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Plant-derived antioxidants (PD-AOs) are important for food preservation, as well as for human health and nutrition. However, the poor chemical stability and water solubility of many PD-AOs currently limit their application as functional ingredients in foods and pharmaceuticals. Moreover, it is often difficult to isolate and detect specific antioxidants in multi-component systems, which again limits their potential in the food and medical industries. In this review, we highlight recent advances in the use of cyclodextrins (CDs) to overcome these limitations by forming simple, modified and competitive host-guest interactions with PD-AO. The host-guest properties of CDs can be used to enhance the separation efficiency of PD-AOs, as well as to improve their dispersion and stability in food systems. Moreover, the competitive complexation properties of CDs with target molecules can be used to selectively isolate PD-AOs from multi-component systems and develop detection technologies for PD-AOs. Overall, CD-antioxidant interactions have great potential for addressing isolation, detection, and food quality issues.

Vaccinium bracteatum Thunb.leaves (VBTL) are a traditional Chinese herbal medicine with potential natural pigments and antioxidants. Its application information on extrusion is limited. In this study, to increase the usage of foods containing VBTL, rice-based extrudates with VBTL were investigated. The extrusion was performed at a wide temperature range (60-140°C) and with different VBTL supplementations (3%-10%). The extrudates with 10% VBTL showed a significant decrease in total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity upon extrusion. TPC and TFC increased with the rise of barrel temperature. The VBTL color was stable during the wide-temperature extrusion process. The bioactivities of the extrudates were positively correlated with the VBTLsupplement (R = 0.943-0.989). In addition, different addition levels of VBTL significantly changed the water absorption index (WAI), water solubility index (WSI), pasting properties, and in vitro starch digestibility of the extrudates. Moreover, extrudates with 3% VBTL showed the highest WAI and peak viscosity but the lowest in vitro starch digestibility. These results may suggest that rice extrudates with a low supplement of VBTL have an acceptable color and may be used as functional additives for high antioxidant and low glycemic response diets. PRACTICAL APPLICATION: The results showed that the Vaccinium bracteatum Thunb. leaves (VBTL) color and antioxidation were stable during the wide-temperature extrusion process. Extrusion processing can be used to enlarge the usage of VBTL and simplify its traditional processing method. Applying VBTL to the process of extrusion appears to be a suitable method of producing value-added and low glycemic response extrudates., (© 2021 Institute of Food Technologists®.)

For the purpose of investigating the effect of enzyme concentration (EC), barrel temperature (BT), moisture content (MC), and screw speed (SS) on processing parameters (product temperature, die pressure and special mechanical energy (SME)) and product responses (extent of gelatinization (GE), retention rate of total phenolic content (TPC-RR)), rice flour extruded with thermostable α-amylase was analyzed by response surface methodology. Stepwise regression models were computed to generate response surface and contour plots, revealing that both TPC-RR and GE increased as increasing MC while expressed different sensitivities to BT during enzymatic extrusion. Phenolics preservation was benefited from low SME. According to multiple-factor optimization, the conditions required to obtain the target SME (10kJ/kg), GE (100%) and TPC-RR (85%) were: EC=1.37‰, BT=93.01°C, MC=44.30%, and SS=171.66rpm, with the actual values (9.49kJ/kg, 99.96% and 87.10%, respectively) showing a good fit to the predicted values., (Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.)

In order to determine the effect of enzymatic extrusion on the physicochemical and antioxidant properties of rice/soybean mixture, different mass ratios (100/0, 95/5, 85/15, 70/30, 50/50 and 25/75%, w/w) were treated with thermostable α-amylase. The reduced special mechanical energy and the enhanced product temperature were closely and regularly linked with the increase of soybean content. The bulk density and water solubility index increased, and the water absorption index and viscosities decreased remarkably after enzymatic extrusion, however, the modification caused by α-amylase were dramatically eliminated with the increase of soybean content to ∼50%. Moreover, the addition of enzyme exhibited an improvement of the total phenolic/flavonoid content (TPC/TFC) and antioxidant capacities compared to traditional extrusion. The TPC/TFC retention of extrudate (ratios of 85/15 and 70/30%) attained over 90%, but dramatically decreased (72.91 and 67.81%, respectively) with soybean added to 75%, probably due to the great reduction of starch substrate for enzymatic hydrolysis., (Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.)

