Effect of blanching time and salt concentration on pectolytic enzymes, texture and acceptability of fermented green beans.

Effect of blanching time, salt concentration and fermentation on texture of green beans (var. Tuf) was determined. Beans were blanched at 90 degrees C for 1, 10 or 20 minutes and fermented with brine containing 3.08 and 4.6% salt (corresponding to 1.2 and 1.8% salt in the finished product). The beans were assessed for texture mechanically using Universal Testing Machine (Model 1011, Instron). Sensory evaluation was carried out to assess the taste, texture and overall acceptability of the products. Pectolytic enzyme (pectinestarase and exopolygalacturonase) activities were determined in fresh and fermented beans. Increase in blanching time improved the texture significantly. Significant (p<0.05) decreases in shearing energy of the beans were observed in the first two days of fermentation and, thereafter, there were no significant (p>0.05) changes except for samples blanched for one minute. Salt concentration showed a small but significant effect on texture only in samples blanched for one minute and this was probably due to activation by salt of residual pectolytic enzymes in the beans. Most acceptable beans were those blanched for 20 minutes and fermented with 1.2% salt brine.