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The purpose of this paper is to determine the antioxidant properties and phenol content of methanolic extracts of six white varieties and six purple/brown varieties of Indian rice and to find some relationship between the antioxidant properties, phenolic content in the varieties analyzed.

Methanolic extracts of different rice varieties were analyzed for their superoxide radical scavenging activity, 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging activity, total antioxidant capacity, reducing power and ferrous ion chelating properties. The extracts were analyzed for determination of total phenol content, anthocyanin content, oryzanol content. Phenolic acids were determined by HPLC.

All the rice varieties (white and purple/brown) showed activity in a dose‐dependent manner. Free phenolic acids, e.g. protocatechuic acid, caffeic acid, vanillic acid, p‐coumaric acid (PCA), ferulic acid and sinapic acid and the phenolic aldehyde vanillin could be detected in all the rice samples analyzed. No relationship could be established between activity and metabolite content. Principal component analysis and classification shows that superoxide radical scavenging activity, total phenolic acid, protocatechuic acid and ferulic acid are the components to differentiate the varieties from each other.

Little work has been done on the antioxidant activity of white rice. The authors report superoxide radical scavenging activity, DPPH radical scavenging activity, total antioxidant activity, reducing power and ferrous ion chelating properties and phenolic contents of six white varieties and six purple/brown varieties of Indian rice. Free phenolic acids like protocatechuic acid, caffeic acid, vanillic acid, PCA, ferulic acid and sinapic acid are reported from all the 12 varieties of rice.

Tea contains high content of phenolics which are well-known to act as antioxidants. As such, there are claims that the consumption of infusion of tea could help ameliorate free radical-induced diseases; this therapeutic activity would depend on the amount of phenolics that is soluble and the amount that is absorbed and available for metabolic activity when consumed. The purpose of this study is to analyze the content of phenolics and antioxidant activity of some health tea and also to study the effect of addition of sugar and milk on in-vitro availability of phenolics in tea, cocoa and coffee drinks.

Seven brands of health tea, two brands of cocoa drink, one brand each of coffee, powdered milk and sugar were selected. The tea samples were analyzed for pH, titratable acidity, total phenol and antioxidant activity using Folin–Ciocalteau and 202-diphenyl-1-picryl-hydrazil 28DPPH-29-20 reagents. In-vitro simulated digestion modeling stomach and small intestine were carried out on tea infusion, coffee and cocoa drinks with or without sugar, and phenolic availability was analyzed.

The result indicated that pH, titratable acidity and total phenolics ranged from 4.5 to 5.6, 0.167 to 0.837 (as maleic acid) and 1.15 to 1.17 mg/g gallic acid equivalent, respectively. Black tea recorded the highest phenolic content, in-vitro phenolic availability and antioxidant activity. Addition of sugar to black tea and chocolate drink caused a significant decrease in the in-vitro available phenolics, while the addition of milk leads to a significant enhancement.

The data obtained in this study can be used nutritionally and commercially to show the impact of adding sugar or milk on the content of phenolics and their bioavailability in-vitro. The study justifies the claim that tea could help ameliorate free radical-induced health defects.

Assessment of antioxidant activity of food should not be based only on the content of total phenolics but on the amount that is bioavailable in the body system when the food is consumed.

Consumption of tea, cocoa and coffee drinks with milk and sugar have been found to enhance or inhibit phenolics. Therefore, the optimum level of these additives should be determined if the drinks were meant for therapeutic purposes.

Results obtained may provide some useful information for considering the bioavailability of phenolics present in tea and beverages in view of consumption/digestion in our body as well as interference of sugar and milk as the additives.

The purpose of this paper is to evaluate the antioxidant and type II diabetes related enzyme inhibition properties of phenolic extract from raw and traditionally processed Indian under‐utilized food legume grains, Bauhinia purpurea L. (purple camel's foot seeds).

The methanolic extract was prepared from the raw and traditionally processed seed samples and analyzed for total phenolic content. The antioxidant activity and type II diabetes related enzyme inhibition properties of methanolic extract and their relationship with phenolic content was demonstrated.

