Optimizing Extraction Conditions of Free and Bound Phenolic Compounds from Rice By-Products and Their Antioxidant Effects

Grain bound polyphenols: Molecular interactions, release characteristics, and regulation mechanisms of postprandial hyperglycemia

Frequent postprandial hyperglycemia causes many chronic diseases. Grain polyphenols are widely recognized as natural active ingredients with high potential to treat chronic diseases due to their excellent postprandial hyperglycemic regulating effects. However, previous studies on polyphenols in grains mainly focused on the functional properties of free polyphenols and the extraction and physicochemical properties of bound polyphenols, ignoring the functional properties of bound polyphenols. Comprehensively understanding the binding properties of grain bound polyphenols (GBPs) and their mechanisms in regulating blood glucose levels is essential for developing and applying grain resources. This review summarizes the molecular interactions between GBPs and grain components and their effects on release characteristics and bioavailability at various stages. Meanwhile, the review focuses on elucidating the regulatory mechanism of post-release GBPs on postprandial hyperglycemia levels, incorporating insights from molecular docking, the gastrointestinal-brain axis, and gut flora. GBPs slow food digestion by occupying the active site of digestive enzymes and altering the secondary structure of enzymes and the hydrophobic environment of amino acid residues to inhibit enzyme activity. They modulate intestinal epithelial transport proteins (SGLT1, GLUT2, and GLUT4) to limit glucose absorption and increase glucose consumption. They also stimulate the release of short-term satiety hormones (CKK, GLP-1, and PYY) through the gastrointestinal-brain axis to decrease post-meal food intake. Furthermore, they optimize gut microbiota composition, promoting short-chain fatty acid production and bile acid metabolism. Therefore, developing functional foods with glucose-modulating properties based on GBPs is crucial for obesity prevention, diabetes management, and low-GI food development.

Physical properties and oxidative stability of mayonnaises fortified with natural deep eutectic solvent, either alone or enriched with pigmented rice bran

This article explores the novel use of natural deep eutectic solvents (NaDES) in real food by incorporating them into mayonnaise, either alone or with pigmented rice bran (RB). Results showed that NaDES-fortified mayonnaises could prevent lipid oxidation. Notably, mayonnaises with NaDES2 (betaine:sucrose:water) significantly reduced the production of lipid hydroperoxides, which was maintained to an average of 2.6 mmol LOOH/kg oil, which is 2.9 times lower than the control (7.5 mmol LOOH/kg oil), or 7.4 times lower than mayonnaise with citric acid (19.1 mmol LOOH/kg oil). NaDES2-fortified mayonnaises maintained high tocopherols levels (0.97 g/Kg oil) and reduced volatile compounds from secondary lipid oxidation. This effect may result from NaDES altering the aqueous phase properties of mayonnaise, notably by reducing water activity by ∼0.1. Finally, pre-enrichment of the NaDES phase with bioactive molecules (e.g. from pigmented RB) represents an innovative perspective to promote the health benefits of formulated foods.

Polysaccharide-polyphenol interactions: a comprehensive review from food processing to digestion and metabolism

Most studies on the beneficial effects of polyphenols on human health have focused on polyphenols extracted using aqueous organic solvents, ignoring the fact that a portion of polyphenols form complexes with polysaccharides. Polysaccharides and polyphenols are interrelated, and their interactions affect the physicochemical property, quality, and nutritional value of foods. In this review, the distribution of bound polyphenols in major food sources is summarized. The effect of food processing on the interaction between polyphenols and cell wall polysaccharides (CWP) is discussed in detail. We also focus on the digestion, absorption, and metabolic behavior of polysaccharide-polyphenol complexes. Different food processing techniques affect the interaction between CWP and polyphenols by altering their structure, solubility, and strength of interactions. The interaction influences the free concentration and extractability of polyphenols in food and modulates their bioaccessibility in the gastrointestinal tract, leading to their major release in the colon. Metabolism of polyphenols by gut microbes significantly enhances the bioavailability of polyphenols. The metabolic pathway and product formation rate of polyphenols and the fermentation characteristics of polysaccharides are affected by the interaction. Furthermore, the interaction exhibits synergistic or antagonistic effects on the stability, solubility, antioxidant and functional activities of polyphenols. In summary, understanding the interactions between polysaccharides and polyphenols and their changes in food processing is of great significance for a comprehensive understanding of the health benefits of polyphenols and the optimization of food processing technology.

