Physicochemical changes in Amaranthus spp grains, flour, isolated starch, and nanocrystals during germination and malting

Amaranth is a pseudocereal that contains between 50 and 60% starch, gluten-free protein, and essential amino acids. This study investigates the physicochemical changes in Amaranthus spp. grains, flour, isolated starch and nanocrystals during germination and malting. The moisture content increased from 8.9% to 41% over 2 h of soaking. The percentage of germination increased rapidly, reaching 96% after 60 h, a remarkable advantage over other cereals. The nutrient composition varied, including protein synthesis and lipid degradation. Lipid concentration decreased during malting, except for soaking, which increased by 62%. Scanning electron microscopy shows that germination does not cause morphological changes on the outer surface of the grains, while transmission electron microscopy indicates the presence of isolated nanocrystals with orthorhombic crystal structure confirmed by X-ray diffraction. The viscosity profile shows a decrease in peak viscosity. Therefore, amaranth is a potential pseudocereal that can be used as an additive in the production of fermented beverages.

Comparative Analysis of the Chemical Composition and Physicochemical Properties of the Mucilage Extracted from Fresh and Dehydrated Opuntia ficus indica Cladodes

The development of sustainable extraction methods to obtain natural products constitutes a challenge for the food industry. The aim of this work was to compare yield, separation efficiency, chemical composition, and physicochemical properties of the mucilage extracted from fresh cladodes (FNM) and mucilage extracted from dehydrated cladodes (DNM) of O. ficus indica. Suspensions of fresh and dehydrated cladodes (4% w/w) were prepared for mucilage extraction by using a mechanical separation process. Subsequently, the separated mucilage was precipitated with ethyl alcohol (1:2 v/v) then, yield and separation efficiency were determined. The mucilage was characterized by measuring Z potential, viscosity, color, and texture attributes. Additionally, chemical proximate analysis, scanning electron microscopy, and thermogravimetric analysis (TGA) were conducted. No significant differences (p < 0.05) were detected in the yield and separation efficiencies between samples. Nevertheless, the dehydration process of cladodes prior to mucilage extraction increased protein, ashes, nitrogen free extract, and calcium content. The viscosity was higher in DNM than in FNM. The TGA revealed a different thermal behavior between samples. In addition, the DNM showed lower L (darkness/lightness), cohesiveness, adhesiveness, and springiness values than those of FNM. These results support that differences found between the chemical and physicochemical properties of DNM and those of FNM will determine the applications of the mucilage obtained from the O. ficus indica cladodes in the food, pharmaceutical, and cosmetic industries.

Physicochemical characterization of Amaranth starch insulated by mechanical separations

This work focused on the physicochemical properties of isolated Amaranth starch. Inductively coupled plasma (ICP) showed that amaranth is low-lipid calcium and magnesium source for the human diet. Scanning Electron Microscopy showed that isolated granules are in the range of sub and micro size. DSC starch thermogram showed a gelatinization temperature of 67.9 °C and an enthalpy of 10. 6 J/g suggesting the presence of an ordered crystalline structures. High-resolution X-ray diffraction showed the isolated starch contents nanocrystals with an orthorhombic crystalline structure whose pattern was indexed. The pasting profile showed that this kind of starch has an end cold viscosity as a custard, making it useful for infantile formulations. It does not present dynamic viscosity and would not be a problem when swallowed. A very important finding in this work was that the orthorhombic nanocrystals, after solvation during gelatinization, do not contribute to the apparent viscosity development.

Calcium Bioavailability in the Soluble and Insoluble Fibers Extracted from Opuntia ficus indica at Different Maturity Stages in Growing Rats

Childhood and adolescence are crucial stages of life for bone health. Therefore, an adequate calcium intake and a healthy life style constitute the main strategies to prevent the risk of osteoporosis-related fractures during adulthood. It has been demonstrated that inclusion of indigestible carbohydrates in foods can help improve calcium absorption in growing stages. The objective of this study was to evaluate the effect of supplementation of soluble and insoluble fibers extracted from O. ficus indica cladodes on calcium bioavailability. Male Wistar rats 4-week old were fed diets added with soluble and insoluble fibers extracted from O. ficus indica cladodes at early and late maturity stages, as the only source of calcium. The mineral content, bone mineral density (BMD), physical, microstructural, and biomechanical properties of rat femurs were determined. The bones of rats fed with diets containing a soluble fiber extracted from O. ficus indica at early and late maturity stages exhibited better bone properties (resistance to fracture, microarchitecture, and calcium content) than control rats and rats fed with an insoluble fiber from O. ficusindica cladodes at both maturity stages. As expected, based on these results, the BMD values were higher in adolescent and pubertal rats fed with a diet containing the O. ficus indica soluble fiber. These results demonstrate that the soluble fiber from O. ficus indica cladodes is indeed a valuable source of bioavailable calcium, which contributes to improve physical, densitometric, biomechanical, and microstructural properties of bone in growing rats.

