Free Phenolic Acids Research Articles

Changes in the free phenolic acid composition of pepper (Capsicum annuum L.) leaves in response to green peach aphid (Myzus persicae Sulzer) infestation

Aphids are considered one of the most damaging pests in agriculture. Plants respond to aphid attack with the production of toxic, repellent and/or antinutritive metabolites, including phenolic compounds. In this study, we examined the free phenolic acid composition of pepper (Capsicum annuum L.) leaves in response to green peach aphid (Myzus persicae Sulzer) feeding in different time course experiments. When plants were infested with an initial low density of aphids (20 aphids/plant), few significant changes were shown in leave phenolic content suggesting a very slight response from plants. However, with a high density of aphids (200 aphids/plant), several phenolics, especially the cinnamic acids (C6-C3): caffeic acid, p-coumaric acid, and sinapic acid, and also the p-hydroxybenzoic acid, salicylic acid, accumulated at specific times. Conversely, another hydroxy-benzoic acid: protocatechuic acid strongly decreased in response to infestation. The possible role of the observed changes in plant defence responses or in aphid counter-defence is discussed.

Phenolics and related in vitro functional activities of different varieties of fresh waxy corn: a whole grain

The polyphenol distribution in fresh waxy corns of different color varieties and their functional activities, which may be useful for treating various chronic diseases, were investigated. The in vitro antioxidant activity, and hypoglycemic and hypocholesterolemic effects of the free and bound corn phenolics were determined to evaluate the edible value of fresh waxy corn. The colored varieties contained more phenols than the common varieties (white and/or yellow). The total free phenolic acid content of the six varieties was 6637.73 µg/g DW (dry weight), which was slightly higher (P > 0.05) than that of the total bound form (6276.65 µg/g DW). The total free flavonoid content was 5850.09 µg/g DW, which was higher (P < 0.05) than that of the total bound form (4874.51µg/g DW). No bound anthocyanin was detected in the methanol extracts of the tested varieties. For all the varieties, free polyphenols contributed 86−100 % and 70−78 % of the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging abilities, respectively, and 100 % of the ferric reducing capacity. The free phenolics in fresh waxy corn showed better (P < 0.05) hypoglycemic effect than the bound form in terms of inhibition of α-amylase activity, whereas the bound phenolics of most varieties showed higher α-glucosidase inhibitory activity than the free forms. The free phenolics showed better (P < 0.05) glycocholesterol binding than the bound form for all varieties. The bound polyphenols showed better sodium cholate and taurocholate binding than the free form for most varieties. In conclusion, the difference between free and bound polyphenol content and functional activities indicates that fresh waxy corn can be potentially used for the development of functional food.

The Impact of Formulation on the Content of Phenolic Compounds in Snacks Enriched with Dracocephalum moldavica L. Seeds: Introduction to Receiving a New Functional Food Product.

A new type of multigrain snack has been designed containing varied additions of Moldavian dragonhead (Dracocephalum moldavica L.) seeds. The antioxidant properties and the general health benefits of this plant material have already been widely acknowledged. The research discussed herein aimed to investigate the influence of the formulation and expansion method (frying) on the content of polyphenolic compounds, individual phenolic acids, and antiradical properties of innovative snacks enriched with dragonhead seeds. The highest content of polyphenols (0.685 mg GAE/mL), free phenolic acids (47.052 µg/g of dry matter), and highest radical scavenging activity (96.23% towards DPPH) were found in the fried snacks enriched with 22% of seeds. In these samples, 11 phenolic acids were detected. Strong positive correlations were seen between the addition of dragonhead and the polyphenol content (r = 0.989) and between the quantity of the enriching additive and the content of free phenolic acids (r = 0.953). The research has shown that such innovative snacks have the potential to supply health-benefiting free phenolic acids, e.g., salicylic, isoferulic, ferulic, p-coumaric, vanillic. Our studies provide an introduction to the development of a new range of functional foods.