Phenolic composition and antioxidant capacity of betel inflorescence extract in a simulated oral environment

The addition of betel inflorescence (BI) and slaked lime (calcium hydroxide) to betel quid (BQ) formulation may be detrimental to human health. Here, we assessed BI extracts prepared using artificial saliva or aqueous solution with or without adding slaked lime to mimic the release of phytochemicals from BI in the oral cavity. The extracts were also profiled by HPLC-DAD-ESI-QTOF-MS/MS to understand the quality and quantity of phytochemicals released. The results indicate that slaked lime facilitates the extraction of phenolics, likely due to a high pH. In a simulated oral environment with artificial saliva, the addition of slaked lime promotes the release of safrole, a well-known carcinogen. Dominant phytochemicals detected also include eugenol, acetyl eugenol and methyl eugenol, and only a fraction of these compounds is released in the simulated oral environment. This study reveals that environmental conditions can considerably affect the extraction of phytochemicals and triggers further investigation on how chewing practices may influence the release and activity of carcinogens.

Evaluation of Antibacterial and Antibiofilm Activity of Rice Husk Extract against Staphylococcus aureus

Infections caused by Staphylococcus aureus are particularly difficult to treat due to the high rate of antibiotic resistance. S. aureus also forms biofilms that reduce the effects of antibiotics and disinfectants. Therefore, new therapeutic approaches are increasingly required. In this scenario, plant waste products represent a source of bioactive molecules. In this study, we evaluated the antimicrobial and antibiofilm activity of the rice husk extract (RHE) on S. aureus clinical isolates. In a biofilm inhibition assay, high concentrations of RHE counteracted the formation of biofilm by S. aureus isolates, both methicillin-resistant (MRSA) and -sensitive (MSSA). The observation of the MRSA biofilm by confocal laser scanning microscopy using live/dead cell viability staining confirmed that the bacterial viability in the RHE-treated biofilm was reduced. However, the extract showed no or little biofilm disaggregation ability. An additive effect was observed when treating S. aureus with a combination of RHE and oxacillin/cefoxitin. In Galleria mellonella larvae treated with RHE, the extract showed no toxicity even at high concentrations. Our results support that the rice husk has antimicrobial and antibiofilm properties and could potentially be used in the future in topical solutions or on medical devices to prevent biofilm formation.

Rice Byproduct Compounds: From Green Extraction to Antioxidant Properties

Currently, rice (Oryza sativa L.) production and consumption is increasing worldwide, and many efforts to decrease the substantial impact of its byproducts are needed. In recent years, the interest in utilizing rice kernels, husk, bran, and germ for the recovery of different molecules, from catalysts (to produce biodiesel) to bioactive compounds, has grown. In fact, rice byproducts are rich in secondary metabolites (phenolic compounds, flavonoids, and tocopherols) with different types of bioactivity, mainly antioxidant, antimicrobial, antidiabetic, and anti-inflammatory, which make them useful as functional ingredients. In this review, we focus our attention on the recovery of antioxidant compounds from rice byproducts by using innovative green techniques that can overcome the limitations of traditional extraction processes, such as their environmental and economic impact. In addition, traditional assays and more innovative methodologies to evaluate the antioxidant activity are discussed. Finally, the possible molecular mechanisms of action of the rice byproduct antioxidant compounds (phenolic acids, flavonoids, γ-oryzanol, and vitamin E) are discussed as well. In the future, it is expected that rice byproduct antioxidants will be important food ingredients that reduce the risk of the development of several human disorders involving oxidative stress, such as metabolic diseases, inflammatory disorders, and cancer.

