In vitro digestibility, crystallinity, rheological, thermal, particle size and morphological characteristics of pinole, a traditional energy food obtained from toasted ground maize

Effects of different oleogelators on the structural properties and composition of iron walnut-oil oleogels

In this study, we compared the quality of iron walnut oil (IWO) oleogels prepared with different oleogelators, including γ-oryzanol/β-sitosterol (OZ-PS), γ-oryzanol/triglyceride (OZ-TC), monoglycerides (MGS), beeswax (BW), beeswax-monoglycerides (BW-MGS), and carnauba wax (CW). The physicochemical and component properties, rheological and textural parameters, macroscopic morphologies, and antioxidant capacities of the resulting oleogels were analyzed. In addition, their microscopic properties were analyzed using Fourier-transform infrared (FTIR), X-ray powder diffraction (XRD) spectroscopy, and polarized light microscopy (PLM). The results showed that the gel structures produced by different oleogelators did not change the fatty acid composition of IWO. In addition, the IWO oleogel prepared with OZ-PS had a more stable network structure, excellent hardness at 4℃ (1116.51 g), better antioxidant capacity (766.50 μmol TE/kg) and higher total phenolic content (14.98 mg/kg) than any other experimental IWO oleogels. Moreover, comprehensive ranking by principal component analysis of numerous characteristics showed that the OZ-PS oleogel (2.533) ranked first among the six oleogels studied. Therefore, the IWO oleogel prepared with OZ-PS is a promising product, and our results provide guidance for the preparation of IWO oleogels, such as to increase their applications in the food industry.

Changes in structural, digestive, and rheological properties of corn, potato, and pea starches as influenced by different ultrasonic treatments

Ultrasound was widely used in starch modification, whereas there was no review focusing on the effects of different ultrasonic treatments on A-, B- and C-type starches. In this study, the effects of ultrasonic power (UP, 100-600 W) and ultrasonic time (UT, 5-35 min) on structural, digestibility and rheology of corn starch (CS), potato starch (PtS), and pea starch (PS) were investigated. As a result, UP and UT decreased the apparent amylose content of CS and PS, while increased the apparent amylose content of PtS. UP and UT enhanced R1047/1022 values of CS, whereas those of PtS and PS were decreased. Moreover, UP and UT decreased the gelatinization enthalpy of CS, PtS and PS. In vitro digestion revealed that UP and UT decreased the resistant starch content of PtS and PS, but increased the resistant starch content of CS. Rheological tests indicated that UP and UT decreased the flow behavior index of CS, PtS and PS pastes, and caused an increase in storage modulus and loss modulus. Results revealed that ultrasonic treatment represented a promising technology to obtain CS, PtS and PS with tailored digestibility and rheology, which allowed the texture and glycemic response of starch-based products to be adjusted.

Determination of starch crystallinity with the Fourier-transform terahertz spectrometer

We measured the terahertz (THz) spectra of native, amorphous, and dried starches derived from corn and potato using the Fourier-transform (FT) system and compared these spectra to the X-ray diffraction (XRD) patterns. Both native corn and potato starches had seven absorption peaks in the terahertz regions, but five peaks were observed in the amorphous states. While spectral changes slightly occurred in corn starch even after drying, increase and decrease in the terahertz peak intensities were obtained in potato starch during drying. Similar changes in both starches during amorphization and drying were obtained in the X-ray diffraction patterns, and the correlations were found between terahertz peaks and the X-ray signals. Since the intensity of the peak at 9.0 THz was correlated with crystallinity obtained using an X-ray diffraction (r² = 0.98), our data indicate that the Fourier-transform terahertz spectrometer can be a new analytical device to measure the starch crystallinity.

