Using repeated ingestion to determine the effect of sweetness, viscosity and oiliness on temporal perception of soymilk astringency

Astringency is a persistent sensation which increases upon repeated ingesti on. To evaluate the effect of viscosity, sucrose and oil on perception of a stringency during consumption of soymilk, a sequential sipping time-intensi ty (TI) procedure was utilized. For each soymilk, judges sipped the first o f four ingestions and initiated the continuous recording of astringency int ensity. Each sip was expectorated at 10 s after ingestion, and sipped 10 s after expectoration of the previous stimulus. After the fourth sample, judg es rated astringency for 30 s. Traditional TI parameters, as well as rate o f onset for each sip and increase in maximum intensity per sip were extract ed from the TI curves. Maximum astringency (IMAX) increased significantly w ith successive sips as did the astringency at the time of sipping. Time to IMAX decreased from sip 1 to 3, but was longer for sip 4, which may be an a rtifact of the rapid test pace. Although addition of 60 g l(-1) canola oil had no affect on astringency, adding 40 g l(-1) sucrose or increasing visco sity by 5 cp with CMC significantly lowered all astringency parameters. The reduction in astringency by CMC may result from restoration of salivary lu brication and in part by chelation or hydrogen bonding of CMC to the astrin gents reducing their ability to bind to salivary proteins. The reduction in astringency produced by sucrose is more probably due to a cognitive proces s. (C) 1999 Elsevier Science Ltd. All rights reserved.