Acid hydrolysis conditions do affect the non-extractable phenolic compounds composition from grape peel and seed

This study aimed to evaluate the effect of hydrolysis conditions on non-extractable phenolic compounds (NEPC) composition of grape peel and seed powder. The effect of temperature (50-90 °C), hydrochloric acid concentration (0.1-15.0 %), and time (5-20 min) were evaluated to understand their impact on NEPC release/extraction and degradation. The use of 1.0 and 8.0 % of HCl concentrations (v/v) and temperatures of 65 and 80 °C produced extracts with higher concentrations and a larger set of compounds. These conditions promoted a balance between release/extraction and degradation processes, thereby maximizing the NEPC content in the extracts. Furthermore, the results suggest that hydrolysis conditions can be set to modulate the release of specific classes. Non-extractable proanthocyanidins showed higher concentrations when intermediate values of temperature and acid concentration were applied. Hydrolysable tannins and hydroxybenzoic acids, on the other hand, were better extracted using higher acid concentrations and higher temperatures. The results suggest that the concentration and composition of NEPC are influenced by the hydrolysis conditions and the type of matrix. Hence, it is crucial to account for this compositional variation when conducting research on the biological effects of NEPC and when using this fraction as supplements or food ingredients.

Impact of High-Pressure Homogenization on Enhancing the Extractability of Phytochemicals from Agri-Food Residues

The primary objective of the Sustainable Development Goals is to reduce food waste by employing various strategies, including the reuse of agri-food residues that are abundantly available and the complete use of their valuable compounds. This study explores the application of high-pressure homogenization (HPH), an innovative nonthermal and green treatment, for the recovery of bioactive compounds from agri-food residues. The results demonstrate that the optimized HPH treatment offers advantages over conventional solid/liquid extraction (SLE), including shorter extraction time, solvent-free operation, low temperatures, and higher yields of phenol extraction (an approximately 20% improvement). Moreover, the micronization of agri-food residue-in-water suspensions results in a decrease in the size distribution to below the visual detection limit, achieved by disrupting the individual plant cells, thus enhancing suspension stability against sedimentation. These findings highlight the potential of HPH for environmentally friendly and efficient extraction processes.

Optimizing extraction conditions and isolation of bound phenolic compounds from corn silk (Stigma maydis) and their antioxidant effects

During the processing of maize, Stigma maydis, also known as corn silk, is normally discarded as waste. Phytochemical research was carried out on the S. maydis to use it as a valuable source of bioactive components. This research aimed to maximize the recovery of free and bound phenolic compounds from corn silk under optimal experimental conditions. Response surface design was operated to optimize the alkaline hydrolysis extraction of bound phytochemicals from corn silk based on total phenolic content and DPPH radical scavenging activity. The optimum conditions (i.e., NaOH concentration 2 M, digestion time 135 min, digestion temperature of 37.5°C, the solid-to-solvent ratio of 1:17.5, and acetone) were obtained. The optimum parameters were used to extract the corn silk. The structures of two compounds isolated from ethyl acetate extracts were then identified as friedelin (1) and (E)-4-(4-hydroxy-3-methoxyphenyl) but-3-en-2-one (2). The DPPH, H₂ O₂ , and ABTS % inhibition of the compounds is as follows: compound (1) 74.81%, 76.8%, 70.33% and compound (2) 70.37%, 56.70% and 57.46%, respectively. The current study has opened previously unexplored perspectives of the composition of bound compounds in corn silk and established the foundations for more effective processing and utilization of corn waste. PRACTICAL APPLICATION: Bound phenolic compounds from corn silk under optimal experimental conditions were obtained. Corn silk can be utilized as a type of medicinal herb as well as a source of inexpensive natural antioxidants.

Recent advances in bio-based extraction processes for the recovery of bound phenolics from agro-industrial by-products and their biological activity

Usually found bound to other complex molecules (e.g., lignin, hemicellulose), phenolic compounds (PC) are widely present in agro-industrial by-products, and their extraction is challenging. In recent times, research is starting to highlight the bioactive roles played by bound phenolics (BPC) in human health. This review aims at providing a critical update on recent advances in green techniques for the recovery of BPC, focusing on enzymatic-assisted (EAE) and fermentation-assisted extraction (FAE) as well as in the combination of technologies, showing variable yield and features. The present review also summarizes the most recent biological activities attributed to BPC extracts until now. The higher antioxidant activity of BPC-compared to FPC-coupled with their affordable by-product source make them medicinally potent and economically viable, promoting their integral upcycling and generating new revenue streams, business, and employment opportunities. In addition, EAE and FAE can have a biotransformative effect on the PC itself or its moiety, leading to improved extraction outcomes. Moreover, recent research on BPC extracts has reported promising anti-cancer and anti-diabetic activity. Yet further research is needed to elucidate their biological mechanisms and exploit the true potential of their applications in terms of new food products or ingredient development for human consumption.

