Tailoring the physicochemical properties of starch: impact of integrated ultrasonic and ethanol pretreatment on the oil uptake of infrared fried ginkgo seeds.

BACKGROUND: The structural changes of starch would have a more crucial impact on oil absorption and quality changes in starch-rich fruits and vegetables during frying process with enhanced heat transfer (such as infrared frying). In the present study, the influence of integrated ultrasonic and ethanol (US + ethanol) pretreatment on oil uptake in infrared fried (IF) ginkgo seeds was evaluated regarding modifications in the physicochemical properties of starch. The pretreatment was performed with ultrasonic (40 kHz, 300 W) and ethanol osmotic (95%, v/v) treatment individually or integrated for 40 min. RESULTS: The mass transfer in the pretreatment was facilitated by combined ultrasound and ethanol. The swelling power, solubility, and gelatinization degree of starch was significantly increased. Low-frequency-NMR curves and images revealed that the bound water fraction in ginkgo seeds was increased and the water distribution was homogenized. The results of Fourier transform-infrared spectrum and differential scanning calorimeter revealed that the crystalline regions of starch were reduced and the thermal enthalpy was decreased after US + ethanol pretreatment. The total, surface and structural oil content in IF ginkgo seeds with US + ethanol pretreatment was reduced by 29.10%, 34.52% and 29.73%, respectively. The US + ethanol pretreatment led to a thinner crust layer with increased porosity and smaller-sized pores in the IF ginkgo seeds as observed by stereo microscopy and scanning electron microscopy. CONCLUSION: The changes in structural and physicochemical properties of starch by combined ultrasound and ethanol affect the crust ratio and pore characteristics in fried high-starch fruits and vegetables, thereby reducing oil absorption. © 2024 Society of Chemical Industry.

Facile Fabrication of Anthocyanin-Nanocellulose Hydrogel Indicator Label for Intelligent Evaluation of Minced Pork Freshness.

In order to develop a reliable and rapid method for meat freshness detection, nanocellulose (TOCNF) prepared via the TEMPO (2,2,6,6-tetramethylpiperidine oxidation) oxidation method was used as raw material to prepare hydrogels using Zn2+ coordination and binding. Physicochemical properties such as water absorption and porosity were analyzed. It was further used to select suitable hydrogels for the preparation of indication labels after anthocyanin adsorption, and it was applied in the freshness detection of fresh minced pork. Five percent TOCNF (w/w) aqueous solution was homogenized by high shear for 4 min, and 20% (w/w) zinc chloride solution was added to it, so that the concentration of zinc ions could reach 0.25 mol/L. After standing for 24 h, the hydrogel was obtained with good water absorption and a porous three-dimensional network structure. The activation energies of volatile base nitrogen (TVBN) and anthocyanin indicating label color changes were 59.231 kJ/mol and 69.453 kJ/mol, respectively. The difference between the two is within 25 kJ/mol, so the prepared indicator label can accurately visualize the shelf life of fresh pork.

Reduction of oil uptake in vacuum fried Pleurotus eryngii chips via ultrasound assisted pretreatment.

The reduction of oil uptake in vacuum-fried Pleurotus eryngii chips by ultrasound assisted pretreatment was investigated regarding the pore structure changes. Pore structure of P. eryngii chips with four pretreatments, such as blanching, blanching + osmosis, blanching + ultrasound and blanching + ultrasound assisted osmosis was determined by mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). In addition, the quality parameters of vacuum-fried P. eryngii chips such as hardness, rehydration ratio, reducing sugar, protein and oil content were also measured. The results showed that the oil absorption of vacuum fried P. eryngii chips was affected by the porous structure. The oil content of vacuum fried P. eryngii chips was significantly and positively correlated with the pores with diameters above 50, 5-50, and 0.5-5 µm in the samples both before and after vacuum frying, while negatively correlated with the pores with diameters below 0.5 µm. Ultrasound pretreatment changed the microporous structure of P. eryngii chips, effectively hindering the oil absorption of samples. In particular, ultrasound assisted osmosis pretreatment induced the formation of more micropores. It was concluded that blanching + ultrasound assisted osmosis pretreatment is a promising method to reduce oil absorption and improve the quality of vacuum fried foods.

