Influence of room-temperature storage-reheating cycles on nutritional properties of maize meal porridge (PAP) used in the vaal region, South Africa

South African maize meal porridge (pap) was analyzed for its nutritional properties after reheating by microwave following room-temperature storage for 12 and 24 h. In comparison with freshly prepared samples, reheated samples showed a higher resistant starch content with values of 44.2 ± 8.1 g/100 g and 39.8 ± 9.4 g/100 g when reheated after 12 and 24 h, respectively, compared with 31.4 ± 7.9 g/100 g for a fresh pap. A lower (P < 0.05) total protein content was recorded after the room storage-and-reheating cycle with values of 11.76 ± 2.4 g/100 g for fresh pap and 8.96 ± 1.57 and 7.56 ± 1.78 for pap reheated at 12 and 24 h, respectively. In vitro protein digestibility (IVPD) was also improved (P < 0.05). These results, especially the improvement of resistant starch content and the IVPD during room storage-and-reheating cycle of South African maize meal porridge, may open new perspectives to maize consumers both from the socioeconomical and nutritional point of view. PRACTICAL APPLICATIONS: Despite the safety benefit of the thermal process that is applied to extend the shelf life of foods, natural nutrients could be significantly lost, thus in principle a continuous cycle of storage and reheating of food should be avoided. This study posits that in addition to improving the safety of room-stored maize meal porridge; resistant starch (RS) improvement during the storage-reheating cycle offers unique health benefits, including intestinal/colonic health and glycemic management. RS is also " invisible" in foods as it does not affect taste and texture like other insoluble fiber sources often do.The increase of the in vitro protein digestibility by the heating process may also be advantageous for populations where the high prevalence of protein-energy malnutrition is largely caused by the poor nutritional quality of the diet. These results may be useful for decision makers, public health authorities and governments with regard to food safety and regulation for consumers.