A novel preparation method for black rice wine (beer, Huangjiu and sweet wine) and its association with a core nutrient-metabolite network.

Aim: Black Lycium barbarum rice wine is a kind of rice wine produced by the co-fermentation of black Chinese wolfberry and glutinous rice. In this study was to evaluate and compared the antioxidant activity and flavor substances of this type of rice wine with others. Methods: Through headspace gas chromatography-ion mobility spectroscopy (HS-GC-IMS), compared the flavor substances of black wolfberry rice wine, black rice wine, and common rice wine. Many components such as anthocyanins, total sugar, total acid, amino acid nitrogen, etc. in black Chinese wolfberry wine was observed. Results: It was found that the content of anthocyanins in black Chinese wolfberry rice wine increased continuously, approached the maximum value at 24 h, and decreased gradually after 24 h. The scavenging rates of •OH, DPPH, and ABTS in black wolfberry rice wine increased continuously after 24 h. The contents of total sugar, total acid, and amino acid nitrogen showed an increasing trend within 24 h and were close to the maximum. the flavor substances of black wolfberry rice wine and black rice wine were similar, but those of black wolfberry rice wine and common rice wine were different. Conclusion: From the perspective of more than 20 flavor substances, except for the fact that individual components such as butyl acetate, ethyl propionate, ethyl 3-methyl butyrate, and hexanol are much higher in black wolfberry rice wine than in black rice wine, the types and concentrations of other flavor substances are relatively similar, while some esters are absent or very low in common rice wine.

Problem: Kavuni is a traditional black rice variety of Tamil Nadu, India it rich in nutritional and therapeutic properties. These traits it is not being cultivated widely, due to long duration, poor tillering and low yielding agronomic characters.
 Objectives: In the study, twenty three breeding rice lines from the cross between black kavuni and Co 50 were investigated for colour values and phytochemical viz., total phenols content (TPC), total flavonoids content (TFC) and total anthocyanin content (TAC).
 Methods: Twenty five rice samples were grouped as black and white rice based on colour of aleuronic layer by visual inspection. The color values expressed as L* (lightness), a* (redness), b* (yellowness), H° (hue) and C (chroma). TPC by the Folin–Ciocalteu method and expressed as milligram of gallic acid equivalent (mg GAE/g) per g. TFC by aluminum chloride method and expressed as mg catechin equivalent (mg CATE) per 100 g. TAC was measured by pH differential method, expressed as mg cyaniding 3-glucoside per 100 g (c3-glucoside/100 g).
 Main results: The black phenotype rice had low value in L*, b*, C, H° and high values in a* than the white color rice. In the black rice group, 145-6 breeding line had darker black aleuronic layer than other black rice. The TPC, TFC and TAC ranged between 0.74 -3.24 mg GAE/g, 12.79 – 82.58 mg CATE/100 g and 0.4-223.76 mg c3-glucoside/100 g, respectively. High level of TPC, TFC and TAC were recorded in black phenotypic rice, where as lower levels in white rice. The maximum amount of TPC and TAC were observed in 145-6 rice line, which on par with parent black kavuni rice. The maximum level TFC was observed in 144-2 rice line than the parent rice kavuni. The TPC, TFC and TAC were negatively correlated with L*, b*, C and H° values and positively correlated with a* values at 0.01 probability level. Among the 23 rice lines, based on TPC, TAC and TFC the superior breeding rice lines were 145-6 and 144-2 respectively. The results showed that dark black grain has higher phytochemicals than white grain.
 Main recommendation: The results indicate provide the opportunities to further increase the nutritional benefits of some food products from black rice in terms of therapeutic properties.

Physiological characteristics of brown rice and black rice were investigated to provide the fundamental information of physiological property of rice and to show the potential of rice as a functional ingredient. Bioactive compounds were extracted from brown and black rices with aqueous solvents like 80% ethanol. Total phenolics, flavonoids and antioxidative capacity of brown and black rices’ extracts were determined. Brown rice showed much higher amount of total phenolics and flavonoid contents as well as antioxidative capacity than those of milled rice indicating that most of bioactive compounds are located in the bran layer. Black rice showed higher total phenolics and flavonoid contents and antioxidative capacity than those of brown rices. The highest antioxidative capacity was obtained from Heugjinju followed by Heugseol, Sinnongheug-chal, Hopum and Samkwang. This result indicated that antioxidative capacity is affected by total phenolics and flavonoid contents. Both brown and black rices contained higher amount of ferulic acid than that of p-coumaric acid.

