Improving bioaccessibility and bioavailability of phenolic compounds in cereal grains through processing technologies: A concise review

Olive oil by-product as functional ingredient in bakery products. Influence of processing and evaluation of biological effects

Nowadays, the strong demand for adequate nutrition is accompanied by concern about environmental pollution and there is a considerable emphasis on the recovery and recycling of food by-products and wastes. In this study, we focused on the exploitation of olive pomace as functional ingredient in biscuits and bread. Standard and enriched bakery products were made using different flours and fermentation protocols. After characterization, they were in vitro digested and used for supplementation of intestinal cells (Caco-2), which underwent exogenous inflammation. The enrichment caused a significant increase in the phenolic content in all products, particularly in the sourdough fermented ones. Sourdough fermentation also increased tocol concentration. The increased concentration of bioactive molecules did not reflect the anti-inflammatory effect, which was modulated by the baking procedure. Conventionally fermented bread enriched with 4% pomace and sourdough fermented, not-enriched bread had the greatest anti-inflammatory effect, significantly reducing IL-8 secretion in Caco-2 cells. The cell metabolome was modified only after supplementation with sourdough fermented bread enriched with 4% pomace, probably due to the high concentration of tocopherol that acted synergistically with polyphenols. Our data highlight that changes in chemical composition cannot predict changes in functionality. It is conceivable that matrices (including enrichment) and processing differently modulated bioactive bioaccessibility, and consequently functionality.

Thermal Processing for the Release of Phenolic Compounds from Wheat and Oat Bran

The aim of the present paper was to identify the major polyphenolic compounds and investigate the antioxidant, antimutagenic, and antimicrobial activities of industrially-derived cereal byproducts-wheat bran (WB) and oat bran (OB)-before (fresh) and after thermal processing (TP) (10 min, 80 °C), coupled with ultrasound-asssited extraction. The results showed that the thermal process improved the total phenolic content of WB by +22.49%, and of OB with +25.84%. After the TP, the phenolic concentration showed a significant relative percentage increase in the case of WB (ferulic acid +39.18%, vanillic acid +95.68%, apigenin-glucoside +71.96%, p-coumaric acid +71.91) and of OB (avenanthramide 2c +52.17%, dihydroxybenzoic acids +38.55%). The best antioxidant capacity was registered by OBTP followed by WBTP. The strongest antimicrobial inhibition was attributed to the WBTP sample. Both thermally processed matrices had strong antimutagenic activity toward S. typhimurium TA100. This thermal processing was tested on bran based on its practical application within the food industry, considering the design of different cereal byproducts derived from functional foods and nutraceuticals.

Baked Bread Enhances the Immune Response and the Catabolism in the Human Body in Comparison with Steamed Bread

It is unclear whether different processing methods change the biological functions of foods and how these functions are evaluated in the human body. Here, steamed bread and baked bread, the traditional staple foods in China and many Western countries, were made by steaming and baking, respectively, using one piece of fermented wheat dough and then consumed by 16 healthy young volunteers. By detecting 38 cytokines, 12 metabolic enzymes, glucose, lactate, and nicotinamide adenine dinucleotide (NADH) in the serum, the cytokine network and central metabolic pathway network were investigated to compare the effects of the two staple foods on immunity and metabolism. Compared with steamed bread, baked bread increased (p < 0.05) concentrations of fractalkine and macrophage-derived chemokine, decreased (p < 0.05) the concentration of interleukin-1RA, increased (p < 0.05) the expression level of phosphofructokinase, and decreased (p < 0.05) the expression level of glucose-6-phosphate dehydrogenase in the serum. Two network analyses indicated that baked bread, as compared to the steamed bread, enhanced communication between immune cells, increased catabolism, and decreased anabolism. Further, a correlation analysis of cytokines and metabolic enzymes suggested that the two staple foods may affect metabolism by regulating the secretion of cytokines. These findings highlight how the same raw food material processed by different methods may have different impacts on immunity and metabolism in humans.

The Nutritional Value of Non-Traditional Gluten-Free Flakes and Their Antioxidant Activity

Nowadays, there is a growing interest for foods with a lower sugar content and rich in fiber and biologically active substances. The main purpose of this study was to prepare flakes from non-traditional pigmented cereals (Oryza sativa, Chenopodium quinoa, and Eragrostistef) and to analyze their fibre, sugar, and in vitro digestibility values. Regarding phenolic antioxidants (soluble, soluble conjugated, and insoluble bound fractions), their content and antioxidant activity were measured using spectrophotometry and high performance liquid chromatography (HPLC) methods. Hydrothermally treated grains resulted in flakes with higher total dietary fibre contents (11.1–24.4%), quinoa and teff flakes were rich in maltose (up to 42.0 mg/g). Non-traditional flakes had lower in vitro digestibility, but conversely, they exhibited the highest phenolic contents corresponding with the highest antioxidant activity values (up to 2.33 mg Gallic acid equivalent/g of total phenolic content and 1.59 mg Trolox equivalent/g for 2,2-diphenyl-1-picrylhydrazyl (DPPH) in case of brown teff). Among free phenolics, the main contributors to an antioxidant activity were p-coumaric, o-coumaric, and gallic acids (r > 0.8186); among the soluble conjugated fractions, they were epigallocatechin, epicatechin, caffeic, and vanillic acids (r > 0.5935); while caffeic, protocatechuic, and ferulic acids (r > 0.5751) were the main contributors among the insoluble bound phenolics.