The methanolic extract of raw seed materials contained total free phenolic content of 14.45±1.62 g catechin equivalent/100 g extract DM. Encouraging levels of ferric reducing/antioxidant power (FRAP, 1203 mmol Fe[II]/mg extract), inhibition of ß‐carotene degradation (45.37 percent) and scavenging activity against DPPH (63.60 percent) and superoxide (42.14 percent) radicals were exhibited by the raw samples. Further, it also recorded 80.69 percent of α‐amylase and 63.74 percent of α‐glucosidase enzyme inhibition characteristics under in vitro starch digestion bioassay. Sprouting+oil‐frying caused an apparent increase on the total free phenolic content, antioxidant and free radical scavenging capacity, while soaking+cooking as well as open‐pan roasting treatments show diminishing effects.

Identification of suitable processing technique offered a good strategy to improve the phenolic content and health relevant functionality of B. purpurea seeds, which could be envisaged as a dietary ingredient in the formulation of supplementary foods with therapeutic value to manage type II diabetic patients.

Bambara groundnut is a hard-to-cook grain and this has limited its utilisation to some extent. However, the grain is a good source of phytochemicals with antioxidant properties. This study investigated the total phenol content, antioxidant, anti-inflammatory and anti-microbial potentials of hot-water extract of four Bambara groundnuts differentiated by their seed coats (cream, black, maroon and brown).

Bambara grains were heated in water at a ratio 1:20 (w/v) and the grains brought to boiling in a controlled water bath. As soon as boiling started, the temperature was reduced to 90 °C to reduce the evaporation rate. The extracts were withdrawn within 30 min, which was chosen from a preliminary study where beyond this time, the extract was drying off and the amount of solution obtained was not sufficient for the initial run. Grain colour and composition and antioxidant, antimicrobial and anti-inflammatory properties of the extract were determined using standard methods.

Protein (20.57–26.31%) and carbohydrate (55.43–61.09%) were the major components of the grain. Grain type and boiling time generally affected the total phenolic content of the extract. Cream Bambara displayed substantially lower total phenolic content at all boiling times compared with the maroon, brown and black Bambara groundnuts. The total flavonoid contents and total phenolic contents of the Bambara groundnut extracts were dependent on the boiling time and type of grain. The extracts showed no activity against Candida albicans, but the maroon coat Bambara demonstrated a peak inhibition of 6.00 mm against Escherichia coli. The total phenolic, flavonoid contents and the antioxidant properties of the grains generally followed the order Maroon > Black > Brown.

This study has demonstrated the possibility of promoting the use of Bambara groundnut beyond the current level of usage by using simple processing method of boiling to extract phytochemicals with medicinal properties.

Salak (Salacca zalacca) is a species of palm tree native to Malaysia and Indonesia. The fruit is also known as “snake fruit” due to its reddish‐brown scaly skin. Four different varieties of the fruits (i.e. SS1, SS2, SS3 and SS4) have been established by Sabah State Agriculture Department, Malaysia. The purpose of this paper is to investigate and compare the antioxidant properties and phytochemicals content in the edible portion of the fruits.

Four different varieties of the fruits were collected and analysed for the antioxidant properties (2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assay), total phenolic and total flavonoid contents using spectrophotometry analysis. Ascorbic acid was determined using titration method.

The results showed the total phenolic and flavonoid contents of the samples were in the range of 12.6‐15.0 mg gallic acid equivalent/g and 4.9‐7.1 mg catechin equivalent/g of dry sample, respectively. The antioxidant activities of the extracts (using DPPH assay) were highly correlated with total phenolic and moderately correlated with flavonoid content. The reducing capabilities of the extracts using FRAP assay were moderately correlated with all phytochemicals tested. The results suggested that the phytochemicals and antioxidant activity of salak is mildly affected by variety. The high phytochemicals and antioxidant properties of S. zalacca indicated that the fruit possessed potential health benefits properties.

Salak fruit is now being developed into fruit juice, pickle and other food products. The commercialization of the fruit may be enhanced if more knowledge on its potential health benefits is studied and discovered. The economic and nutraceutical values might increase and will contribute greatly to the local people.

The purpose of this paper is to evaluate the effect of different drying methods on quality attributes of beetroot slices.