Antioxidant activities, tyrosinase inhibition activity and bioactive compounds content of broken rice fermented with Amylomyces rouxii

Solid state fermentation (SSF) utilizing filamentous fungus Amylomyces rouxii was investigated as a bio-processing strategy to enhance the bioactive properties of broken rice. Fermentation was carried out for 18 days and samples were withdrawn at 2-days interval. Established methods were deployed to assess the changes in bioactive properties and compounds content in fermented broken rice. The bioactive properties studied were total phenolic content (TPC), total flavonoid content (TFC), DPPH-radical scavenging activity and ferric-reducing antioxidant power (FRAP). Additionally, tyrosinase inhibition activity, which represents anti-pigmentation/browning property, was evaluated. Free phenolic acids and organic acids content were determined through high performance liquid chromatography (HPLC). The results showed that fermentation significantly increased the total phenolic content of broken rice from 0.03 mg GAE/g sample to 3.94 mg GAE/g sample and total flavonoid content from 0.04 to 1.71 mg QE/g sample. By the end of the fermentation, DPPH-radical scavenging of fermented broken rice was enhanced to 94.22%, compared to 9.03% in the unfermented sample. It was also observed that FRAP and tyrosinase inhibition activity of fermented broken rice were improved up to 39- fold and 50-fold, respectively. Kojic acid, a potent antioxidant and tyrosinase inhibitor, was detected in fermented broken rice, along with oxalic and ascorbic acid. Gallic, protocatechuic and 4-hydroxybenzoic acids were enhanced upon fermentation. This study manifested the positive effect of broken rice after fermentation with A. rouxii and thus revealed the potential of fermented broken rice as a promising natural bio-ingredients in food, cosmetics and medicinal products.

The Composition of Free Amino Acids and Phenolic Acids in Lac Pigment Extracts, and Physiological Activity of Cosmetics

The Composition of Free Amino Acids and Phenolic Acids in Lac Pigment Extracts, and Physiological Activity of Cosmetics

Agronomic performance and phenolic profile of Tritordeum (x Tritordeum martinii A. Pujadas) lines

AbstractBackground and objectivesTritordeum, a cereal obtained by crossing a durum wheat and a wild barley, has attracted interest for its suitability as a functional food crop, but the phenolic compounds present in the grain and the agronomic effect of crop year on levels of phenolics have yet to be elucidated. The objective of the present three‐year study was to analyze the agronomic aspects and phenolic acid content of five Tritordeum lines grown in Southern Italy.FindingsAgronomical results showed the good potential of this cereal that can be considered a promising species for this environment, highlighting that at present the Tritordeum JB1, HT444, and HT621 resulted in higher values than durum wheat for most of the grain parameters (harvest index, height of plant, test weight, 1,000‐kernel weight, and protein content) and phenolic content (gallic, p‐hydroxybenzoic, chlorogenic, and gentisic). Despite until recent days limited information is available about the concentration and the composition of phenolic acids in Tritordeum, twelve phenolic acids were identified across the genotypes.ConclusionsTritordeum showed a relevant concentration of free phenolic acids and in particular HT621 contains the highest amounts of ferulic and sinapic acids. Moreover, cinnamic and gentisic acids have been reported in Tritordeum grain for the first time, being reported only in other cereals.Significance and noveltyTo our knowledge, no other studies have reported as complete a phenolic profile of the species. Tritordeum has good potential for the production of food products rich in phenolic compounds.

Study of continuous flow ultrasonication to improve total phenolic content and antioxidant activity in sorghum flour and its comparison with batch ultrasonication

Ultrasonic technology was applied to release the phenolics bound with starch and protein matrix in order to enhance total phenolic content (TPC) and antioxidant activity (AA) of the sorghum flour. Both the continuous flow and batch ultrasonication were implied with independent variables such as flour to water ratio (FWR), ultrasonication intensity (UI), and ultrasonication time (UT) with an additional variable as flow rate (FR) in continuous flow ultrasonication. All the process variables showed a significant effect on the corresponding ultrasonication process. The optimal conditions for the continuous flow ultrasonication were a FWR of 10% w/v, an UI of 20 W/cm2, an UT of 130 s, and 15 ml/s FR which produced a maximum values of 70.9 mg GAE/100 g dry matter (d.m.) for TPC and 143.9 µmol TE/100 g d.m. for AA. Regarding the batch ultrasonication, the maximum values were 65.6 mg GAE/100 g d.m. and 141.0 µmol TE/100 g d.m. for TPC and AA, respectively at optimum conditions of 10% w/v FWR, 30 W/cm2 UI, and 200 s UT. When comparing with the batch ultrasonication, the continuous flow process saved 35% time and 33% of energy consumption to obtain comparatively higher TPC and AA of the sorghum flour. Ultrasonication improved free phenolic acid content by releasing bound phenolics in the sorghum flour. Impact of various process parameters on specific energy was analyzed during both the processes, and influence of energy on TPC and AA of the sorghum flour was also observed for the batch and continuous flow ultrasonication.