The application of attenuated total reflectance infrared spectroscopy (ATR-IR), Raman spectroscopy (RS) and combination of ATR-IR and RS for measurements of total antioxidant capacity (TAC) and total phenolic content (TPC) of Chinese rice wine (CRW) were investigated in this study. Synergy interval partial least-squares (SiPLS), support vector machine (SVM) and principal component analysis (PCA) were applied to process the merged data from two individual instruments. It was observed that the performances of models based on the RS spectra were better than those based on the ATR-IR spectra. In addition, SVM models based on the efficient information extracted from ATR-IR and RS spectra were superior to PLS models based on the same information and PLS models based on ATR-IR or RS spectra. The overall results demonstrated that integrating ATR-IR and RS was possible and could improve the prediction accuracy of TAC and TPC in CRWs., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

In this study, composite nanoparticles consisting of zein and hydroxypropyl beta-cyclodextrin were prepared using a combined antisolvent co-precipitation/electrostatic interaction method. The effects of calcium ion concentration on the stability of the composite nanoparticles containing both curcumin and quercetin were investigated. Moreover, the stability and bioactivity of the quercetin and curcumin were characterized before and after encapsulation. Fluorescence spectroscopy, Fourier Transform infrared spectroscopy, and X-ray diffraction analyses indicated that electrostatic interactions, hydrogen bonding, and hydrophobic interactions were the main driving forces for the formation of the composite nanoparticles. The addition of calcium ions promoted crosslinking of the proteins and affected the stability of the protein–cyclodextrin composite particles through electrostatic screening and binding effects. The addition of calcium ions to the composite particles improved the encapsulation efficiency, antioxidant activity, and stability of the curcumin and quercetin. However, there was an optimum calcium ion concentration (2.0 mM) that provided the best encapsulation and protective effects on the nutraceuticals. The calcium crosslinked composite particles were shown to maintain good stability under different pH and simulated gastrointestinal digestion conditions. These results suggest that zein–cyclodextrin composite nanoparticles may be useful plant-based colloidal delivery systems for hydrophobic bio-active agents. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of thermostable α-amylase on the rice physicochemical properties, free/bound phenolics, and antioxidant capacities during extrusion, seven different gradients of enzyme concentration from 0 to 6 ‰ (db of starch) were used for both hulled and whole rice. For rice treated with the same extrusion conditions, special mechanical energy (SME) input changed slightly in the presence of fiber fraction (bran/husk), while decreased greatly with increasing α-amylase levels due to the reduced viscosity and friction between mechanical elements and materials. Huge physicochemical modifications were achieved in expansion ratio (ER), bulk density (BD), water absorption/solubility indices (WAI/WSI), and viscosity via enzymatic liquefaction. The total phenolic content (TPC) retention increased dramatically (93.06 and 86.33 % for hulled and whole rice, respectively) with increasing enzyme concentrations to 6 ‰, indicating that a milder reaction environment was created with less thermal-mechanical impact on phenolics. By linear analysis, the TPC of extruded rice hulled or not was strongly and positively related with BD ( R = 0.9185 or 0.9719) and WSI ( R = 0.9719 or 0.8857), whereas negatively related with SME ( R = −0.9460 or −0.8906). Besides, the free/bound phenolics combined with antioxidant activities (1,1-diphenyl-2-picryl-hydrazyl (DPPH), 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid (ABTS), and ferric reducing antioxidant power (FRAP)) were all improved significantly by the separate/synergetic addition of enzyme and bran/husk used as, respectively, the 'special protective agent' and rich source of bioactive compounds. In summary, thermostable α-amylase could achieve many beneficial effects on both physicochemical properties and antioxidant activities of rice extruded with/without fiber for promoting the development of cake making, wine brewing, infant food industries, or animal husbandry. [ABSTRACT FROM AUTHOR]