Three drying methods (sun, oven and freeze-drying) were applied to dry fresh slices of beetroot cultivar (Beta vulgaris). The chemical composition, minerals, nitrate, betalains, total phenolic, total flavonoid and color were measured for fresh and dried slices.

The chemical composition, minerals, nitrate, bioactive compounds and color were measured for fresh and dried slices. Regardless of the drying method, the results showed that the chemical composition, total energy, minerals and nitrate of the dried slices were significantly (p=0.05) increased compared to that of fresh slices. Sun and oven drying of the slices significantly (p=0.05) reduced total betalain and betacynin. However, betaxanthin was significantly (p=0.05) increased. Total phenolics content of fresh beetroot was significantly (p=0.05) increased after sun and oven drying but total flavonoids were decreased. The 2,2,-diphenyl-2-picryl-hydrazyl (DPPH) of fresh beetroot was increased significantly (p=0.05) after sun and oven drying. The measurement of the color of the powder showed that there is a decrease in lightness (L) depending on the drying method applied. A maximum reduction in lightness was observed in powder of sun-dried slices. The color of the powder obtained from freeze-dried slices was stable compared to other drying methods.

Beetroot is a rich source of nutrients but with short shelf life. Dried beetroot has more keeping quality than the fresh one.

The study uses beetroot as a rich source of nutrients as well as natural antioxidant source. Betalain compounds are preserved in beetroot and a high source of phenolics and flavonoids. Flavonoids are a group of phenolic products of plant metabolism with high antioxidant properties to protect against diseases without side effects.

The purpose of this paper is to provide a comprehensive evaluation of 34 onion genotypes for their antioxidant activity (AOX) content of phenolics, quercetin and pungency to enable selection of the best genotype for later experiments of variety breeding or to be used as a vector in the improvement of well‐established traditional genotype.

A comprehensive screening of 34 onion (red, pink and white) genotypes is carried out in order to determine the variation in phenolics, quercetin and total AOX as potential for breeding for their enhanced levels.

The AOX in red genotype with highest levels of phenolics is roughly three times higher than commercial white genotype. Pungency levels range from 3.12 to 10.48  μmoles pyruvic acid/g. Mean phenolic and quercetin content ranges from 60.1 to 1094.8 mg gallic acid equivalents/kg and 22.0 to 890.5 mg/kg quercetin, respectively. AOX in red genotype (expressed as μmoles trolox/g) ranges from 1.97 to 5.45 and 3.60 to 6.61 in ferric reducing antioxidant power and cupric ion reducing capacity assays, respectively. Selections, Sel‐383, Sel‐397, Sel‐61‐383, and Inbreds, I‐40, I‐80 and Burgundy are potential genotype with high pungency and AOX.

An improvement in breeding effort designed to increase the phenolics, quercetin and total AOX in onions (Allium cepa L.) provides selected material for analysis. Onion genotype and breeding lines with improved AOX are identified that would help breeders produce onions high in health promoting compounds.

The paper attempts to examine onion genotypes using standardized in‐vitro AOX assays.

Urban beekeeping is spreading as an answer to promote bee conservation and to develop local economies. This study aims to highlight nutritional properties of polyfloral honeys produced in urban landscape and to compare them to the countryside counterparts.

This research has examined polyfloral urban honeys from a restricted area in Central Italy, for antioxidant capacity, total phenolic content and 15 polyphenols profile. Physicochemical parameters have been also determined to assess the overall quality of the samples. Results were compared with polyfloral honeys produced in surrounding countryside and monitored in two harvest years, 2018 and 2019. Principal component analysis was applied to the data to disclose significant differences among honeys and harvest years.

Urban honeys revealed up to threefold higher total amount of polyphenols with respect to rural honeys, and in the 2019 harvest, despite water scarcity that affected the national production, demonstrated 50% higher antioxidant capacity and total phenolic content. The majority of the 15 polyphenols studied resulted in more abundant urban honeys, in particular in the 2019 harvest. The multivariate analysis evidenced how honeys could be successfully separated according to their production area and harvest year by their different polyphenols profile.