In vitro and in vivo glycemic responses and antioxidant potency of acorn and chickpea fortified gluten-free breads

Gluten-free (GF) breads, based on rice flour and corn starch (50:50), were fortified with a mixture of acorn flour (ACF) - chickpea flour (CPF) at 30% substitution level of corn starch (i.e., rice flour:corn starch:ACF-CPF 50:20:30) using different flour blends of ACF:CPF at weight ratios of 5:25, 7.5:22.5, 12.5:17.5, and 20:10 in order to improve the nutritional quality and antioxidant potential as well as the glycemic responses of the GF breads; a control GF bread with rice flour:corn starch 50:50 ratio was also prepared. ACF was richer in total phenolic content than CPF, whereas CPF was characterized by higher amounts of total tocopherols and lutein compared to ACF. For both ACF and CPF as well as the fortified breads, the most abundant phenolic compounds were gallic (GA) and ellagic (ELLA) acids as found by HPLC-DAD analysis, while a hydrolysable tannin, valoneic acid dilactone, was also identified and quantified by HPLC-DAD-ESI-MS in high amount in the ACF-GF bread having the highest level of ACF (ACF:CPF 20:10), even though it seemed to decompose during breadmaking, possibly into GA and ELLA. Therefore, the inclusion of these two raw materials as ingredients in GF bread formulations resulted in baked products with enhanced concentrations of such bioactive compounds and higher antioxidant activities, as indicated by three different assays (DPPH, ABTS and FRAP). The extent of glucose release, as evaluated by an in vitro enzymic assay, was negatively correlated (r = -0.96; p = 0.005) with the level of added ACF, and was significantly reduced for all ACF-CPF fortified products when compared with their non-fortified GF counterpart. Furthermore, the GF bread containing a flour mixture of ACP:CPF at a weight ratio of 7.5:22.5, was subjected to an in vivo intervention protocol to assess the glycemic response when consumed by 12 healthy volunteers; in this case, white wheat bread was used as reference food. The glycemic index (GI) of the fortified bread was significantly lower compared to the control GF bread (97.4 versus 159.2, respectively), which along with its lower amount of available carbohydrates and the higher level of dietary fibers, resulted in a significantly reduced glycemic load (7.8 versus 18.8 g per serving of 30 g). The present findings underlined the effectiveness of acorn and chickpea flours in improving the nutritional quality and glycemic responses of fortified GF breads with these flours.

Valorization of Rice Husk (Oryza sativa L.) as a Source of In Vitro Antiglycative and Antioxidant Agents

Rice husk is a good source of polyphenols, but it has not been efficiently utilized in food applications yet. Therefore, the aim of this work is to investigate, by in vitro assays, the polyphenolic extract (RHE) capacity of this waste to counteract the protein glycation at different stages of the reaction, correlating this activity with the antiradical properties. A microwave-assisted extraction using hydro-alcoholic solvents was applied to recover husk polyphenols. Extraction parameters were optimized by the design of the experiment. The extract with the highest polyphenolic recovery was obtained at 500 W and 90 °C, using 1:35 g of dry material/mL solvent, 80% ethanol, and a 5 min extraction time. Results highlight the ability of RHE to inhibit the formation of fructosamine in the early stage of glycation with a dose-dependent activity. Furthermore, in the middle stage of the reaction, the highest RHE tested concentration (2.5 mg/mL) almost completely inhibit the monitored advanced glycation end products (AGEs), as well as showing a good trapping ability against α-dicarbonyl intermediates. A strong positive correlation with antioxidant activity is also found. The obtained results are supported by the presence of ten polyphenols detected by RP-HPLC-DAD-ESI-MSⁿ, mainly hydroxycinnamic acids and flavonoids, already reported in the literature as antiglycative and antioxidant agents.