Urinary excretion rate and bioavailability of chlorogenic acid, caffeic acid, p-coumaric acid, and ferulic acid in non-fasted rats maintained under physiological conditions

Hydroxycinnamic acids (HAs) are one of the major classes of phenolic compounds and epidemiological studies have suggested that they have beneficial health effects. This study aimed to determine the urinary excretion rate of chlorogenic acid, caffeic acid, p-coumaric acid, and ferulic acid in non-fasted rats and to estimate their bioavailability under physiological conditions. Previous studies have primarily used fasted animals, which exhibit severe changes in various physiological processes. Furthermore, the food matrix can affect HA bioavailability. Thus, our studies using non-fasted rats under physiological conditions may allow for a more accurate determination of both the HA urinary excretion rate and the bioavailability of HAs. HAs were successively gavaged to rats at a dose of 40 mg/kg body weight (BW) with a wash-out period of one week. The rats were fed the AIN-93M diet throughout the experiment. The urine was collected at time intervals of 0–6 h, 6–24 h, and 24–48 h after HA administration. Ingested HAs, except chlorogenic acid, were primarily excreted in the urine within 0–6 h as free forms or conjugated (glucuronidated and/or sulfated) forms. The majority of the ingested chlorogenic acid was detected in the urine at 6–24 h or 24–48 h as caffeic acid, p-coumaric acid, ferulic acid, and their conjugates. The total urinary excretion rate (% of the dose) at 48 h was ferulic acid (73.2%) > caffeic acid (61.6%) > p-coumaric acid (54.1%) >> chlorogenic acid (4.9%). The percentages of the conjugates in the urine differed amongst the rats gavaged with the individual HAs (74% for chlorogenic acid, 83% for caffeic acid, 68% for p-coumaric acid, and 96% for ferulic acid), which may be explained by their distinct bioactivities. These data reveal that caffeic acid, p-coumaric acid, and ferulic acid are much more bioavailable than chlorogenic acid, even though they are excreted more rapidly than chlorogenic acid. Our findings may provide additional insight into the health benefits of HAs and how they function in the body.

Effect of germination time on antioxidative activity and composition of yellow pea soluble free and polar soluble bound phenolic compounds

This research aims to study antioxidative activities of polar solvent extractable phenolic compounds from yellow peas with different germination times against oil-in-water emulsion oxidation. After germination (0, 2, 4, and 6 days), soluble free and polar soluble bound phenolic compounds were extracted and their antioxidative activity was evaluated using stripped soybean oil (SSO)-in-water emulsions. Liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF-MS) and size-exclusion chromatography with multiangle-light-scattering and refractive-index detection (SEC-MALS-RI) were employed to analyze the phenolic composition and molar mass, respectively. Antioxidative activities of soluble free phenolic compounds increased in the SSO-in-water emulsion system, while those of polar soluble bound phenolic compounds decreased with germination. On the basis of chemometric analysis, pratensein (2), phloridzin (4), quercetin (9), sayanedine (12), hesperetin (13), glyzaglabrin (14), and pinocembrin (15) were speculated as the pivotal phenolic compounds responsible for the hydrogen donating capacity. Additionally, decreased molecular weight of soluble bound phenolic compounds was accompanied by the reduction of antioxidative activity in SSO-in-water emulsions indicating that the moieties of polar soluble bound phenolic compounds also have an important impact on the antioxidative activity of phenolic compounds.

Green consumerism: the influence of antioxidant parameters and socio-economic values on Tarhana consumption patterns

This study aimed to examine the production and consumption patterns of the tarhana as a green food product and its content in terms of health value in the socio-economic framework by comparing urban and rural households. To be able to assess the tarhana's health value, the addition of antioxidative parameters was analysed. We obtained the data as a result of a two-part study. The first part of the research included a structured survey conducted between September and December 2015. In the second part, three types of tarhana samples evaluated in terms of their antioxidant capacity and total phenolic content as extractable, hydrolysable, and bioaccessible phenolics to support the claim that homemade tarhana offers higher nutritional potential and healthier content than commercially produced tarhana. Organic and additive-free homemade tarhana samples have great antioxidative potential, also depending on the content and the production pattern. The results of the antioxidant capacity, total phenolic content analyses, and their bioaccessibility revealed that non-fermented homemade tarhana and cranberry-added tarhana stand out, according to production process and content. Our findings showed that participants mostly produced the tarhana at home. In cases where they could not produce it themselves, they supplied it from their family and friends. This result showed us that participants preferred homemade tarhana over industrial tarhana sold in markets. Rural areas mostly consumed tarhana for its economic value. However, tarhana consumption did not decrease in cities. Only the consumption mode and the times have changed.

