|Physicochemical, functional and digestion characteristics of thermally treated starches under acidic/alkaline conditions|
J. DE LA ROSA MILLÁN (1), S. Serna Saldivar (1), J. Orona Padilla (1), V. Flores Moreno (1) (1) Instituto Tecnológico y de Estudios Superiores de Monterrey, Monterrey, Other, Mexico.
In this study we explore the combination of thermal treatments like annealing (ANN) and heat moisture treatment (HMT), under acidic/alkaline conditions on starches with different granular characteristics (rice, maize and potato) in a pilot scale plant with the aim to increase its nutraceutical potential. For this, ANN treatment consisted on starch dispersions (30% solids content), that where incubated at 50°C, at pH 7.0, 2.0, and 10.0 for 24 h. While the HMT starches were prepared at 70% solids content and incubated at 120°C, pH’s were reached with either 2M HCl or 2M NaOH. After the time, both starches were neutralized (pH 7.0), air dried, grinded until pass 100 US mesh, and its proximal composition in terms of moisture, protein, ash and lipids were calculated, as well as water absorption index (WAI), water solubility index (WSI), oil absorption index (OAI). Additionally, the impact of the processing conditions on its digestion characteristics as the amounts of rapidly, slowly and resistant starch (RDS, SDS and RS) in gelatinized starch gels was estimated. We found that the proximate composition of the starches was not affected, WAI and WSI were higher on rice starch with ANN under acidic conditions compared with its native counterpart (4.3 g/g and 40% vs 2.5 g/g and 17%). The HMT treated starches showed the opposite trend in these characteristics. The OAI of native potato starch exhibits the lowest value (1.5 g/g), while ANN maize starch under acidic conditions retained the higher amount of oil (3.6 g/g). The highest SDS values were found on maize starch with ANN under acidic conditions (51.41%), the highest RS amount (57.53%) was found on native potato starch (pH 7.0). The outcome of this study can offer direction on the use of the analyzed starches in different food application, in order to be used as food ingredients without the introduction of chemical reagents.