Limited data are available on nutritional properties of urban honeys and on their content in antioxidants. The present results suggest that the cultivated urban environment, with its large floral biodiversity, can provide extra nutrition for bees, resulting in the production of a honey rich in nutraceutical compounds.

Flowers and fruits of Madhuca longifolia (Koenig) (mahua) tree are edible and used as traditional Indian medicines. The physicochemical properties of different parts of mahua are investigated. This study aims to estimate the different mineral contents, polyphenols compounds and antioxidant activities by 2,2-diphenyl-1-picrylhydrazyl inhibition, reducing power, free radical scavenging activity using 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) and ferric reducing antioxidant power assays of mahua flower, ripe and unripe fruit.

Flavonoids were identified and quantified in yellow flowers and fruits of M. longifolia tree by high-performance liquid chromatography with diode array detector. Low molecular weight carbohydrates were determined by the ICBio scan, a specific method for determining of carbohydrates. Mineral content is determined by laser-induced breakdown spectroscopy (LIBS) and atomic absorption spectroscopy. Physicochemical, nutritional and mineral properties of mahua flower, ripe and unripe fruit were investigated by the statistical approach of principal component analysis (PCA).

Ascorbic acid, gallic acid (GA), quercetin and myrcetin were the phenolic compounds identified and quantified in mahua flower and fruit extracts. Sugar profiling of mahua flowers and fruits confirmed the presence of inositol, sorbitol, mannitol, dextrose, fructose, sucrose, raffinose and maltose. The mineral content of Na, K, Mg and Ca was present in quite a good amount in all samples. Total phenolic content (TPC) was significantly high in mahua flower (25.3 ± 1.0 mg GA equivalent/g FW) followed by mahua unripe (15.8 ± 1.0 mg GA equivalent/g FW) and ripe fruit (14.3 ± 1.0 mg GA equivalent/g FW) at p = 5%. In contrast, total flavonoid contents (TFCs) were highest in ripe fruit, then mahua flower and unripe fruit. Positive correlations were predicted by PCA for mahua flower with TPC, antioxidant activity assays and minerals except for Na; ripe fruit with TFC and Na; and unripe fruit with maltose and sorbitol.

This study demonstrates the application of LIBS for the determination of elements present in the mahua flowers and fruits and reveals that mahua can be a good source of nutrients. Sugar profiling of mahua flower showed that it is a rich source of reducing and non-reducing sugar, proving that mahua flower juice can be used as a natural sweetener in the development of different food products, namely, biscuits, cookies, cake, jam, jelly, juice and squash.

Literature has consistently reported that coloured plants are rich in dietary bioactive compounds. Therefore, this study aims to compare the total phenolic content and antioxidant activities in selected coloured plants (blue butterfly pea flower, roselle calyx, yellow bell pepper and purple sweet potato).

Total Phenolic Content (TPC) was determined using Folin–Ciocalteu assay, while antioxidant activities were evaluated using 2,2-dophenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging, Ferric Reducing Antioxidant Power (FRAP) and Trolox Equivalent Antioxidant Capacity (TEAC) assays.

TPC was reported from 273.15 ± 19.57 µg GAE/g DW (blue butterfly pea flower extract) to 363.10 ± 7.94 µg GAE/g DW (roselle calyx extract). Antioxidant activities as determined by DPPH assay ranged from 17.26 ± 0.06% (purple sweet potato extract) to 83.38 ± 1.04% (yellow bell pepper extract); while for FRAP assay was 4.92 ± 0.18 mg Fe (II)/g DW (purple sweet potato extract) to 128.33 ± 11.59 mg Fe (II)/g DW (roselle calyx extract). On the other hand, TEAC values were in the range of 15.26 ± 2.83 µg Trolox/g DW (roselle calyx extract) to 364.27 ± 7.14 µg Trolox/g DW (blue butterfly pea flower extract). A significant moderate positive correlation was observed between TPC and DPPH (r = 0.562) as well as TPC and FRAP (r = 0.686).

This study was the first to compare the total phenolic content and antioxidant activities in coloured plants. Findings derived from this study can be extended to the formulation of natural food colourants and nutraceuticals.