Lactic Fermentation as a Strategy to Improve the Nutritional and Functional Values of Pseudocereals

One of the greatest challenges is to reduce malnutrition worldwide while promoting sustainable agricultural and food systems. This is a daunting task due to the constant growth of the population and the increasing demands by consumers for functional foods with higher nutritional values. Cereal grains are the most important dietary energy source globally; wheat, rice, and maize currently provide about half of the dietary energy source of humankind. In addition, the increase of celiac patients worldwide has motivated the development of gluten-free foods using alternative flour types to wheat such as rice, corn, cassava, soybean, and pseudocereals (amaranth, quinoa, and buckwheat). Amaranth and quinoa have been cultivated since ancient times and were two of the major crops of the Pre-Colombian cultures in Latin- America. In recent years and due to their well-known high nutritional value and potential health benefits, these pseudocereals have received much attention as ideal candidates for gluten-free products. The importance of exploiting these grains for the elaboration of healthy and nutritious foods has forced food producers to develop novel adequate strategies for their processing. Fermentation is one of the most antique and economical methods of producing and preserving foods and can be easily employed for cereal processing. The nutritional and functional quality of pseudocereals can be improved by fermentation using Lactic Acid Bacteria (LAB). This review provides an overview on pseudocereal fermentation by LAB emphasizing the capacity of these bacteria to decrease antinutritional factors such as phytic acid, increase the functional value of phytochemicals such as phenolic compounds, and produce nutritional ingredients such as B-group vitamins. The numerous beneficial effects of lactic fermentation of pseudocereals can be exploited to design novel and healthier foods or grain ingredients destined to general population and especially to patients with coeliac disease.

Effect of Different Processing Methods on the Accumulation of the Phenolic Compounds and Antioxidant Profile of Broomcorn Millet (Panicum miliaceum L.) Flour

Broomcorn millet (Panicum miliaceum L.) is an important nutritious ancient minor-cereal food crop. However, this crop is little explored in the food processing arena to improve its functionality. In this context, different processing methods were applied to enhance the secondary compounds of broomcorn millet. Four different individual methods such as roasting, steaming, puffing, and extrusion were applied at 110 °C to enhance the functional attributes of millet flour. It was observed that the significantly highest content of total phenolic (TP) (670 mg/100 g of ferulic acid equivalent) and total flavonoid (TF) (391 mg/100 g of rutin equivalent ) was attained in the roasted whole millet followed by steaming (315 mg/100 g, 282 mg/100 g), puffing (645 mg/100 g, 304 mg/100 g), extrusion (455 mg/100 g, 219 mg/100 g), and control (295 mg/100 g, 183 mg/100 g). The chromatographic analysis showed a greater content of single phenolic acids such as syringic acid, gallic acid, 4-hydroxy benzoic acid, ferulic acid, sinapic acid, and catechin in roasted millet compared to control, and the content of each acid was higher in whole millet than dehulled. Results also indicated that the content of ferulic acid was relatively higher among the quantified single phenolic acid from broomcorn millet. Likewise, in comparison with dehulled millet, the roasted whole millet showed higher total antioxidant capacity, measured by the 2,2-diphenyl-1 picryl hydrazyl (DPPH), the ferric reducing antioxidant power assay (FRAP), the phosphomolybdenum method (PPMD), and the hydroxyl radical scavenging capacity (HRSC) method. Lastly, it is concluded that the roasting method should be taken into consideration in the processing of broomcorn millet to enhance the content of nutraceutical compounds and improve its functionality.