Understanding the impact of Pulsed Electric Fields treatment on the thermal and pasting properties of raw and thermally processed oat flours

The aim of this research was to investigate the effect of Pulsed Electric Fields (PEF) treatments (electric field strengths 2 and 4.4 kV/cm combined with specific energy inputs between 48 and 484 kJ/kg) on the thermal and pasting properties of oat flours. Colour, β-glucan content, particle size distribution, morphological characteristics, starch short-range molecular order, protein secondary structure, thermal, and pasting properties of raw (dehulled and milled) and thermally processed (kilned at 115 °C for 30 min and steamed at 100-104 °C for 18 min under industrial process condition) oat flours under the influence of PEF treatment were evaluated. Results showed that PEF treatment, applied at any intensity, led to considerable changes in the structural properties especially when applied on raw oat flour. Both types of oat flour experienced an increase in particle size (up to four-fold), damage of starch granule morphology, and modifications in starch short-range molecular order and protein secondary structures as a result of PEF treatment. These physical changes observed after PEF treatment, particularly at increasing specific energy input, coincided with the thermal and pasting behaviour of PEF-treated oat flours, which include a decrease in gelatinisation enthalpy (up to 80%), increase in thermal transition temperatures (at least 3 °C), decrease in overall viscosity profile, and reduction in pasting temperature (up to 12 °C). Overall results suggested that PEF treatment improved majorly on starch-related functionality of oat, such as increased the pasting stability of raw and thermally processed oat flours and at the same time enhanced the retrogradation property (reduced syneresis and hardness) of raw oat flour, under lower temperature requirement without affecting pasting time. This research demonstrated the potential of PEF treatment in modifying the thermal and pasting properties of oat flour, thereby offering opportunities for novel products for food industry.

Viscoelastic and Textural Characteristics of Gels Obtained from Potato Starch Roasted under Several Temperature-Time Conditions

The influence of roasting conditions on the potato starch (PS) composition, solubility, crystallinity, gel-forming thermal profiles, and texture of the corresponding gels was studied. Thermorheological testing of roasted starches with (RPS) and without (RPSI) the soluble fraction was conducted on a stress-controlled rheometer. Texture profile analysis (TPA) was used to determine the RPS final gel texture. Solubility tests showed equivalent effects of starch roasting for samples treated at 190°C for 8 h (RPS190-8), 210°C for 6 h (RPS210-6), and 230°C for 4 h (RPS230-4). The apparent amylose content of RPS linearly increased with the decreasing degree of crystallinity. Elastic (G′) and viscous (G″) properties of RPS depended markedly on apparent amylose content and crystallinity. G′gel values of roasted starches linearly increased with the amylose content suggesting a promotion of the amylose breakdown with roasting temperature. Gels prepared with RPS roasted between 120 and 170°C exhibited intermediate strength and fully thermal reversible features. Roasting between 190 and 210°C favoured strong and fully thermal reversible gels. Although RPS230-4 gels exhibited similar strength to RPS190-8 and RPS210-4, no fully thermal reversible gels were obtained. The soluble fraction removal led to a drop the RPSI gels strength with increasing roasting temperature. No water syneresis was identified for RPS gels during one-week ageing, except for RPS230 gels. Relationships between textural parameters from TPA and viscoelastic gel properties determined by rheology were established.

Physicochemical, Thermal, and Sensory Properties of Blue Corn (Zea Mays L.)

The aim of this study was to investigate some physicochemical and sensory properties of blue corn cultivated in Turkey. The length and width of the cob with kernels, hectoliter, and 1000-kernel weight of blue corn were measured as 7.66, 2.02 mm, 84.40 kg/100 L, and 44.27 g, respectively. The gelatinization onset, peak, and end temperatures were measured as 61.12 °C, 64.35 °C, and 75.65 °C, respectively. The water activity, moisture content, total protein, lipid, and crude fiber contents of the blue corn sample were detected as 0.44, 9.39%, 13.13%, 4.30%, and 2.68%, respectively. Total starch and resistant starch contents of blue corn were determined as 63.94% and 8.89%, respectively. Also, total monomeric anthocyanin content and antioxidant capacity of blue corn were detected as 915.43 mg CGE/kg and 7.99 μmol TE/g, respectively. Additionally, the major fatty acids detected in blue corn samples were palmitic, stearic, oleic, and linoleic acids.

PRACTICAL APPLICATION

Blue corn can be utilized in the production of enjoyable and healthier snacks, such as popcorn and chips, because of its color and high phenolic, anthocyanin, and fiber contents.