Alterations of phenolic compounds in red raspberry juice induced by high-hydrostatic-pressure and high-temperature short-time processing

Most studies on health-promoting attributes of red raspberries have been conducted using extracts or freeze-dried powders instead of commercially processed products. This work aimed to trace the alterations of phenolic compounds in HHP- and HTST-treated juices. In total, 151 phenolic compounds were identified: 13 and 26 differential phenolics were discriminated in HHP- and HTST-treated juices, respectively. The alterations of phenolic compounds could be related to the increased oxidative stress derived from the indirect oxidation and thermal degradation. HTST processing promoted the release of free phenolic acids from their conjugated forms, while HHP processing could maximize the flavonol glycosides. Furthermore, morin was observed with a 7400-fold increase in HTST-treated juice, indicating the potential use for juice authenticity. Generally, HHP processing showed less impact on phenolic profiles in comparison with HTST processing. These findings provide novel insights into the impacts of sterilization processes on phenolic compounds in red raspberries.

The Role of Endogenous Enzymes during Malting of Barley and Wheat Varieties in the Mitigation of Styrene in Wheat Beer.

Knowledge of the biochemical processes responsible for the release of phenolic acids (precursors of vinyl aromatics) during malting is important to find mitigation strategies for the toxicologically relevant styrene (formed from cinnamic acid) in wheat beer. Therefore, grain and malts of four barley and three wheat varieties were screened for the activities of various enzymes and the amounts of nonstarch polysaccharides (to which the phenolic acids are bound to a certain extent). During malting, a very strong degradation of β-glucan, synonymous to a depletion of the cell walls, was found, suggesting that a partial degradation of cell walls cannot have an effect on the release of phenolic acids. In barley malts, water-extractable arabinoxylan contents were between 0.59 and 0.79 g/100 g dm and in wheat malts between 0.93 and 1.51 g/100 g dm. Additionally, higher soluble ferulic acid contents in wheat wort compared to barley wort indicated that the degradation of nonstarch polysaccharides has an impact on the release of phenolic acids. For the feruloyl esterase, higher activities were found in malts of the barley varieties. However, this fact was not reflected by the free phenolic acid contents in those malts. Correlation coefficients between the protease activity and the feruloyl esterase, α- and β-amylase, and β-glucanase activities were proven to be insignificant, highlighting that the protease activity had no effect on the activities of these other enzymes.

Polyphenol Composition and Antioxidant Potential of Instant Gruels Enriched with Lycium barbarum L. Fruit.

Goji fruit (Lycium barbarum L.) has been identified as a polyphenolic compound plant source of noted richness. It also contains polysaccharides, carotenoids, vitamins and minerals, fatty and organic acids. The purpose of the presented research was to produce innovative instant corn gruels with various dry goji berry contents (1, 3 and 5%), to determine the level of included polyphenolic compounds (including individual free phenolic acids) and to assess the antioxidant properties of these functional-food products. A further objective was to identify the optimum value of one of the most important production parameter, the rotational speed of the extruder’s screw during gruel processing. The undertaken chromatographic analysis (LC-ESI-MS/MS) showed a wide variety of available phenolic acids. In the samples with 5% addition of fruit, eight phenolic acids were detected, whereas in the corn gruel without additives, only five were noted. The antioxidant activity, the content of free phenolic acids and the sum of polyphenols increased with increase of the functional additive. For all goji content, screw speeds of 100 and 120 rpm rather than 80 rpm resulted in higher polyphenol amounts and greater Trolox equivalent antioxidant capacity, as well as higher ability to scavenge DPPH.

Influence of Thermal Processing on Free and Bound Forms of Phenolics and Antioxidant Capacity of Rice Hull (Oryza sativa L.).