Improvement of cytoprotective and antioxidant activity of L. and L. by controlled differential sieving process against H2O2-induced oxidative stress in mouse primary splenocytes

In this study, cytoprotective and antioxidant activities of Rosa canina (RC) and Salix alba (SA), medicinal plants, were studied on mouse primary splenocytes by comparing Controlled Differential Sieving process (CDSp), which is a novel green solvent-free process, versus a conventional technique, employing hydroethanolic extraction (HEE). Thus, preventive antioxidant activity of three plant powders of homogeneous particle sizes, 50-100 µm, 100-180 µm and 180-315 µm, dissolved directly in the cellular buffer, were compared to those of hydroethanolic (HE) extract, at 2 concentrations (250 and 500 µg/mL) in H₂O₂-treated spleen cells. Overall, compared to HE extract, the superfine powders, i. e., fractions < 180 µm, at the lowest concentration, resulted in greater reactive oxygen species (ROS) elimination, increased glutathione peroxidase (GPx) activity and lower malondialdehyde (MDA) production. Better antioxidant and preventive effects in pre-treated cells were found with the superfine powders for SA (i. e., 50-100 µm and 100-180 µm, both p < 0.001), and with the intermediate powder for RC (i. e., 100-180 µm, p < 0.05) versus HE extract. The activity levels of catalase (CAT) and superoxide dismutase (SOD) in pretreated splenocytes exposed to H₂O₂, albeit reduced, were near to those in unexposed cells, suggesting that pretreatment with the fine powders has relatively restored the normal levels of antioxidant-related enzymes. These findings supported that CDSp improved the biological activities of plants, avoiding the use of organic solvents and thus it could be a good alternative to conventional extraction techniques.

In Vitro Fecal Fermentation of High Pressure-Treated Fruit Peels Used as Dietary Fiber Sources

Fruit by-products are being investigated as non-conventional alternative sources of dietary fiber (DF). High hydrostatic pressure (HHP) treatments have been used to modify DF content as well as its technological and physiological functionality. Orange, mango and prickly pear peels untreated (OU, MU and PPU) and HHP-treated at 600 MPa (OP/55 °C and 20 min, MP/22 °C and 10 min, PPP/55 °C and 10 min) were evaluated. Untreated and treated fruit peels were subjected to fecal in vitro fermentations. The neutral sugar composition and linkage glycosidic positions were related to the production of short chain fatty acids (SCFA) resulting from the fermentation of the materials. After HHP-treatments, changes from multibranched sugars to linear sugars were observed. After 24 h of fermentation, OP yielded the highest amount of SCFA followed by PPU and MP (389.4, 282.0 and 204.6 μmol/10 mg DF, respectively). HHP treatment increased the SCFA concentration of orange and mango peel by 7 and 10.3% respectively, compared with the untreated samples after 24 h of fermentation. The results presented herein suggest that fruit peels could be used as good fermentable fiber sources, because they yielded high amounts of SCFA during in vitro fermentations.

Postprandial Glycaemic and Insulinaemic Responses after Consumption of Activated Wheat and Triticale Grain Flakes

Increasing evidence shows that whole grain consumption is protective against metabolic disorders. Protective bioactive substances of whole grains include fibre and antioxidants. Activation of grains can increase the amount of phenolic compounds and their bioavailability, but there is little evidence about their effect on glycaemic and insulinemic responses. Therefore, the aim of this study was to investigate glycaemic and insulinemic responses after consumption of flakes made from activated wheat and activated triticale grains. Eighteen healthy subjects (7 men and 11 women) were given activated wheat or activated triticale flakes. As a reference, a standard glucose solution was used. Plasma glucose and serum insulin were measured during 120 minutes. Both, activated wheat and activated triticale flakes, show improved glycaemic profile, inducing a lower and more stable glycaemic response. However, statistically significant differences in insulin response were found only in the group who have taken activated triticale flakes and not in the group who have taken activated wheat flakes. Activated triticale flakes induced lower insulin response in all postprandial phases and a more stable concentration of insulin. Thus, activated triticale flakes could be beneficial for the prevention and treatment of metabolic disorders.

Particle size and physical-chemical characteristics of hydrothermally treated cornmeal on resistant starch content

The influence of particle size and chemical composition of three different cornmeals on the resistant starch (RS) content formed during the hydrothermal treatment was studied. The changes in reducing sugars and phenolic acids in different fractions caused by the hydrothermal treatment were correlated with RS content. The cornmeal with smaller particle size had higher RS content (202 mg/g). The hydrothermal treatment promoted a reduction in the total reducing sugars (46.7-84.5%), availability of free phenolic acids (256.7%) and reduction of the bound phenolic acids (71.1%). The correlation between RS contents and phenolic acids was determined by multivariate statistics and principal component analysis (PCA) showed that hydroxybenzoic and ferulic acids influence the formation of RS similar to type 5, amylose-phenol complex. The texture profile parameters (TPA) of cornmeal were negatively correlated with RS and differential scanning calorimetry (DSC) analysis showed consistency with this behavior.

