Microfluidic paper-based analytical device for measurement of pH using as sensor red cabbage anthocyanins and gum arabic.

The objective of this study was to develop and validate a novel microfluidic paper-based analytical device (µPADpH) for determining the pH levels in foods. Anthocyanins from red cabbage aqueous extract (RCAE) were used as its analytical sensor. Whatman No. 1 filter paper was the most suitable for the device due to its porosity and fiber organization, which allows for maximum color intensity and minimal color heterogeneity of the RCAE in the detection zone of the µPADpH. To ensure the color stability of the RCAE for commercial use of the µPADpH, gum arabic was added. The geometric design of the µPADpH, including the channel length and separation zone diameter, was systematically optimized using colored food. The validation showed that the µPADpH did not differ from the pH meter when analyzing natural foods. However, certain additives in processed foods were found to increase the pH values.

High methoxyl pectin grafted onto gallic acid by one- and two-pot redox-pair procedures.

The aim of this research was to graft gallic acid (GA) onto high methoxyl pectin (HMP) through the redox-pair of ascorbic acid (Aa) and hydrogen peroxide (H2O2) with one- and two-pot procedures. The effectiveness of the both procedures and the chemical, physical and antioxidant properties of the obtained HMP-GA were evaluated. HMP-GAone-pot (23.3 ± 0.21 mg GA Equivalent (GAE)/g) and HMP-GAtwo-pot (32.3 ± 0.52 mg GAE/g) were best obtained at H2O2/Aa molar ratio-HMP/GA weight ratio of 9.0-0.5 and 16.0-0.5, respectively. The UV-Vis and FT-IR spectra and along with their derivative and thermal gravimetric analyses, revealed differences between HMP-GAone-pot and HMP-GAtwo-pot. The latter exhibited a greater antioxidant capacity than the former in single electron transfer (ET), hydrogen atom transfer (HAT), and ET-HAT mixed assays. The chemical differences can be attributed to side reactions that may have interfered with the grafting reaction. Consequently, HMP-GA, possessing unique antioxidant and prebiotic properties, can be synthesized through redox-pair procedures.

Physicochemical and functional properties of isolated starch and their correlation with flour from the Andean Peruvian quinoa varieties.

Quinoa has been recognized as a complete food due to its balanced nutritional composition. Quinoa flour is used as an ingredient to improve the nutritional and functional characteristics of cereal-based foods. The physicochemical and functional (thermal and pasting) properties of flours and isolated starches of three Andean Peruvian quinoa varieties (Blanca de Hualhuas, BH; Rosada de Huancayo, RHY and Pasankalla, PK) were studied and the correlation among them properties were evaluated in order to explore their possible uses as a food ingredient. Proximal chemical composition of flour and isolated starches from quinoa varieties showed differences. Isolated starches from quinoa varieties showed a XRD Type A crystallinity patterns with polygonal shapes, small size, higher crystallinity degree and lower amylose content (<15%). The thermal (gelatinization temperatures and enthalpies) and pasting (temperature and time of gelatinization and viscosities) properties of flours and isolated starches showed differences and the principal component analysis demonstrated that those properties are significantly correlated to the starch and fat content. Based on the differences found among physicochemical and functional properties, isolated starch and flour of BH, RHY and PK quinoa varieties have potential as food ingredient for several cereal-based products.

A green analytical assay for the quantitation of the total saponins in quinoa (Chenopodium quinoa Willd.) based on macro lens-coupled smartphone.

The aim of this study was to develop and validate a microtiter macro lens-coupled smartphone (MCS) assay for the quantitation of the total saponins in quinoa based on foam measurement. The 96-well micro plate with a black bottom and an inclination angle = 12.102° of macro lens-coupled smartphone allows to acquire images with a high resolution. The foam stability, a critical aspect for the MCS assay, was significantly improved by the inclusion of a chelating agent (EDTA 50 mmol L-1) and bovine serum albumin (0.5 mg mL-1). The MCS assay was linear within the range of 9.039-180.773 × 10-4 mg mL-1 of saponin (R2 = 0.9929), using the integrated density/area as a foam measurement (Y) and the logarithm of saponin concentration (X) (Y = 372.1 + 104.2LogX). The MCS assay was 50-folds more sensitive than afrosimetric assay -AA- with LOD = 3.168 × 10-4 mg mL-1 and LOQ = 4.784 × 10-4 mg mL-1. MCS assay was more reproducible (relative standard deviation (RSD) = 0.632-9.646%) than AA (RSD = 3.44-44.04%). The correlation analysis, Bland-Altman analysis and Passing-Bablok regression showed good agreement between total saponin content in quinoa as measured by the MCS assay and AA. Based on the green analytical procedure index, MCS assay can be considered as a green procedure.

Microencapsulated betacyanin from colored organic quinoa (Chenopodium quinoa Willd.): optimization, physicochemical characterization and accelerated storage stability.

BACKGROUND: Betalains are presently gaining popularity as pigments for use as natural colorants and/or bioactive compounds in functional foods. Quinoa (Chenopodium quinoa Willd.) has been recognized as an extremely nutritious grain and has recently been found to be a novel and good betalain source. Microencapsulation has been studied as a protected-delivery procedure to stabilize betalains. There are no studies about microencapsulation of betacyanins extracted from quinoa using spray-drying technology. RESULTS: Optimal microencapsulation was obtained at a drying temperature of 165 °C, a rotameter air flow rate of 47 mm (940 L h-1 ) and 10% w/w maltodextrin, which produced good encapsulation yield (58.1%) and efficiency (100%). Optimized maltodextrin-betacyanin microcapsules (diameter 4.4 µm) have low moisture (1.64 ± 0.08%) and water activity (0.127 ± 0.006), a betacyanin content of 0.1995 ± 0.0017 g kg-1 and saponin content <0.080 mg kg-1 . The oxygen consumption rate by betacyanin was -4.373 × 10-5 bar min-1 at 80 °C and -6.67 × 10-5 bar min-1 at 90 °C, which was accompanied by fading of the color. CONCLUSION: Microencapsulated betacyanin was optimized by response surface methodology, and its stability was measured under accelerated conditions by oxygen consumption. Microencapsulations contain betacyanin and low saponin concentration, which might confer unique health-promoting properties. © 2018 Society of Chemical Industry.

Physical features, phenolic compounds, betalains and total antioxidant capacity of coloured quinoa seeds (Chenopodium quinoa Willd.) from Peruvian Altiplano.

Physical features, bioactive compounds and total antioxidant capacity (TAC) of coloured quinoa varieties (Chenopodium quinoa Willd.) from Peruvian Altiplano were studied. Quinoa seeds did not show a pure red colour, but a mixture which corresponded to different fractal colour values (51.0-71.8), and they varied from small to large size. Regarding bioactive compounds, total phenolic (1.23-3.24mg gallic acid equivalents/g) and flavonol contents (0.47-2.55mg quercetin equivalents/g) were highly correlated (r=0.910). Betalains content (0.15-6.10mg/100g) was correlated with L colour parameter (r=-0.569), total phenolics (r=0.703) and flavonols content (r=0.718). Ratio of betaxanthins to betacyanins (0.0-1.41) was negatively correlated with L value (r=-0.744). Whereas, high TAC values (119.8-335.9mmol Trolox equivalents/kg) were negatively correlated with L value (r=-0.779), but positively with betalains (r=0.730), as well as with free (r=0.639), bound (r=0.558) and total phenolic compounds (r=0.676). Unexploited coloured quinoa seeds are proposed as a valuable natural source of phenolics and betalains with high antioxidant capacity.