Endosperms of fenugreek and carob which have been leached following their isolation exhibit increased activity of endo-β-mannanase, part of which is released into the surrounding incubation medium. This activity was suppressed by the addition to the endosperms of abscisic acid or endosperm/seed coat leachate. The leachate from carob inhibited the increase of endo-β-mannanase activity in fenugreek and that from fenugreek inhibited enzyme activity in carob but more weakly; neither of these leachates inhibited the production of α-amylase in wheat endosperm. Polyethylene glycol-induced stress on non-leached endosperms inhibited endo-β-mannanase production, but not when the stress was applied following endosperm leaching. However, the stress did reduce the amount of enzyme released into the surrounding incubation medium. Several isoenzymes of mannanase could be detected on isoelectric focusing activity gels in the endosperms of both fenugreek and carob, but their pis differed between the two species. When activity was suppressed by ABA or leachate, all pl forms declined equally.

We have recently shown that a polyphenol-rich insoluble dietary fibre preparation from carob pulp (Ceratonia siliqua L; carob fibre) decreased postprandial acylated ghrelin, TAG and NEFA during an acute liquid meal challenge test. However, delayed effects of carob fibre consumption are unknown. Therefore, a randomized controlled crossover study in nineteen healthy volunteers consuming foods with or without 50 g carob fibre was conducted. On the subsequent day (day 2), glucose, TAG, total and acylated ghrelin as well as insulin, NEFA and leptin were assessed at baseline and at timed intervals for 300 min after ingestion of standardized bread. Consumption of carob fibre-enriched foods did not affect fasting concentrations of glucose, TAG, total ghrelin, NEFA, insulin and leptin. Fasting acylated ghrelin was increased on the day subsequent to carob fibre consumption compared with control (P = 0·046). After consumption of the standard bread on day 2, glucose response (P = 0·029) was increased, and TAG (P = 0·033) and NEFA (P < 0·001) responses were decreased compared with control. Postprandial responses of total and acylated ghrelin, insulin and leptin on day 2 were unaffected by carob fibre consumption the previous day. In conclusion, an increase in total and acylated plasma ghrelin accompanied by enhanced lipid metabolism after carob fibre consumption suggests higher lipid utilization and suppressed lipolysis on the day subsequent to carob fibre consumption. However, elevated glucose levels after carob fibre consumption need to be addressed in future studies.

Dietary fibre consumption is associated with improved glucose homeostasis. In contrast, dietary polyphenols have been suggested to exert both beneficial and detrimental effects on glucose and insulin metabolism. Recently, we reported that a polyphenol-rich insoluble dietary fibre preparation from carob pulp (carob fibre) resulted in lower postprandial acylated ghrelin levels after a liquid meal challenge test compared with a control meal without supplementation. The effects may, however, differ when a different food matrix is used. Thus, we investigated the effects of carob fibre on glucose, insulin and ghrelin responses in healthy humans in combination with a glucose load. In a randomized single-blind cross-over study involving twenty healthy subjects (aged 22–62 years), plasma glucose, total and acylated ghrelin, and serum insulin were repeatedly assessed before and after the ingestion of 200 ml water with 50 g glucose and 0, 5, 10 or 20 g carob fibre over a period of 180 min. The intake of 5 and 10 g carob fibre increased the plasma glucose by 47 % and 64 % (P < 0·001), and serum insulin by 19·9 and 24·8 % (P < 0·001), compared with the control. Plasma acylated ghrelin concentrations did not change significantly after the consumption of carob-enriched glucose solution. Total ghrelin decreased only after 10 g carob fibre (P < 0·001) compared with control. In conclusion, we showed that polyphenol-rich carob fibre, administered within a water–glucose solution, increases postprandial glucose and insulin responses, suggesting a deterioration in glycaemic control.