Effect of Precooking and Superheated Steam Treatment on Quality of Black Glutinous Rice

Consumption of glutinous rice has been increasing. Leum Pua rice (Oryza sativa Linn.) is black glutinous rice containing high nutrition, but its cooking process is time-consuming. This study aimed at decreasing cooking time by changing rice properties using superheated steam treatment. The black glutinous rice was subjected to pretreatment: uncooking and precooking before superheated steam treatment at 250°C and 300°C. Drying rate constant (k) of uncooked rice was 0.0301–0.0744 s−1. Precooking rice prior to superheated steam treatment at 300°C reduced the kinetic rate constant to 0.0596 s−1. From SEM, porosity of the treated rice was observed. However, superheated steam treatment reduced ferric reducing antioxidant power and total phenolic content, compared with control. From X-ray diffraction, A-type crystalline structure of the treated rice was disappeared. Cooking time of the superheated steam-treated rice was reduced to 1–5 min. Their hardness and overall liking scores were comparable to control.

Exploitation of autochthonous Tuscan sourdough yeasts as potential starters

The increasing demand for healthy baked goods boosted studies on sourdough microbiota with beneficial metabolic traits, to be used as potential functional starters. Here, yeast populations of traditional sourdoughs collected from four Tuscan bakeries were investigated. Among 200 isolated strains, 78 were randomly selected and molecularly characterized. Saccharomyces cerevisiae was dominant, representing the only species detected in three out of the four sourdoughs. The fourth one harbored also Kazachstania humilis. Inter-delta regions analysis revealed a high intraspecific polymorphism discriminating 16 biotypes of S. cerevisiae isolates, which clustered based on their origin. Representative isolates from each biotype group were individually used to ferment soft and durum wheat flour, aiming at evaluating their pro-technological, nutritional and functional features. During fermentation under standardized conditions, all strains were able to grow of ca. 2 log cycles, but only S. cerevisiae L10Y, D18Y and D20Y had a significantly shorter latency phase in both flours. Overall, the highest volumes were reached after 16 h of fermentation in both soft and durum fermented dough. S. cerevisiae D2Y produced the highest dough volume increase. K. humilis G23Y was the only strain able to increase the total free amino acids concentration of the doughs. Overall, values of phytase activity were significantly higher in durum compared to the corresponding soft fermented dough. K. humilis G23Y and S. cerevisiae D20Y, D24Y showed a threefold higher phytase activity than spontaneously fermented control, and the highest concentration of total phenols. Almost all the strains led to increases of antioxidant activity, without significant differences among them. Investigations on the resistance of the strains to simulated gastric and intestinal conditions, that is considered a pre-requisite for the selection of probiotics, revealed the ability to survive in vitro by many of the strains considered. This study proposed the best performing yeast strains selected among autochthonous sourdough yeasts based on their pro-technological, nutritional and functional traits to be used as starters for making sourdough baked goods or functional cereal-based beverages. Although some yeast strains combined several technological and nutritional traits, the association of more selected strains seemed to be a requisite to get optimal sourdough characteristics.

Hydrothermal stability of phenolic extracts of brown rice

The phenolics were extracted and purified from brown rice and twenty-seven compounds were identified, including six phenolic acids, four phenolic acid glycosides, and eight flavonoid glycosides. Afterwards, the hydrothermal stability of phenolic extracts of brown rice was investigated after treatment at 60, 80, or 100 °C for 120 min. After hydrothermal treatment, ferulic acid, p-coumaric acid and free glucose were increased, while the phenolic glycosides were decreased. In addition, the total phenolic and total flavonoid content were decreased by 5.7%-9.2% and 3.5%-5.8% after initial 30 min, and then they were slightly recovered after treatment for 120 min. Consequently, there was a slight reduction (<10%) in the total antioxidant activity of the phenolic extracts after hydrothermal treatment. These results suggest that hydrothermal treatment of phenolic extracts of brown rice made some phenolic glycosides deglycosylated, but does not lead to a large reduction in their overall antioxidant activity.

In vitro digestibility, free and bound phenolic profiles and antioxidant activity of thermally treated Eragrostis tef L

BACKGROUND

Total phenolic content, phenolic profile and antioxidant activity were determined in free and bound phenolic fractions of thermally treated brown and white teff grains.

RESULTS

Phenolic content in raw brown and white teff (1540 and 992 mg gallic acid equivalent kg^-1 ) as well as antioxidant activity (6.3 and 5.5 mmol trolox equivalent kg^-1 ) were higher in free phenolic fractions. The most significant decrease in total phenolics was observed after application of the sous-vide method (35% for brown teff and 11% for white teff). Main free phenolics of heat-treated teff were ferulic, protocatechuic, p-coumaric and ellagic acids, rutin and epigallocatechin. Main bound phenolics were ferulic, gallic, sinapic and ellagic acids, catechin and epigallocatechin. The detrimental effect on free and bound quercetin and bound cinnamic acid concentrations was also examined during heat treatment. Thermally treated brown teff showed a high level of in vitro organic matter digestibility if water cooking and rice cooker (both 99.5%) and sous-vide (96.5%) methods were applied.