New insights into non-extractable phenolic compounds analysis

Most of the studies regarding phenolic compounds (PC) have been focused only on one fraction of PC, named extractable phenolic compounds (EPC). As the name suggests, EPC can be directly extracted from the food matrix by using an appropriate solvent. Otherwise, non-extractable phenolic compounds (NEPC) remain in the food matrix after the conventional extraction, and their analysis depends on a hydrolysis process. NEPC is a relevant fraction of PC that acts in the colon, where they are extensively fermented by the action of the microbiota. To understand the health effects associated with the NEPC intake, it is necessary to know which types of compounds are present and their content in foods. In this review, 182 studies published in the last five years about NEPC in foods were evaluated, focusing on critical points of the NEPC analysis. First, EPC exhaustive extraction should be performed before the hydrolysis processes to avoid overestimation of the NEPC fraction. NEPC hydrolysis by aggressive methods modifies their original structure and makes their complete elucidation difficult. These methods must be optimized considering the research objective, as different conditions may result in different amounts and profiles of compounds. Concerning quantification, the widely used spectrophotometric Folin-Ciocalteu method should be avoided as it leads to overestimation. Liquid chromatography coupled to a diode array detector is the most appropriate technique for this purpose. Although pure standard compounds are unavailable in most cases, standards representative of a PC family can be used, and results can be expressed as equivalent. The best approach for NEPC identification is liquid chromatography coupled to a diode array detector and tandem high-resolution mass spectrometry, which generates information regarding chromatographic behavior, UV-vis absorption, accuracy mass and fragmentation pattern. The identification process should associate manual data handling with the bioinformatics-assisted approach.

Comparison and Optimization of Different Extraction Methods of Bound Phenolics from Jizi439 Black Wheat Bran

Diet rich in phenolics would potentially associate with multiple health benefits. Response surface methodology (RSM) was introduced to optimize the process of ultrasound- and microwave-assisted extraction of bound phenolics from the bran of a newly developed black wheat breeding line Jizi439 and then compared with the traditional alkaline method. The optimum conditions were found to be 66 °C, 48 min, and power 240 W for ultrasound-assisted extraction (UAE), and 120 s, power 420 W for microwave-assisted extraction (MAE), respectively. Total bound phenolic contents (TBPCs), determined by Folin-Ciocalteu reagent, were 8466.7 ± 240.9 μg gallic acid equivalents per gram (μg GAE/g) bran for UAE and 8340.7 ± 146.7 μg GAE/g bran for MAE under optimized conditions, which were both significantly higher than that of the traditional method (5688.9 ± 179.6 μg GAE/g) (p < 0.05). Antioxidant activities (AAs) were determined by DPPH and ABTS methods. UAE extracts showed the highest DPPH scavenging activity (77.5 ± 0.9%), while MAE extracts showed the highest ABTS scavenging activity (72.1 ± 0.6%). Both were significantly higher than that of the traditional method (69.6 ± 1.1% for DPPH and 65.9 ± 0.5% for ABTS) (p < 0.05). Total bound phenolics (TBPs) profiles were further analyzed by HPLC, and results indicated that ferulic acid was dominant, followed by vanillic acid and p-coumaric acid. The contents of each identified individual phenolics were significantly increased by ultrasound and microwave. In conclusion, UAE and MAE were comparable with each other in TBP yields and AAs; however, when taking operation time and energy consumption into consideration, MAE was more efficient than UAE. Our study suggested efficiency extraction methods for further use of bound phenolics as a healthy food ingredient.