The objective of this study was to evaluate the effects of heat treatment on the phenolics and antioxidant activity of rice hull. Heat treatment was performed at temperatures 80∼140°C for 1∼5 h, and the heated rice hull was extracted with 80% (v/v) methanol in an ultrasonic bath. The highest total polyphenol and flavonoid content (10.68 mg gallic acid equivalents/g and 1.83 mg catechin equivalents/g, respectively) occurred in rice hull heated at 130°C for 5 h. During heat treatment, the content of free phenolic acids increased compared with that of the bound phenolic acids. The highest 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity and reducing power was observed in rice hull heated at 140°C for 3 h. The highest OH radical scavenging activity was 75.30% in rice hull heated at 140°C for 5 h. These results suggested that heat treatment was an efficient method to enhance the antioxidant characteristics of rice hull.

Antioxidant properties of free and bound phenolic acids from bran, spent grain, and sorghum seeds

AbstractBackground and objectiveSorghum by‐products contain important amount of phenolic compounds and may be used as sources of phenolic antioxidants. This study aims to investigate the phenolic contents and the antioxidant activities of free and bound phenolic extracts from sorghum bran, spent grain, and seeds as potential sources of natural antioxidants agents.FindingsAmong the six extracts, the free phenolic acids (PA) mixture from bran with the highest total phenolic contents (291.50 ferulic acid equivalents/g flour) showed the highest antioxidant activity with all three tests (FRAP, ABTS, and DPPH). Syringic (0.06–2.65 mg/100 g of flour), vanilic (0.47–2.63 mg/100 g), and p‐hydroxybenzoic (0.38–1.75 mg/100 g) acids were the major free PAs. Ferulic acid (1.20–6.37 mg/100 g) was the major bound PA. PA content and composition in the mixtures greatly contribute to their antioxidant activity.ConclusionsFree and bound PA from sorghum by‐products, especially the free PA from bran, have significant antioxidant and free radical scavenging activities. These could be potentially used as important sources of natural antioxidants.Significance and noveltyThis finding encourages the exploration of sorghum by‐products (bran and spent grain) in the production of natural phenolic antioxidants for functional food preparations.

Nutritional value and antioxidant activity of Chinese black truffle (Tuber indicum) grown in different geographical regions in China

Nutritional and health-promoting properties of Tuber indicum are still unclear. In this study, total phenol content (TPC) and total flavonoid contents (TFC) were determined by colorimetric methods; free phenolic acids, vitamin D2 and ergosterol content were determined by HPLC; antioxidant activity were evaluated using ABTS, DPPH, and FRAP assays; in vitro anti-inflammatory activity was evaluated by protease inhibitory assay. Our results indicated that geographical origin exhibits a significant impact on the nutritional and pharmaceutical properties of Tuber indicum. The samples collected from Sichuan present significant higher proteins (23.2 g/100 g dw), ash (6.38 g/100 g dw), 1,3:1,6-β-glucan (14.7 g/100 g dw) and ergosterol content (0.76 mg/g dw); whereas the samples collected from Yunnan present the highest amount of pectin (4.52 g/100 g dw), food energy (345.20 kcal/100 g dw), TPC (1.53 mg GAE/g dw), TFC (1.66 mg CAE/g dw) and the highest ABTS and DPPH values, and potent anti-inflammatory effects. In addition, the samples collected from Jilin presented the highest amount of total carbohydrate (51.7 g/100 g dw), reducing sugar (7.3 g/100 g dw) and total phenolic acids (66.76 μg/g dw). These results will enhance current knowledge about nutritional values, chemical compositions, and biological properties of T. indicum.

Phytochemical profiles, antioxidant, and antiproliferative activities of red-fleshed apple as affected by in vitro digestion.