Calcium Bioavailability of Opuntia ficus-indica Cladodes in an Ovariectomized Rat Model of Postmenopausal Bone Loss

Osteoporosis is a disease of the skeletal system characterized by low bone mass and bone weakening, which increase the risk of fracture. This disease is associated with menopause because hypoestrogenism induces the maturation and activation of osteoclasts. In addition, a low dietary intake of calcium leads to low bone mineral density and postmenopausal osteoporosis. The objectives of this work were to determine calcium bioavailability of Opuntia ficus-indica cladodes at a late maturity stage and to assess its contribution in improving bone health in an ovariectomized rat model. Two-month-old Wistar female rats (n = 35) were used and distributed in seven experimental groups: (i) control group (Crtl), (ii) sham group (SH), (iii) ovariectomized group (OVX), (iv) ovariectomized group supplemented with calcium citrate (CCa), (v) ovariectomized group supplemented with O. ficus-indica powder (NI), (vi) ovariectomized group supplemented with soluble fiber from O. ficus-indica (FS) and (vii) ovariectomized group supplemented with insoluble fiber from O. ficus-indica (FI). Our results showed that calcium in the soluble fiber of O. ficus-indica is bioavailable and contributes to improve the physical, densitometric, biomechanical and microstructural properties of bones in ovariectomized rats. These findings indicated that O. ficus-indica cladodes at a late maturity stage represent a good source of bioavailable calcium and consumption of these cladodes might be beneficial for the prevention of osteoporosis and other bone diseases.

Physicochemical Properties and Resistant Starch Content of Corn Tortilla Flours Refrigerated at Different Storage Times

The tortilla is a foodstuff that has a short shelf-life, causing great losses to the industry. The objective of this work was to evaluate, for the first time, the physicochemical properties and resistant starch (RS) content of flours. These were obtained from nixtamalized corn tortillas made with traditional and industrial (commercial) methods, stored at 4 °C for 7, 15, and 30 days. The flours were characterized by measuring particle size distribution, color, water absorption index (WAI), water solubility index (WSI), viscosity, calcium, and RS content. Additionally, chemical proximate analysis, scanning electron microscopy (SEM), and thermal analysis were conducted. Storage at 4 °C increased the friability of tortillas and shifted the particle size distribution toward a greater content of coarse particles in corn tortilla flours. The commercial corn tortilla flours showed higher WAI and WSI values than the traditional corn tortilla flours. On the other hand, the traditional corn tortilla flours exhibited higher RS content values than commercial corn tortilla flours as well as peak viscosity. X-ray diffractograms revealed the presence of amylose-lipid complexes (RS5) in experimental samples. The thermograms evidenced three endotherms corresponding to corn starch gelatinization and melting of type I and type II amylose-lipid complexes.

Characterization of crystalline structures in Opuntia ficus-indica

This research studies the crystalline compounds present in nopal (Opuntia ficus-indica) cladodes. The identification of the crystalline structures was performed using X-ray diffraction, scanning electron microscopy, mass spectrometry, and Fourier transform infrared spectroscopy. The crystalline structures identified were calcium carbonate (calcite) [CaCO3], calcium-magnesium bicarbonate [CaMg(CO3)2], magnesium oxide [MgO], calcium oxalate monohydrate [Ca(C2O4)•(H2O)], potassium peroxydiphosphate [K4P2O8] and potassium chloride [KCl]. The SEM images indicate that calcite crystals grow to dipyramidal, octahedral-like, prismatic, and flower-like structures; meanwhile, calcium-magnesium bicarbonate structures show rhombohedral exfoliation and calcium oxalate monohydrate is present in a drusenoid morphology. These calcium carbonate compounds have a great importance for humans because their bioavailability. This is the first report about the identification and structural analysis of calcium carbonate and calcium-magnesium bicarbonate in nopal cladodes, as well as the presence of magnesium oxide, potassium peroxydiphosphate and potassium chloride in these plants. The significance of the study of the inorganic components of these cactus plants is related with the increasing interest in the potential use of Opuntia as a raw material of products for the food, pharmaceutical, and cosmetic industries.

Effects of drying process on the physicochemical properties of nopal cladodes at different maturity stages

Chemical proximate analysis was done in order to determine the changes of nutritional characteristics of nopal powders from three different maturity stages 50, 100, and 150 days and obtained by three different drying processes: freeze dried, forced air oven, and tunnel. Results indicate that nopal powder obtained by the process of freeze dried retains higher contents of protein, soluble fiber, and fat than the other two processes. Also, freeze dried process had less effect on color hue variable. No changes were observed in insoluble fiber content, chroma and lightness with the three different drying processes. Furthermore, the soluble fibers decreased with the age of nopal while insoluble fibers and ash content shows an opposite trend. In addition, the luminosity and hue values did not show differences among the maturity stages studied. The high content of dietary fibers of nopal pad powder could to be an interesting source of these important components for human diets and also could be used in food, cosmetics and pharmaceutical industry.