Development and Optimisation of Solid-Phase Extraction of Extractable and Bound Phenolic Acids in Spelt (Triticum spelta L.) Seeds

A solid-phase extraction (SPE) technique was developed and optimised for isolation and concentration of extractable and bound phenolic acids from germinated spelt seeds, for analysis by liquid chromatography–mass spectrometry. Samples initially underwent solvent extraction under different conditions to maximise the yield of phenolic antioxidants. Optimal extraction conditions for extractable phenolics were absolute methanol as solvent, sample-to-methanol ratio 1:9, and reconstitution in non-acidified water. The bound phenolics were extracted from sample pellets using hydrolysis with 2 M NaOH, acidification of the hydrolysate with formic acid, and simultaneous isolation and purification using Strata X polymeric RP tubes. Compared to liquid-liquid extraction, this direct SPE protocol has significant advantages in terms of higher extraction efficiencies of total and individual phenolics and their antioxidant activities. These data suggest that direct SPE represents a rapid and reliable method for quantitative analysis of both the extractable and the commonly overlooked bound phenolics in Triticum spelta seeds.

Bound Polyphenols from Insoluble Dietary Fiber of Defatted Rice Bran by Solid-State Fermentation with Trichoderma viride: Profile, Activity, and Release Mechanism

This study is aimed at exploring the release of bound polyphenols (BP) from insoluble dietary fiber (IDF) and its mechanism by solid-state fermentation (SSF) via Trichoderma viride. The results indicated that BP released by SSF (5.55 mg GAE/g DW) was significantly higher than by alkaline hydrolysis. In addition, 39 polyphenols and catabolites were detected, and the related biotransformation pathways were speculated. Quantitative analysis showed that SSF released more ferulic acid, p-coumaric acid, and organic acids, which led to advances in antioxidant, α-amylase, and α-glucosidase inhibitory activities. Furthermore, structural characteristics (scanning electron microscopy, X-ray diffraction, thermos gravimetric analysis, and Fourier transform infrared spectroscopy) and dynamic changes of carbohydrate-hydrolyzing enzymes indicated that the destruction of hemicellulose and the secretion of xylanase were vital for releasing BP. Overall, this study demonstrated that SSF was beneficial to release BP from IDF, which could provide insight into utilizing agricultural byproducts in a more natural and economical way.

Role of nutraceutical starch and proanthocyanidins of pigmented rice in regulating hyperglycemia: Enzyme inhibition, enhanced glucose uptake and hepatic glucose homeostasis using in vitro model

Dysregulation of glucose homeostasis result in hyperglycemia and pigmented rice, unique combination of high quality starch and phenolics has the potential in regulating it. In this study, pigmented rice was characterized in terms of nutraceutical starch (NS) and phenolic content. Further the effect of rice phenolics on carbolytic enzyme inhibition, glucose uptake, hepatic glucose homeostasis and anti-glycation ability was analyzed in vitro. The most relevant effect on enzyme inhibition (α-amylase: IC₅₀-42.34 µg/mL; α-glucosidase: IC₅₀:63.89 µg/mL), basal uptake of glucose (>39.5%) and anti-glycation ability (92%) was found in red rice (RR), than black rice (BR). The role of RR phenolics in regulating glucose homeostasis was deciphered using hepatic cell line system, which found up-regulation of glucose transporter 2 (GLUT2) and glycogen synthase 2 (GYS2); while expression of gluconeogenic genes were found down regulated. To our knowledge this study is the first report validating the role of starch-phenolic quality towards anti-hyperglycemic effect of RR.

Bioactive Components and Antioxidant Activity Distribution in Pearling Fractions of Different Greek Barley Cultivars

In this study, three pearling fractions, namely bran, dehulled grains and pearled grains, derived from fourteen hulled and one hull-less Greek barley cultivars (Hordeum vulgare L.), were analyzed for the protein, ash, β-glucan, phenolic compounds and tocols contents. High variations appeared in the bioactive contents across the barley cultivars and fractions as well. The protein and ash contents decreased from the outer to the inner layers, whereas β-glucans presented an inverse trend. The highest protein and β-glucan contents were in the hull-less cultivar; however, one hulled cultivar (Sirios) exhibited similar β-glucan content, while another (Constantinos) had even higher protein content. The results also revealed that functional compounds were mainly located in bran fraction. Similar trends were also noted for the antioxidant activity. Ferulic acid was the primary phenolic acid in all fractions, followed by sinapic and p-coumaric acids that were dominant in bound form. However, oligomeric flavonoids, such as prodelphinidin B₃, catechin, and procyanidin B_2, were more abundant in free form. Overall, this study highlights that different barley cultivars can provide pearling flour fractions of varying composition (nutrients and bioactives), which have the potential to serve as nutritionally valuable ingredients in formulations of cereal-based functional food products.