The aim of this study was to characterize the phenolic profiles in the extracts and digesta (after in vitro digestion) of different red-fleshed apple fruit parts and to assess the effects of digestion on the in vitro antioxidant capacity and antiproliferative activity. The main polyphenols were identified by UPLC-MS/MS and HPLC. Our results indicate that the digesta had less total phenolics, flavonoids, and anthocyanins, but more free phenolic acids, than the extracts. An analysis of the in vitro antioxidant capacity (including ABTS radical scavenging activity, DPPH radical-scavenging capacity, ferric reducing antioxidant power [FRAP], and cellular antioxidant activity [CAA]) revealed that the digestion decreased the ABTS, DPPH, and FRAP values, but increased the CAA values, relative to the corresponding values for extracts. These results suggest that the digestion improved the effectiveness of the phenolic substances. Moreover, our findings imply that the digestion promoted the antiproliferative activity of red-fleshed apple peels and flesh relative to the extracts. Future in vivo investigations are warranted based on the results of the current study. PRACTICAL APPLICATION: The effects of an in vitro digestion on the phenolic compounds as well as the antioxidative and antiproliferative activities of red-fleshed apple were evaluated. The resulting data may clarify the bioavailability of the polyphenols in red-fleshed apple and enable scientists and consumers to exploit natural polyphenols.

Composition and Contents of Free Amino Acids and Phenolic Acid and Flavonoids of Imperata cylindrica Beauvois var. koenigii Root extracts

Composition and Contents of Free Amino Acids and Phenolic Acid and Flavonoids of Imperata cylindrica Beauvois var. koenigii Root extracts

Fermentation of Wheat Bran and Whey Permeate by Mono-Cultures of Lacticaseibacillus rhamnosus Strains and Co-culture With Yeast Enhances Bioactive Properties.

The aim of this work was to obtain a bioingredient (BI) with bioactive properties through the solid fermentation of a wheat bran-whey permeate (WB/WP) mixture with three strains of Lacticaseibacillus rhamnosus (R0011, ATCC 9595, and RW-9595M) in mono or co-culture with Saccharomyces cerevisiae. The choice of these strains was based on their capacity to produce the same exopolysaccharide (EPS), but at different yields. The solid fermentation of WB/WP revealed a similar growth pattern, sugar utilization and metabolite production between strains and types of culture. Lactic acid, soluble protein, free amino acid and phenolic compound content in BI were compared to NFWB. Water soluble polysaccharides (including EPS) were significantly increased in co-culture for (44%) ATCC 9595, (40%) R0011 and (27%) RW-9595M. The amount of bound Total Phenolic Content (TPC) as well as the antioxidant activity in BI were higher after fermentation. The free phenolic acid content was higher after fermentation with ATCC 9595 (53–59%), RW-9595M (45–46%), and R0011 (29–39%) compared to non-fermented NFWB. Fermentation by these strains increased the amounts of free caffeic acid and 4-hydroxybenzoic acid in both types of culture. The bound phenolic acid content was enhanced in co-culture for the BI obtained from the highest EPS producer strain RW-9595M which was 30% higher than NFWB. After in vitro digestion, bioaccessibility of free total phenolic acids was improved by more than 40% in BI compared to NFWB. The co-culture increased recovery of TPC (%) and antioxidant activity compared to monoculture for the strains in digested product. In contrast, the recovery of bound total phenolic acids in co-culture was 33 and 38% lower when compared to monoculture for R0011 and RW-9595M. Our findings provide new insights into the impact of LAB/yeast co-culture on the bioactive properties of fermented wheat bran.

Composition of Phenolic Acids and Antioxidant Properties of Selected Pulses Cooked with Different Heating Conditions.

Pulses are recommended for healthy eating due to their high content of nutrients and bioactive compounds that can undergo changes during cooking. This study investigated the effects of four cooking methods (boiling, pressure, microwave, slow) and three heating solutions (water, salt, sugar) on the phenolic acids and antioxidant properties of three pulses (faba beans, lentils, peas). The composition of phenolic acids differed among the three pulses with p-coumaric and ferulic being the dominant acids. Cooking increased free phenolic acids and lessened bound phenolic acids in faba beans and peas, while decreased both free and bound phenolic acids in lentils. Cooking resulted in reductions in total phenol content (TPC) in faba bean methanol and bound extracts. Pressure and microwave cooking increased TPC in lentil methanol extracts, while pot boiling and slow cooking reduced TPC. Microwave cooking resulted in increases in TPC in bound phenolic extracts from lentils. For peas, cooking increased TPC in both methanol and bound phenolic extracts. Significant changes were also observed in the antioxidant capacity of cooked pulses based on the scavenging ability of DPPH, ABTS and peroxyl radicals subject to the type of pulse, polyphenol and antioxidant assay. Despite the significant reduction in antioxidants, high amounts of phenolics with potent antioxidant activities are still found in cooked pulses.

