Foxtail millet, as a leading variety in arid and semi-arid areas of Asia and Africa, can provide broad potential benefits to human health. However, its digestion properties have not been reported. So in this study, the in vitro starch digestibilities and in vivo glycemic indices (GI) of foxtail millet and pure millet products were investigated. The results showed that starch digestibility of the foxtail millet flour is obviously lower than that of wheat flour. However, deproteinization and heating significantly increased its rapidly digestible starch and decreased its slowly digestible starch and resistant starch. The GIs of pure millet products were in the following order: millet porridge (93.6 ± 11.3) > millet steamed bread (89.6 ± 8.8) > No. 1 millet pancake (75.0% millet flour and 25.0% extrusion flour, 83.0 ± 9.6) > No. 2 millet pancake (without extrusion flour, 76.2 ± 10.7) > cooked millet (64.4 ± 8.5). They were significantly positively correlated with the rapidly digestible starch (r = 0.959), degree of gelatinization (r = 0.967) and estimated glycemic index (r = 0.988). Both in vitro and in vivo tests suggested that boiling, steaming and extrusion enhanced the formation of digestible starch and subsequently increased the GI values. Additionally, the No. 1 millet pancake and cooked millet had a relatively gentle stimulation on β-cell. Therefore, foxtail millet, especially the cooked millet, may serve as a potential source of nutraceutical and functional food that could delay the development of type 2 diabetes.

Changes in the composition of soybean oil during deep-fat frying with wheat dough (WD) and chicken breast meat (CBM) were comparatively investigated using gas chromatography–mass spectrometry and Fourier transform infrared spectroscopy (FTIR). The amounts of saturated fatty acids (FAs) and short-chain FAs were increased. The amount of unsaturated FAs was decreased as the processing time increased. An increase in the amount of tetradecanoic acid and 9-cis-hexadecanoic acid was observed during the CBM frying only. The FTIR spectrum of frying oil was analyzed by extracting the entire information as the area ratios based on vibration absorptions of the specific functional groups. Changes in content of functional groups, namely cis C=C, trans C=C, C=O, C–O, O–H, and C–H, were studied by the FTIR-based method. Based on the changes in the content of FAs and functional groups, soybean oil fried with CBM degraded more quickly than that fried with WD. Moreover, good linear correlations between the change in contents of functional groups and the mass percentages of FAs were also observed. The FTIR-based method could be used in real time to monitor the quality of frying oil during the deep-fat frying.

The thermal degradation and corresponding decomposition products of fresh and heat-treated soybean oil were investigated by synchronous thermal analyzer combined with Fourier transform infrared spectrometry and quadrupole mass spectrometry (STA–FTIR–QMS). Two longtime heat-treated soybean oil samples were aforehand prepared by consistently heating the fresh soybean oil for 50 and 100 h, respectively. N2 and simulative air (N2/O2 = 4:1, volume) were used as the thermal reaction gas atmosphere. The results showed that one stage of mass loss appeared in analysis of the all oil samples under N2 atmosphere condition and longtime heat pre-treatment had no effect on the thermal behavior of the soybean oil under N2 atmosphere condition. However, four stages occurred in analysis of both untreated and heat-treated oil samples under the simulative air atmosphere condition. Longtime heat pre-treatment influenced the thermal behavior of the soybean oil in certain extent, which was reflected in the different mass loss values of the four stages. According to the infrared absorption profiles and MS spectra of the released compounds in vapor phase, H2O, CO, CO2, hydrocarbons (such as CH4), and hydroxyl, carbonyl, and carboxyl-contained compounds have been confirmed. Therefore, STA–FTIR–QMS can be suggested as a promising technique for investigating of thermal degradation and monitoring the decomposition products of the evolving substances in edible oils.

The application of Fourier Transform Infrared (FTIR) Spectroscopy to authenticate edible vegetable oils (corn, peanut, rapeseed and soybean oil) adulterated with used frying oil was introduced in this paper. The FTIR spectrum of oil was divided into 22 regions which corresponded to the constituents and molecular structures of vegetable oils. Samples of calibration set were classified into four categories for corn and peanut oils and five categories for rapeseed and soybean oils by cluster analysis. Qualitative analysis of validation set was obtained by discriminant analysis. Area ratio between absorption band 19 and 20 and wavenumber shift of band 19 were treated by linear regression for quantitative analysis. For four adulteration types, LODs of area ratio were 6.6%, 7.2%, 5.5%, 3.6% and wavenumber shift were 8.1%, 9.0%, 6.9%, 5.6%, respectively. The proposed methodology is a useful tool to authenticate the edible vegetable oils adulterated with used frying oil.Highlights► The application of FTIR to detect used frying oil. ► FTIR spectrum of oil was divided into 22 regions. ► Calibration and validation set of samples combined with chemometrics. ► Typical area ratio and wavenumber shift were used as predictors.

