Interaction of Monoglycerides with Starches

In bread‐making practice, the emulsifier glycerolmonostearate (GMS) is commonly used as an improving agent, though the mechanism of its action is not fully elucidated. Most of earlier studies have been made on starches in molecular solution. The present investigation deals with interactions of the emulsifier (in fact a mixture of glycerolmonostearate and ‐palmitate) and starches in suspension, at temperatures ranging from 30–90°C. The quantity of monoglycerides bound by the starch was determined by sampling the reaction vessel at time intervals and re‐extracting the monoglycerides that were left free in the suspension. Quantitative determination was achieved with the aid of gas‐chromatography. It was found that at 30 °C, part of the monoglycerides is irreversibly bound by the starch granules; during gelatinization, the quantity of emulsifier bound shows a considerable increase to reach, at 90 °C, an equilibrium at a higher level. Probably, the monoglyceride molecules penetrate into the swollen starch granules to form an insoluble complex with amylose. Various starches included in the study showed essentially similar behaviour, but were quantitatively different in their capacity to bind monoglyceride. At 30 °C, wheat starch binds a greater part of added monoglycerides than does cassava starch; at 90 °C the situation is the reverse.