Uncovering the flavor differences between black rice wine and glutinous rice wine by GC-MS, GC-IMS, HPLC, and electronic sensory analysis

Total phenolics, flavonoids, antioxidant capacity in rice grain and their relations to grain color, size and weight

Rice with a black-colored pericarp (hereafter, black rice) has attracted considerable attention because of its high nutritional value. It is traditionally grown in infertile agroecosystems, where soil nutrient deficiency would affect grain yield and nutritional quality of the rice. This study examined the effects of phosphorus (P) application (0, 100, 250, 500, 1,000, and 1,300 mg P2O5 pot−1) on the growth, grain yield, and certain quality parameters of unpolished black (“Asamurasaki”) and white (“Takanari”) rice. The results showed that black rice grew poorly under P limitation, resulting in fewer tillers and a lower grain yield, while maintaining higher photosynthetic efficiency than white rice. However, black rice produced under P stress exhibited higher levels of Zn, Fe, and antioxidant (total phenolic and flavonoid content) than white rice, making it more nutritious. The optimal P application rates for black and white rice were 250 and 500 mg P2O5 pot−1, respectively, to achieve high yields. At the optimal rate, black rice exhibited high Fe, Zn and antioxidant levels compared to that at higher P application rates and had lower phytic acid levels, which could alleviate its inhibition of mineral absorption in the digestive tract. Moreover, low grain P due to P stress decreased the lightness L* value in the CIE-Lab system, improving the visual grain quality. Therefore, optimal P management is crucial for maintaining optimal grain yield with low phytic acid concentration and enhancing the nutritional quality of black rice for human consumption.

This study described and evaluated the acidity, alcohol content, total phenolic content, antioxidant activity, and sensory attributes of rice wine (Tapuy) made from black, red, brown and white rice during a 7-day fermentation. Acidity of Tapuy made from the different pigmented rice had similar pH profiles characterized by a steep decrease at day 1 from 6.38 ± 0.4 to 3.38 ± 0.2, and remained relatively unchanged until the end of fermentation. Tapuy made from black rice (Ballatinao) contained 16.07% alcohol, second to white rice (Bongkitan) that contained 18.58% alcohol, although they were not significantly different from each other (p>0.05). At the end of fermentation, the total phenolic content and antioxidant activity of Tapuy made from black rice was significantly higher (p<0.05 and p<0.01, respectively) than Tapuy made from the other pigmented rice. Total phenolic content of Tapuy made from black rice was at 9.73 mg GAE/mL and antioxidant activity leveled-off at 70.63% DPPH radical scavenging activity; whereas Tapuy made from the other pigmented rice were declining. Thus, Ballatinao black rice is a suitable rice variety for making Tapuy and has the potential to be a health-promoting functional food.

This study established a new method for quantitative and qualitative determination of certain components in black rice wine, a traditional Chinese brewed wine. Specifically, we combined solid-phase extraction and high-performance liquid chromatography (HPLC) with triple quadrupole mass spectrometry (MS/MS) to determine 8 phenolic acids, 3 flavonols, and 4 anthocyanins in black rice wine. First, we clean samples with OASIS HLB cartridges and optimized extraction parameters. Next, we performed separation on a SHIM-PACK XR-ODS column (I.D. 3.0 mm × 75 mm, 2.2 μm particle size) with a gradient elution of 50% aqueous acetonitrile (V/V) and water, both containing 0.2% formic acid. We used multiple-reaction monitoring scanning for quantification, with switching electrospray ion source polarity between positive and negative modes in a single chromatographic run. We detected 15 phenolic compounds properly within 38 min under optimized conditions. Limits of detection ranged from 0.008 to 0.030 mg/L, and average recoveries ranged from 60.8 to 103.1% with relative standard deviation ≤8.6%. We validated the method and found it to be sensitive and reliable for quantifying phenolic compounds in rice wine matrices. This study developed a new, reliable HPLC-MS/MS method for simultaneous determination of 15 bioactive components in black rice wine. This method was validated and found to be sensitive and reliable for quantifying phenolic compounds in rice wine.

Cooking can lead to varying degrees of nutrient loss in purple rice. For this investigation, two varieties of purple rice (YZN1 and YZ6) were chosen as the focal points to explore the metabolites associated with rice nutrition post cooking using nontargeted and targeted metabolomics techniques. The results showed that after cooking the two purple rice varieties, the contents of the flavonoids; OPC; TP; total antioxidant capacity; and K, Na, Fe, Mn, Zn, Cu, Ca, and Mg significantly decreased. Compared with YZN1U (YZN1 uncooked), the amino acid and mineral element contents in YZN1C (YZN1 cooked) decreased to varying degrees. After cooking YZ6, the contents of seven amino acids significantly decreased. Following the preparation of purple rice, the metabolites primarily engaged in the pathways of flavonoid synthesis and flavone and flavonol synthesis. Flavonoids, total antioxidant capacity, mineral elements, and amino acids showed a strong correlation with delphinidin and luteolin. The ROC analysis demonstrated that the value of the area under the curve for delphinidin and luteolin was 1 when comparing YZ6C (YZ6 cooked) and YZ6U (YZ6 uncooked), as well as YZN1C and YZN1U. Delphinidin and luteolin can be used as potential biomarkers of nutrient loss after cooking purple rice. This study holds significant implications for the balanced nutrition and healthy development of human dietary grains.