Deep-fat frying at 180 °C or above is one of the most common food processing methods used for preparing of human kind foods worldwide. However, a serial of complex reactions such as oxidation, hydrolysis, isomerization, and polymerization take place during the deep-fat frying course and influence quality attributes of the final product such as flavor, texture, shelf life and nutrient composition. The influence of these reactions results from a number of their products including volatile compounds, hydrolysis products, oxidized triacylglycerol monomers, cyclic compounds, trans configuration compounds, polymers, sterol derivatives, nitrogen- and sulphur-containing heterocyclic compounds, acrylamide, etc. which are present in both frying oil and the fried food. In addition, these reactions are interacted and influenced by various impact factors such as frying oil type, frying conditions (time, temperature, fryer, etc.) and fried material type. Based on the published literatures, three main organic chemical reaction mechanisms namely hemolytic, heterolytic and concerted reaction were identified and supposed to elucidate the complex chemical alterations during deep-fat frying. However, well understanding the mechanisms of these reactions and their products under different conditions helps to control the deep-fat frying processing; therefore, producing healthy fried foods. By means of comprehensively consulting the papers which previously studied on the chemical changes occurred during deep-fat frying process, the major reaction products and corresponding chemical alterations were reviewed in this work.Highlights► A series of complex alterations occur and form many products during deep-fat frying. ► These products can be classified according to their similar characteristics. ► Chemical reactions were discussed based on their corresponding products. ► Homolytic, heterolytic and concerted reaction were summarized and proposed. ► It is full of benefits to well know the chemical reaction during deep-fat frying.

Rice starch–water suspension (20%) were subjected to high hydrostatic pressure (HHP) treatment at 120, 240, 360, 480, and 600 MPa for 30 min. Polarizing light microscope, scanning electron microscopy (SEM), rapid visco analyzer (RVA), differential scanning calorimeter (DSC), and X-ray diffraction were used to investigate the physicochemical and structural changes of starch. Microscopy studies showed that the treatment of starch with HHP under 600 MPa for 30 min resulted in a complete loss of birefringence and a gel-like appearance. The treatment of starch suspension with HHP at 600 MPa resulted in a significant increase in swelling power and solubility at low temperature (50–60 °C), but opposite trends were found at high temperature (70–90 °C). The DSC analysis showed a decrease in gelatinization temperatures and gelatinization enthalpy with increase of pressure levels. RVA viscograms of starches exhibited an increase in peak, trough, and final viscosities, peak time, and pasting temperature but decrease of breakdown, setback viscosities, and pasting temperature when pressure was increased. X-ray diffraction studies showed that the HHP treatment converted rice starch that displayed the A-type X-ray patterns to the B-type-like pattern. These results showed that the treatment of rice starch in 20% starch/water suspension at a pressure of 600 MPa for 30 min led to a complete gelatinization of starch granules.

Starch samples from ten mung bean cultivars grown in china were isolated, and their morphology, physicochemical, thermal, and pasting properties were evaluated. The objectives of the study were to investigate the starch properties and processing characteristics of different mung bean varieties, and to establish the basic foundation of improving the functionality of mung beans and their starch grown in the region. The mung bean starches showed the kidney-shaped, elliptical, small spherical and dome-shaped granules, and the starches granule size varied between 5 and 40 μm. Total starch content, amylose content, solubility, and swelling power ranged from 54.73% to 57.99%, 40.44% to 41.82%, 13.72% to 17.67%, and 17.27% to 20.55%, respectively. The pasting properties were determined using a rapid visco analyzer, and various mung bean starches exhibited different pasting profiles. Different starches differed in transition temperatures (To, Tp, and Tc), gelatinization temperature range (ΔTr), and enthalpy of gelatinization (ΔH) according to differential scanning calorimeter analysis. Hydration coefficient, degree of gelatinization, and hardness of mung bean varieties ranged from 51.97% to 84.46%, 62.99% to 95.11%, and 26.07 N to 112.11 N, respectively. This study indicated that starches separated from different mung bean cultivars possess different physicochemical characteristics, and various mung beans cultivars showed diverse processing properties.

Properties and qualities of vermicelli made from two different techniques of processing starches were studied in this paper. Vermicelli made from sour liquid starch had more significant mesh structure than vermicelli made from centrifugation. TCL(total cooking loss) value of vermicelli made from sour liquid starch was significantly lower than that from centrifugation starch. Amylose content of starch and TCL of vermicelli, degradation rate and TCL of vermicelli all had significance negative correlation. Amylose content had significance positive correlation with the degradation rate of vermicelli. The swelling index and TCL had no significance correlation.