Recovery of Polyphenols from Brewer's Spent Grains

The recovery of antioxidant polyphenols from light, dark and mix brewer’s spent grain (BSG) using conventional maceration, microwave and ultrasound assisted extraction was investigated. Total polyphenols were measured in the crude (60% acetone), liquor extracts (saponified with 0.75% NaOH) and in their acidified ethyl acetate (EtOAc) partitioned fractions both by spectrophotometry involving Folin–Ciocalteu reagent and liquid-chromatography-tandem mass spectrometry (LC-MS/MS) methods. Irrespective of the extraction methods used, saponification of BSG yielded higher polyphenols than in the crude extracts. The EtOAc fractionations yielded the highest total phenolic content (TPC) ranging from 3.01 ± 0.19 to 4.71 ± 0.28 mg gallic acid equivalent per g of BSG dry weight. The corresponding total polyphenols quantified by LC-MS/MS ranged from 549.9 ± 41.5 to 2741.1 ± 5.2 µg/g of BSG dry weight. Microwave and ultrasound with the parameters and equipment used did not improve the total polyphenol yield when compared to the conventional maceration method. Furthermore, the spectrophotometric quantification of the liquors overestimated the TPC, while the LC-MS/MS quantification gave a closer representation of the total polyphenols in all the extracts. The total polyphenols were in the following order in the EtOAc fractions: BSG light > BSG Mix > BSG dark, and thus suggested BSG light as a sustainable, low cost source of natural antioxidants that may be tapped for applications in food and phytopharmaceutical industries.

Rice Flour and Bran Enriched with Blueberry Polyphenols Increases Storage Stability and Decreases Arsenic Content in Bran

A low-cost method utilizing rice co-products to concentrate and stabilize blueberry polyphenols was developed that decreased the arsenic (As) content in rice bran. After concentration at 10 g/L, brown rice flour displayed a higher total anthocyanin content in both blueberry juice (2.7 mg/g) and pomace extract (2.6 mg/g) when compared to white rice flour. Defatted rice bran enriched with blueberry juice (10 g/L) had the highest concentration of polyphenols (16.0 mg/g), and defatted bran enriched with pomace extract had the highest concentration of anthocyanins (5.32 mg/g). Enriched rice flour and bran contained higher levels of anthocyanins when using pomace extracts. Polyphenols and anthocyanins were found to be highly stable at 37 °C in rice flour and bran samples combined with pomace extract. Polyphenol enrichment also produced lower total and inorganic arsenic (i-As) levels in defatted rice bran. Inorganic arsenic (i-As) concentrations in defatted rice bran enriched with blueberry juice and pomace extracts were reduced by 20.5% and 51.6%, respectively. Overall, rice flour and bran that are enriched with polyphenols and anthocyanins from blueberry pomace extracts are shelf and color stable, had low sugar content, and represent unique health-promoting food ingredients.

Extraction Optimization of Phenolics and Antioxidants from Black Goji Berry by Accelerated Solvent Extractor Using Response Surface Methodology

This study aims to provide fundamental knowledge for the use of black goji berry and determine the optimum process parameters that produce maximum phenolics from black goji berry through accelerated solvent extraction (ASE). The optimal extractions of phenolics and antioxidants from black goji were explored via the ASE techniques, applying the response surface methodology (RSM) design. After reaching the optimal conditions for single factors, the optimal ASE extraction conditions were found through a total of 17 runs following the Box-Behnken design (BBD) from RSM. The maximum yield of total phenolic content (TPC) was 17.92 mg GAE/g under the best extraction conditions: an extraction temperature of 89.38 °C, an ethanol concentration of 70% and an extraction time of 13 min. This study indicates that the optimal extraction conditions could serve as the scientific basis for scaled-up industrial production. Black goji berry could be a viable source of nutraceuticals due to the abundance of antioxidant and phenolic substances.