CONCLUSION

The sous-vide method may be recommended as the most suitable hydrothermal treatment for grains of teff when compared with water cooking and rice cooker methods. © 2017 Society of Chemical Industry.

Changes in the functional components and radical scavenging activity of maize under various roasting conditions

The phenolic compounds and radical scavenging activity of ethanolic extracts from maize at various roasting conditions were evaluated in this research. The free sugar contents in roasted maize significantly decreased with higher roasting temperature and longer roasting time. The total polyphenol and total flavonoid contents in roasted maize significantly increased with higher roasting temperature and longer roasting time. The predominant phenolic acid in the roasted maize was homogentisic acid. The contents of homogentisic acid and myricetin in roasted maize significantly increased with higher roasting temperature and longer roasting time. The DPPH and ABTS radical scavenging activities of roasted maize significantly increased with higher roasting temperature and longer roasting time. DPPH and ABTS radical scavenging activities were positively correlated with phenolic compounds. The activities of these components increased following heat treatments because of the low molecularization effects of the heating process, which resulted in active, low-molecular-weight components that were readily extracted.

Powders with small microparticle size from Hedera helix and Scrophularia nodosa exhibited high preventive antioxidant activity against H2O2-induced oxidative stress in mouse primary spleen cells

Abstract. The purpose of this study was to examine the effects of powder particle size on the cytoprotective and antioxidant activity of Hedera helix (HH) and Scrophularia nodosa (SN), two medicinal plants more commonly known as ivy and figwort, against H2O2-induced oxidative stress in mouse primary spleen cells. Thus, the preventive effects of powders of 3 different granulometric classes (50–100 μm, 100–180 μm and 180–315 μm) and those of the hydroethanolic (HE) extract from HH and SN on oxidative stress were compared by monitoring reactive oxygen species (ROS) formation, malondialdehyde (MDA) production, and the activity of enzymatic antioxidants including catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx). Results showed that pretreatment with the 3 fine powders from both plants generally offered to H2O2-exposed spleen cells, a protection against oxidative stress, highlighted by a significant decrease of both ROS formation and the level of MDA ( p < 0.001), and a significant increase of GPx activity ( p < 0.05). The two superfine powders (i.e. 50–100 μm and 100–180 μm), at 250 μg/mL, were more effective in modulating all oxidative stress markers studied than both HE extracts ( p < 0.01), and the powder with the highest particular size (i.e., 180–315 μm) ( p < 0.01). Compared to untreated cells, our results suggest that pretreatment with powders, in particular the superfine fractions, has relatively restored the levels of antioxidant-related enzymes including GPx, CAT and SOD. In summary, our results suggest differential effects between the 3 different fine powders studied, with the best cytoprotective and antioxidant activities being in favor of the superfine powders.

Effect of processing variables on the physico-chemical characteristics and aroma of borş, a traditional beverage derived from wheat bran

Borş is a traditional Romanian beverage obtained by naturally fermenting an aqueous suspension of wheat bran and corn flour, used as flavoring enhancer in local gastronomy since ancient times, and more recently consumed as refreshing drink. To investigate the changes in sensory, physico-chemical, phenolic and aroma composition resulted after two successive fermentations, borș samples were subjected to standard, sensory, HPLC and GC/MS analysis. Total phenolic compounds and ferulic acid, the most abundant phenolic compound, were positively influenced by natural starter addition, increase of fermentation temperature, and thermal treatment, whereas the effect on less abundant phenolic acids was not univocal. The variables had the same effect on antioxidant activity and brown index. Volatiles (alcohols, carboxylic acids, esters), pungent-sour and goat milk-cheese odor notes increased at higher fermentation temperature, whereas bran and yogurt odor notes decreased. The addition of a natural starter at 4 °C allowed balancing odor intensity and antioxidant activity.

Changes in Phenolic Acid Content in Maize during Food Product Processing

The notion that many nutrients and beneficial phytochemicals in maize are lost due to food product processing is common, but this has not been studied in detail for the phenolic acids. Information regarding changes in phenolic acid content throughout processing is highly valuable because some phenolic acids are chemopreventive agents of aging-related diseases. It is unknown when and why these changes in phenolic acid content might occur during processing, whether some maize genotypes might be more resistant to processing induced changes in phenolic acid content than other genotypes, or if processing affects the bioavailability of phenolic acids in maize-based food products. For this study, a laboratory-scale processing protocol was developed and used to process whole maize kernels into toasted cornflakes. High-throughput microscale wet-lab analyses were applied to determine the concentrations of soluble and insoluble-bound phenolic acids in samples of grain, three intermediate processing stages, and toasted cornflakes obtained from 12 ex-PVP maize inbreds and seven hybrids. In the grain, insoluble-bound ferulic acid was the most common phenolic acid, followed by insoluble-bound p-coumaric acid and soluble cinnamic acid, a precursor to the phenolic acids. Notably, the ferulic acid content was approximately 1950 μg/g, more than ten-times the concentration of many fruits and vegetables. Processing reduced the content of the phenolic acids regardless of the genotype. Most changes occurred during dry milling due to the removal of the bran. The concentration of bioavailable soluble ferulic and p-coumaric acid increased negligibly due to thermal stresses. Therefore, the current dry milling based processing techniques used to manufacture many maize-based foods, including breakfast cereals, are not conducive for increasing the content of bioavailable phenolics in processed maize food products. This suggests that while maize is an excellent source of phenolics, alternative or complementary processing methods must be developed before this nutritional resource can be utilized.

