KERNEL CHARACTERIZATION AND STARCH MORPHOLOGY OF FIVE VARIETIES OF PERUVIAN ANDEAN MAIZE

Peruvian Andean maize (PAM), because its adaptation to different crop environments, has different features to commercial corn, nevertheless, there no studies focusing on characteristics of agro-industrial interest for the development of new products. In this sense, this study aimed to evaluate the characteristics of kernels and the starch granule morphology of the five main varieties of PAM: Chullpi, Piscorunto, Giant Cuzco, Sacsa and Purple. For this purpose, physicochemical and pasting properties of samples were determined according to the official methods. Starch granules morphology was carried out by Scanning electron microscopy (SEM), focusing on two areas of endosperm (sub-aleurone and central) at magnifications: 1000x, 2000x and 6500x, dimensions and distribution of starch granules were measured using software Image J. Results showed differences between PAM kernels properties. Physically, Giant Cuzco and Sacsa varieties had the highest 1000-kernel weight with 1340.63 and 1197.58 g, respectively; while, Purple maize had the best hectolitre-weight (61.56 kg/100L) and the most intense coloration. For centesimal composition, Chullpi, Purple, and Sacsa varieties presented the higher protein, ether extract, and dietary fiber contents with 8.52%, 5.11%, and 20.29%, respectively. SEM showed that sub-aleurone starch is composed of small and polyhedral granules compacted in matrices, whereas central starch granules are bigger and spherical. Between PAM varieties, Sacsa presented a bimodal distribution of granules Type-A (>10 µm) and Type-B (<10 µm), with smooth and porous surfaces, while the rest had a monomodal distribution of smooth Type-A granules. The differences observed can explain the variability of PAM pasting properties as pasting temperature between 69 to 71°C, peak viscosity of 4500 cP, and seatback of 1500 cP, which resulted in gels with greater skin strength (~1N) and elasticity (~5 mm). The results suggest that PAM has characteristics that could be useful for optimizing food industrial processes and achieving final products with desired properties.