The demand for nixtamalized products has broadened the industrialization of maize. The nejayote is a product of the alkaline cooking of grain, and unfortunately contributes to environmental deterioration after being dumped into the public sewer system. There is evidence that adequate treatment of this byproduct not only reduces pollution, but it is also a source of compounds with high added value with potential for technological applications. The objective of this review was to provide an overview of the main methodologies and technological developments which have been implemented to explore the physico-chemical properties of nejayote and to assign a treatment or an application to it. With the work performed it was possible to detect that the recovery of materials with high added value (polyphenols, carbohydrates, sugars, gums and calcium components) can be used in various areas such as the food. pharmaceutical and biotechnological sectors. In addition, it was identified that the obtaining of these components can be carried out through the coupling of various bioprocesses (fermentation, filtration, centrifugation and decantation).

The hardness of grains can help determine the optimal harvest time and their postharvest handling. This study was conducted with the objective of developing an experimental methodology to indirectly determine the hardness of quinoa (Chenopodium quinoa Willd.) seed. Five quinoa samples (Blanca Canadá, BT, RT, Ontifor and NT) were evaluated in terms of moisture (%), hectoliter weight (kg∙hL-1) and hardness (breaking resistance). In order to determine the last-mentioned variable, 200 g of seed were sieved in No. 10, 14 and 18 meshes with a retention tray underneath; this was done in order to homogenize the size. Quinoa retained on each sieve was weighed. From mesh 14, which was the one with the highest retention (80 %), 30 g were ground for 2 s and sieved in No. 14, 18, 20, 24 and 30 meshes, with a retention tray underneath. The fractions obtained were weighed and the retention percentages of each sieve were obtained. To classify the hardness of the grain, a hedonic scale was developed. RT, BT and Ontifor were categorized as slightly hard, and Blanca Canadá and NT as slightly soft. The Ontifor sample showed the highest moisture and hectoliter weight, while NT had the lowest moisture percentage and the softest grain. The methodology used to determine hardness is easy to use both in the field and industry and may be useful in other small grains.

Compost application is a common practice in agricultural soils, usually with manure or excreta. Its use provides organic matter and nutrients, and improves the aeration, moisture retention and physicochemical composition of the soil. The aim of this study was to evaluate in a non-natural soil the effect of adding compost, produced with green waste, in terms of its organic matter content and water holding capacity. The compost used was made at the National Polytechnic Institute (IPN) Compost Plant. The soil, obtained from green areas at IPN’s Professional Interdisciplinary Biotechnology Unit, is mainly composed of natural soil, gravel and sand. Six treatments were used: three with soil mixed with compost, one with soil with chemical fertilizer and two controls (negative: 100 % soil; positive: 100 % compost). The parameters analyzed in the soil were: organic matter content (OM), moisture content (M), field capacity (FC), pore space (PS %), water holding capacity (WHC) and permanent wilting point (PWP) in corn and bean plants. In all treatments with compost, a significant increase in OM, PS %, M %, FC, PWP and WHC was observed, with the treatment with 20 % compost being the one that presented the best results. It was concluded that adding compost produced with green waste increased OM content and helped to improve some soil characteristics.