Technologies for enhancement of bioactive components and potential health benefits of cereal and cereal-based foods: Research advances and application challenges

Cereal grains are a major source of human food and their production has steadily been increased during the last several decades to meet the demand of our increasing world population. The modernized society and the expansion of the cereal food industry created a need for highly efficient processing technologies, especially flour production. Earlier scientific research efforts have led to the invention of the modern steel roller mill, and the refined flour of wheat has become a basic component in most of cereal-based foods such as breads and pastries because of the unique functionality of wheat protein. On the other hand, epidemiological studies have found that consumption of whole cereal grains was health beneficial. The health benefit of whole cereal grain is attributed to the combined effects of micronutrients, phytochemicals, and dietary fibre, which are mainly located in the outer bran layer and the germ. However, the removal of bran and germ from cereal grains during polishing and milling results in refined flour and food products with lower bioactive compounds and dietary fibre contents than those from whole grain. Also, the level of bioactive compounds in cereal food is influenced by other food preparation procedures such as baking, cooking, extrusion, and puffing. Therefore, food scientists and nutritionists are searching for strategies and processing technologies to enhance the content and bioavailability of nutrients, bioactive compounds, and dietary fibre of cereal foods. The objective of this article was to review the research advances on technologies for the enhancement of bioactive compounds and dietary fibre contents of cereal and cereal-based foods. Bioactivities or biological effects of enhanced cereal and cereal-based foods are presented. Challenges facing the application of the proposed technologies in the food industry are also discussed.

A Comparison of the Chemical Composition, In Vitro Bioaccessibility and Antioxidant Activity of Phenolic Compounds from Rice Bran and Its Dietary Fibres

The composition, in vitro bioaccessibility and antioxidant activities of the phenolic compounds in defatted rice bran (DRB) and its soluble and insoluble dietary fibres were systematically evaluated in this study. The total phenolic content of insoluble dietary fibre from DRB (IDFDRB) was much higher than that of the soluble dietary fibre from DRB (SDFDRB) but was 10% lower than that of DRB. Bound phenolics accounted for more than 90% of the total phenolics in IDFDRB, whereas they accounted for 34.2% and 40.5% of the total phenolics in DRB and SDFDRB, respectively. Additionally, the phenolic profiles and antioxidant activities were significantly different in DRB, SDFDRB and IDFDRB. The phenolic compounds in IDFDRB were much less bioaccessibility than those in DRB and SDFDRB due to the higher proportion of bound phenolics in IDFDRB. Considering that bound phenolics could be released from food matrices by bacterial enzymes in the large intestine and go on to exert significant beneficial health effects in vivo, further studies on IDFDRB are needed to investigate the release of the phenolics from IDFDRB via gut microbiota and the related health benefits.

Extraction methods and food uses of a natural red colorant from dye sorghum

BACKGROUND

The interest in stable natural colorants for food applications continues to grow. A red pigment extracted from the leaf sheaths of a sorghum variety (Sorghum bicolor) with a high content of apigeninidin is widely used as a biocolorant in processed foods in West Africa. This study compared the colour and anthocyanin composition from traditional extraction methods to determine options for improvement and use of the red biocolorant from dye sorghum in the food sector.

RESULTS

Sorghum biocolorant was commonly applied in fermented and heated foods. Traditional extraction methods predominantly differed in two aspects, namely the use of an alkaline rock salt (locally known as kanwu) and the temperature of the extraction water. Cool extraction using the alkaline ingredient was more efficient than hot alkaline and hot aqueous extractions in extracting anthocyanins. The apigeninidin content was three times higher in the cool and hot alkaline extracts than in the aqueous extract.

CONCLUSION

Cool and hot alkaline extractions at pH 8-9 were the most efficient methods for extracting apigeninidin from dye sorghum leaf sheaths. Broader use of the sorghum biocolorant in foods requires further research on its effects on nutrient bioavailability and antioxidant activity. © 2017 Society of Chemical Industry.

Bioactive compounds and antioxidant capacity of extruded snack-type products developed from novel formulations of lentil and nutritional yeast flours

Pulses are well known to be gluten-free functional foods that provide a rich source of nutritional and healthy compounds with antioxidant-promoting activity.

