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Nejayote is a nixtamalization waste by-product, and for this reason, in this study, filtration cakes as well as filtrate nejayote were evaluated to select the filter medium and also to establish the operation conditions. The different media used as filters at constant pressure filtrations were polyester–cotton canvas, paper, and nylon. The filtrations showed that polyester–cotton canvas presents lower specific resistance of the cake at all pressure levels and dosages. Calcium content was less in filter medium nylon at pressure 98.10 kPa and dosage 1:0.25 nejayote/diatomaceous earth. Regarding particle diameter, the nylon and paper filter media have the highest quality filtering at pressure of 63.77 kPa and dosage 1:0.25 nejayote/diatomaceous earth. Therefore, the filtration depends not only on the particle diameter of the solids, dosage and nejayote cake morphology, but that the filter media is also important in the selection of the operation conditions. [ABSTRACT FROM PUBLISHER]

Nowadays, in Mexico and Latin America, calcium content in the diet is a very important issue. This fact is critical since research studies have shown a relationship between consumption of dietary calcium and chronic degenerative diseases. Deficiencies of calcium in Mexican population involve the search for alternative foods that lead to an increase in the daily calcium intake. In this context, the traditional nixtamalization process is a good option for food processing in order to increase calcium content in foodstuffs. This work focused on the development of an effective methodology to establish the relationships among the processing variables in the production of nixtamalized corn flours by the traditional method. A full compound factorial design was used to determine the effect of some independent variables, involved in the nixtamalization, on the response variables such as (a) Ca+2content in corn flours, (b) particle size distribution (homogeneity), and (c) average energy consumption during grinding. [ABSTRACT FROM PUBLISHER]

The aim this work was to establish the best conditions to increase the soluble dietary fiber (SDF), evaluate the effect of extrusion on the SDF, and insoluble dietary fiber (IDF), in a snack obtained by extrusion, that serve as a source of calcium and DF, using mixtures of oat–corn pericarp. The corn pericarp was obtained from byproduct of nixtamalization process which contains water, calcium hydroxide, soluble solids, and pericarp. The studied parameters were temperature (120–140°C), moisture (200–400 g/kg), and corn pericarp (200–400 g/kg); the responses were expansion ratio, SDF, IDF, and water absorption index (WAI). TheR2were > 0.85 for all factors. The best conditions were temperature (133°C), moisture (230 g/kg), and corn pericarp (300 g/kg), with responses of 93.1 g/kg increase in SDF, 60 g/kg decrease of IDF, expansion of 1.26, WAI of 4.12 g sediment/g dry solid, and calcium content 4350 mg/kg. [ABSTRACT FROM PUBLISHER]

Abstract: The microstructural changes in the maize pericarp during the critical lime-cooking step of a traditional nixtamalization process are reported. Scanning Electron Microscopy at low vacuum (SEM-LV) images and Energy Dispersive Spectrometry (EDS) were used to study the evolution of the pericarp transformation during lime-cooking and the CaCO3 formation on the pericarp. Moisture content in cooked maize kernels and calcium content in the pericarp were used as physicochemical criteria in order to establish the end of the cooking step. For the first time, the cooking step was analyzed in situ by using a differential photoacoustic cell (DPC), in order to associate photoacoustic amplitude signals of nixtamalized pericarp with its structural modifications. X-ray diffraction patterns of nixtamalized pericarp showed an increase in the peak intensity of the crystalline fraction compared with the native pericarp. These results were supported by SEM images and amplitude signals obtained through the use of the photoacoustic technique. [Copyright &y& Elsevier]

Abstract: In the present work the results of the mechanism of calcium uptake in nixtamalized corn kernel were studied. The results showed that at a critical time, the calcium uptake in the pericarp suffers a drastic change; this fact cannot be associated only to the diffusive mechanism. The SEM analysis of processed corn kernels, taken at 1h of steeping time illustrates a calcium cluster formation. It means that for short steeping times the calcium uptake in the total kernel is governed by an accumulation process in the most external layers of the pericarp and the diffusion process is not relevant. The apparition of micro-holes for critical time in dependence on the temperature indicates that another mechanism is contributing to the calcium uptake. These holes can pass thought the whole pericarp or form an interconnected lattice to develop a percolation path. The holes formations allow the entrance of water and calcium directly to the outermost layers of the endosperm and now the accumulation of calcium is not the predominant mechanism. It could be implied that, at this critical time the percolation of water and calcium thought these holes is the main mechanism to calcium uptake in the corn kernel and the diffusion process is not relevant. [Copyright &y& Elsevier]

The objective of this work was to prepare solid lipid nanoparticles (SLNs) based on the hot lipid dispersion method using a rotor–stator device in order to obtain a submicronic system and evaluate the effect of SLN-xanthan gum coatings on the guava shelf life. Candeuba® wax was used as a component of SLN. The coating was formulated with xanthan gum (4g/L) and polyethylene glycol (5g/L) in order to form a continuous film retaining the SLN. The SLN concentrations were varied from 60 to 80g/L and were compared with the control and xanthan gum. These were evaluated (n=3) every third day. The film-forming dispersion was applied by dipping the guavas and storing them under refrigeration at 10°C and 85% RH for 30days. Every 5days guava samples were transferred to room temperature (25°C) in order to assess the effect of maturation on the changes in weight loss, chemical quality, texture and color. It was established that Candeuba® wax as a SLN maintained the quality of guavas, and that the SLN concentration in the film formation depends on the characteristics of the fruits. The best results were obtained with SLN concentrations of 60 and 65g/L since at these concentrations, guavas showed the lowest range of weight loss and preserved the best quality compared to the fruits processed at concentrations above 70g/L. In addition high contents of SLN cause physiological damage and also delay the maturation which can be observed by the greenness color without changes. [ABSTRACT FROM AUTHOR]