Flavor properties of Chinese noodles processed by dielectric drying.

Volatile organic compounds (VOCs) significantly impact food flavor. In this work, Electron nose (E-nose), head space solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS), and head space-gas chromatography-ion mobility spectrometry (HS-GC-IMS) techniques were applied to analyze different drying effects: microwave, hot air, and radio frequency on the aroma of Chinese noodles. E-nose analysis suggests that aromatic differences are mainly from broad range-methane. HS-SPME-GC-MS and HS-GC-IMS identified 47 and 26 VOCs in the fresh and dried noodles, respectively. The VOCs in the dried noodles were mainly aldehydes, alcohols, and esters. Drying significantly reduced the types of VOCs in Chinese dried noodles. Microwave dried noodles exhibited the strongest aroma after the shortest time of treatment, suggesting microwave drying may be the best drying method for noodles. Using aromatic analysis, this paper provides useful information for understanding the flavor of flour products and offers new ideas for drying noodles.

Effects of different proteins and maltodextrin combinations as wall material on the characteristics of Cornus officinalis flavonoids microcapsules.

The flavonoids in Cornus officinalis (CO) have various pharmacological activities, however, the flavonoid instability limits its application in food and pharmaceutical industries. In this study, Cornus officinalis flavonoid (COF) microcapsules were prepared by using a combination of whey isolate protein (WPI), soy isolate protein (SPI), gelatin (GE), and maltodextrin (MD) as wall materials, respectively. Meanwhile, the encapsulation efficiency, solubility, color, particle size, thermal stability and microstructure as well as the antioxidant capacity of microcapsules were assessed. When the protein/MD ratio was 3:7, three kinds of combined wall materials realized high encapsulation efficiency (96.32-98.24%) and water solubility index (89.20-90.10%). Compared with other wall material combinations, the microcapsules with WPI-MD wall ratio at 3:7 had lower particle size (7.17 µm), lower moisture content (6.13%), higher encapsulation efficiency (98.24%), better water solubility index (90.1%), higher thermal stability (86.00°C), brightness L* (67.84) and higher 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging capacity (6.98 mgVc/g), and better flowability. Results suggested that WPI and MD could be better wall materials applied in encapsulating COF.

Physicochemical, Pasting Properties and In Vitro Starch Digestion of Chinese Yam Flours as Affected by Microwave Freeze-Drying.

Microwave freeze-drying (MFD) is a new freeze-drying technique, which differs from single microwave treatment; it involves simultaneous effects of microwave power, time, and the moisture state applied to the materials. In this study, the effects of MFD under various microwave power densities (0.5, 1.0, and 1.5 W/g) on the drying characteristics of Chinese yam slices and the physicochemical, pasting, and thermal properties as well as the starch digestibility of the flour were investigated using conventional hot air drying (HAD) at 50 °C as a control. Compared to HAD, MFD shortened the drying time up to 14.29~35.71%, with a higher drying efficiency at a high microwave power density (1.5 W/g). MFD yam flours provided benefits over HAD products in terms of color, water/oil absorption capacity, and solubility, exhibiting high hot-paste viscosity but low resistant starch content. The content of total starch and free glucose of the yam flour and its iodine blue value were significantly influenced by the drying method and the MFD process parameters (p < 0.05). MFD processing could disrupt the short-range ordered structure of yam starch. Among the MFD flours, samples dried by MFD at 1.5 W/g presented the highest ratio of peak intensity at 1047 and 1022 cm−1 (R1047/1022) value, gelatinization enthalpy, and resistant starch content. These results gave a theoretical foundation for the novel freeze-drying method that MFD applied to foods with a high starch content, enabling the production of a product with the desired quality.