In the present study, polar metabolites including primary metabolites were analysed from red, black and white rice grains using gas chromatography mass spectrometry (GC–MS). Quantitative as well as qualitative differences in metabolite profiles of red, black and white rice were observed. Principal component analysis (PCA) of the data obtained from semi-targeted metabolite profiling showed a clear separation of grains with different pericarp colour. In the PCA scores plot, PC1 separated pigmented rice and non-pigmented rice. While, PC2 separated red rice and black rice. Biplot generated from metabolite profile of the rice grains indicated that vanillic acid, protocatechuic acid and glycerol-3-phosphate differentiate black rice from red and white rice. Erythritol and ribonic acid are present only in red rice causing its separation from black and white rice. Additionally, total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulphonicacid) (ABTS) and the reducing potential of extracts in terms of ferric reducing ability of plasma (FRAP) were carried out. DPPH and ABTS radical scavenging activities of pigmented rice are higher than that of white rice, possibly due to the presence of high TPC in their grains. However, reducing power in terms of FRAP is highest in black rice and is comparable in red and white rice. Furthermore, correlation analysis of antioxidant activities with the metabolites was done to identify the possible primary metabolites contributing to antioxidant capacities of pigmented and non-pigmented rice. This study provides a premise for integration of pigmented rice in our daily diet owing to the potential health benefits of the compositional metabolites.

In the leaf of rice (Oryza sativa L.) cultivar Yunnan purple rice, the anthocyanins with an obvious absorption peak at 530nm were distributed in the cells of upper and lower epidermis, bulliform tissue and bristle. The maximal photosynthetic oxygen evolution rate and chlorophyll content in flag leaves were 28% and 23%, respectively, more than the common green leaf rice cultivar Chijiaoruanzhan. Higher chlorophyll content is probably one of the physiological adaptations for enhancing light harvesting capacity of the antenna in photosystems in this cyanic leaves species. Upon the photooxidation of leaf segments mediated by methyl viologen in weak light for 3 days, the distinct bleaching of anthocyanins in purple rice was associated with the reduction of scavenging ability to DPPH * free radical ability and the increase in membrane leakage rate. But almost no changes in contents of flavonoids and total phenolics were observed. Chlorophyll fluorescence parameters Fv/Fo, qP and phi(PSII) decreased with the increase in NPQ and DES of xanthophylls cycle after photooxidation treatment. Green rice leaves showed more decrease in DPPH * scavenging rate and more increase in cell membrane leakage rate but showed a trace of anthocyanins during photooxidation. It is suggested that anthocyanin may be a beneficial and primary antioxidant in sun cyanic rice leaves against oxidative stress induced by environmental adversity. And photooxidation could induce different changing patterns of anthocyanins between the tested purple and green rice leaves.

SummaryDifferent raw rice and starters will affect the quality of Chinese rice wine (CRW). This study focused on the quality (flavour components, total phenolic content and antioxidant capacity) between Hong Qu japonica rice wine and Wheat Qu glutinous rice wine. Free amino acids and volatile compounds were analysed respectively. Total phenolic content was compared using Folin–Ciocalteu methods and antioxidant activity using DPPH, ABTS+ and FRAP methods. The results indicated that total free amino acid content of CRW ranged from 0.959 ± 0.09 to 3.229 ± 0.24 g L−1. About 65 volatile compounds were obtained in wine samples, mainly including alcohols, esters, aldehydes, acids, phenols and ethers. Isopentanol, isobutanol, phenylethyl alcohol, ethyl lactate, diethyl succinate, benzaldehyde, furfural and 2,4‐ditert‐butylphenol were the prominent aroma components in samples. Total phenolic content in samples ranged from 0.27 ± 0.00 to 0.45 ± 0.01 mg GAE mL−1. Experimental samples showed different radical scavenging capacity and ferric‐reducing capacity. These results proved that japonica rice wine with Hong Qu had abundant flavour components and strongest antioxidant capacity, the brewing raw material can be better developed in the production of CRW.