The effect of storage conditions on the carotenoid and phenolic acid contents of selected apple cultivars

The present study investigated how different storage conditions affect antioxidant levels in three scab-resistant and powdery mildew-tolerant apple cultivars. The contents of carotenoids, along with free and glycosylated phenolic acids, were quantified in harvested apples and apples stored in boxes with controlled atmospheric conditions (1.2% O2 and 2.2% CO2) and temperature (1 °C), boxes with regulated temperature (1 °C) and storage rooms with a temperature between 1 and 4 °C. All three cultivars demonstrated a continuous decrease in total carotenoid content (sum of s-carotene, lutein, neoxanthin, violaxanthin, zeaxanthin and antheraxanthin) during the storage period. However, apples stored under controlled atmospheric conditions showed significantly higher carotenoid levels than apples stored under other approaches over 3 and 5 months of storage. Although the storage approach clearly affected carotenoid levels across the three tested cultivars, the ratio between the levels of individual carotenoids was neither affected by storage approach nor cultivar. Free phenolic acid contents were found to be cultivar specific; whereas, all three cultivars demonstrated similar glycosylated phenolic acid contents. Chlorogenic acid was the most common free phenolic acid in all three cultivars, while protocatechuic and caffeic acid were the dominant glycosylated phenolic acids identified from the cultivars. Interestingly, stored apples showed higher free phenolic acid levels than harvested apples; while, both harvested and stored apples showed similar concentrations of glycosylated phenolic acids. As such, none of the three tested storage conditions had a pronounced effect on either group of phenolic acids (total content or concentrations of individual compounds).

Effects of baking on γ‐aminobutyric acid and free phenolic acids from gluten‐free cookies made with native and malted whole sorghum flours

Optimal cookies formulation was determined by conducting an experimental design and used to make gluten-free products with native and malted, white and red sorghum flours. Cookies were evaluated regarding physicochemical, sensory, nutritional, and bio-functional properties. The cooking effect was determined by comparing the content of bioactive compounds before and after baking. Cookies based on malted sorghum flours showed higher protein digestibility (42% vs. 38%), chemical score (98% for malted red sorghum cookies), and bio-functional components (GABA and free phenolic acids) than those made with native sorghum flours. Moreover, the cooking process increased the extractability of phenolic acids and maintained a high level of GABA. White and red sorghum flours could be a potential biofunctional gluten-free ingredient, with high bakery, sensory, and bio-functional attributes. Moreover, cookies could be a good vehicle for bioactive compounds since the mild heat treatment used for baking. Practical applications The increased demand for functional foods and new foods suitable for the celiac population by consumers creates a challenge for food scientists and technologists. Even though scientists often study different bioactive compounds and healthy food ingredients, most of the studies do not cover the effects of cooking on these bioactive compounds in specific foods, which involve different conditions of humidity, temperatures and times. In this sense, native and malted whole sorghum flours are an interesting alternative of whole grain-gluten-free ingredients. Cookies made with these ingredients showed good sensory and cooking characteristics, as well as a high content of bioactive compounds. Moreover, the cooking process increased the bioactive potential. Thus, cookies made with white and red sorghum flours could be a very good vehicle for these compounds. This work could be used by the food industry to obtain new gluten-free products with biofunctional properties.

Characterization of free and insoluble-bound phenolics of chia (Salvia hispanica L.) seeds

The content, antioxidant activity and composition of free and bound phenolics from chia seeds were investigated. The free phenolics were extracted by using ethanol and methanol of analytical purity, 70% v/v ethanol and by 70% v/v methanol. The bound phenolics were extracted from seeds after alkaline hydrolysis was done. The phenolics content obtained by aqueous-alcoholic solutions was higher than the content obtained by using the pure alcoholic solution (for 20.8% by 70% methanol and 41.2% by 70% ethanol). The content of bound phenolics was 932 μg g−1. Among the identified phenolic compounds the apigenin 4'-O-glucoside was the most abundant, and among the acids, a rosmarinic was the most abundant in free phenolic extract and caffeic acid in bound. The correlation coefficients indicated the DPPH method and reducing power were more suitable for assessing the antioxidant activity than the FRAP method.