Relevance, structure and analysis of ferulic acid in maize cell walls

Phenolic compounds in foods have been widely studied due to their health benefits. In cereals, phenolic compounds are extensively linked to cell wall polysaccharides, mainly arabinoxylans, which cross-link with each other and with other cell wall components. In maize, ferulic acid is the phenolic acid present in the highest concentration, forming ferulic acid dehydrodimers, trimers and tetramers. The cross-linking of polysaccharides is important for the cell wall structure and growth, and may protect against pathogen invasion. In addition to the importance for maize physiology, ferulic acid has been recognized as an important chemical structure with a wide range of health benefits when consumed in a diet rich in fibre. This review paper presents the different ways ferulic acid can be present in maize, the importance of ferulic acid derivatives and the methodologies that can be used for their analysis.

Food processing strategies to enhance phenolic compounds bioaccessibility and bioavailability in plant-based foods

Phenolic compounds are important constituents of plant-based foods, as their presence is related to protective effects on health. To exert their biological activity, phenolic compounds must be released from the matrix during digestion in an absorbable form (bioaccessible) and finally absorbed and transferred to the bloodstream (bioavailable). Chemical structure and matrix interactions are some food-related factors that hamper phenolic compounds bioaccessibility and bioavailability, and that can be counteracted by food processing. It has been shown that food processing can induce chemical or physical modifications in food that enhance phenolic compounds bioaccessibility and bioavailability. These changes include: (i) chemical modifications into more bioaccessible and bioavailable forms; (ii) cleavage of covalent or hydrogen bonds or hydrophobic forces that attach phenolic compounds to matrix macromolecules; (iii) damaging microstructural barriers such as cell walls that impede the release from the matrix; and (iv) create microstructures that protect phenolic compounds until they are absorbed. Indeed, food processing can produce degradation of phenolic compounds, however, it is possible to counteract it by modulating the operating conditions in favor of increased bioaccessibility and bioavailability. This review compiles the current knowledge on the effects of processing on phenolic compounds bioaccessibility or bioavailability, while suggesting new guidelines in the search of optimal processing conditions as a step forward towards the design of healthier foods.

Effect of Different Extrusion Parameters on Dietary Fiber in Wheat Bran and Rye Bran

Wheat bran and rye bran are mostly used as animal feed today, but their high content of dietary fiber and bioactive components are beneficial to human health. Increased use of bran as food raw material could therefore be desirable. However, bran mainly contains unextractable dietary fiber and deteriorates the sensory properties of products. Processing by extrusion could increase the extractability of dietary fiber and increase the sensory qualities of bran products. Wheat bran and rye bran were therefore extruded at different levels of moisture content, screw speed and temperature, in order to find the optimal setting for increased extractability of dietary fiber and positive sensory properties. A water content of 24% for wheat bran and 30% for rye bran, a screw speed of 400 rpm, and a temperature of 130 °C resulted in the highest extractability of total dietary fiber and arabinoxylan. Arabinoxylan extractability increased from 5.8% in wheat bran to 9.0% in extruded wheat bran at those settings, and from 14.6% to 19.2% for rye bran. Total contents of dietary fiber and arabinoxylan were not affected by extrusion. Content of β-glucan was also maintained during extrusion, while its molecular weight decreased slightly and extractability increased slightly. Extrusion at these settings is therefore a suitable process for increasing the use of wheat bran and rye bran as a food raw material.

Stability of Bioactive Compounds in Broccoli as Affected by Cutting Styles and Storage Time

Broccoli contains bioactive molecules and thus its consumption is related with the prevention of chronic and degenerative diseases. The application of wounding stress to horticultural crops is a common practice, since it is the basis for the fresh-cut produce industry. In this study, the effect of four different cutting styles (CSs) (florets (CS1), florets cut into two even pieces (CS2), florets cut into four even pieces (CS3), and florets processed into chops (CS4)) and storage time (0 and 24 h at 20 °C) on the content of bioactive compounds in broccoli was evaluated. Immediately after cutting, 5-O-caffeoylquinic acid and caffeic acid content increased by 122.4% and 41.6% in CS4 and CS2, respectively. Likewise, after storage, 3-O-caffeoylquinic acid and 5-O-caffeoylquinic acid increased by 46.7% and 98.2%, respectively in CS1. Glucoerucin and gluconasturtiin content decreased by 62% and 50%, respectively in CS3; whereas after storage most glucosinolates increased in CS1. Total isothiocyanates, increased by 133% immediately in CS4, and after storage CS1 showed 65% higher levels of sulforaphane. Total ascorbic acid increased 35% after cutting in CS2, and remained stable after storage. Results presented herein would allow broccoli producers to select proper cutting styles that preserve or increase the content of bioactive molecules.