Antioxidant activity and flavonoid content are important characteristics of colored rice grains. Previously, we obtained a preliminary understanding of the metabolic markers of antioxidant activity, namely, phlorizin and trilobatin, in different colored rice varieties and purple rice grains at different growth stages, but the mechanisms associated with these markers have not yet been confirmed. In this study, purple rice was selected as the experimental material, and clover extract was applied during the grain-filling stage to explore the impact of clover extract on the total antioxidant capacity and flavonoid biosynthesis in purple rice grains. The results indicated that the total flavonoid content, total phenolic content, oligomeric proanthocyanidin content, and total antioxidant capacity of purple rice grains treated with an exogenous application of trilobatin (T30) were significantly greater than those of the control (CK). The flavonoids in the T30 and CK groups accounted for 29.81% of the total flavonoids. The phenylpropanoid biosynthesis and flavonoid biosynthesis metabolic pathways were constructed on the basis of the differentially abundant metabolites between the T30 and CK groups. Additionally, 1-O-sinapoyl-beta-D-glucose, coniferaldehyde, 6″-acetylapiin, and kaempferol-3-O-rutinoside were determined to be essential metabolites for trilobatin-mediated flavonoid biosynthesis in purple rice. The correlation network diagram between biochemical indexes and metabolites revealed that 1-O-sinapoyl-beta-D-glucose, coniferaldehyde, 6″-acetylapiin, and kaempferol-3-O-rutinoside were important metabolites. This study provides a scientific basis for improving the nutritional quality of rice grains and understanding the flavonoid biosynthesis pathway.

Six cultivars of kiwifruits grown in Korea, including Actinidia eriantha ‘Bidan’, A. arguta ‘Chiak’, A. arguta ‘Darae No. 2’, A. chinensis ‘Haegeum’, A. chinensis ‘Haehyang’, and A. arguta × A. deliciosa ‘Mansoo’, were harvested at various maturity stages to test whether kiwifruit maturity has an influence on antioxidant capacity or total phenolic and flavonoid contents. Kiwifruit extracts were isolated using absolute methanol and then 80% (v·v-1) aqueous methanol during homogenization. ‘Bidan’, collected at the second harvest stage, contained the greatest amount of total phenolics (775.3 mg gallic acid equivalents·100 g-1 fresh weight) and had the highest antioxidant capacity [816.5, 633.2, and 2,662.7 mg vitamin C equivalents·100 g-1 fresh weight for 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) scavenging, 1,1-diphenyl-2-picrylhydrazyl scavenging, and oxygen radical absorbance capacity assays, respectively] among cultivars tested, while ‘Haehyang’, collected at the first harvest, contained the greatest amount of total flavonoids (13.1 mg catechin equivalents·100 g-1 fresh weight). Kiwifruit cultivar and genotype influenced antioxidant capacity, as well as total phenolic and flavonoid contents. No trend, however, was observed in total phenolic and flavonoid contents, and in the antioxidant capacity with respect to maturity stage. Antioxidant capacity had a higher linear correlation coefficient with total phenolic contents than with total flavonoid contents. The results above suggest that kiwifruits at various maturity stages are a valuable source of phenolics and antioxidants for industrial application and consumer health benefit.

Rice wines are widely consumed by the general public in Asian countries, while comprehensive studies focused on the individual phenolic compounds in rice wines are limited. A rapid method for simultaneous determination of 13 phenolic compounds in rice wines by high-performance liquid chromatography (HPLC) was developed and validated, and the phenolic compounds in commercial rice wine samples (Chinese rice wine, Japanese sake, and Korean makgeolli) were determined in this paper. The identified compounds contained gallic acid (GA), protocatechuic acid (PRCA), vanillic acid (VA), syringic acid (SRA), caffeic acid (CA), ferulic acid (FA), p-coumaric acid (pCA), sinapic acid (SA), chlorogenic acid (CHA), (+)-catechin (CAT), (−)-epicatechin (EPI), quercetin (QUE), and rutin (RUT). Phenolics were separated with a C18 reversed-phase column at 38 °C by gradient elution using 3 % acetic acid aqueous solution (solvent A) and acetonitrile (solvent B) (0 min, 5 % B; 5 min, 8 % B; 10 min, 15 % B; 20 min, 25 % B; and 25 min, 5 % B) as the mobile phase at 280 nm with flow rate of 1.0 mL min−1. With direct injection of rice wine samples, the chromatograms of all analytes were observed within 20 min, all calibration curves were linear (R 2 > 0.995) within the range, limits of detection (LOD) ranged from 0.02 to 0.06 μg mL−1, and good recoveries (88.07–106.80 %) and precision (relative standard deviation (RSD) < 5.36 % ) were obtained for all compounds. This method was applied to quantify phenolic compounds in commercial rice wine samples (Chinese rice wine, Japanese sake, and Korean makgeolli), and good separation peaks were observed and catechin was the predominant phenolic in the samples. The average values of total phenolic contents of the three groups of rice wine were significantly different (p < 0.01). In conclusion, this procedure can be used to determine the phenolic compounds in various types of rice wines, as well as to characterize and differentiate rice wine samples.