moreover, the addition of bicarbonate (NaHCO 3 ) in distilled water to imitate higher alkalinity of tap water during blanching could contribute to the violet-red discolouration. Thus the observed cut off alkalinity of the blanching water wherein not to expect any discolouration was found to be about 100 ppm. After sterilization, there was no violet-red discolouration from Palmyra palm flesh without any peel left on even though it had a preceding treatment of blanching in highly alkaline tap water.

Shelf-life extension of tender endosperm of Palmyra palm (Borassus flabellifer) through retort processing

“…This may be due to violet-red discolouration of PTFE due to the presence of specks of whitish skin layer that affects the color value a*. Leucoanthocyanidin in peels leads to pink discolouration due to oxidation reactions (Chamchong et al, 2016). When the pH of the sugar solution was lowered, red anthocyanidin was acquired from the whitish peel of the tender endosperm.…”