Qualitative and quantitative analysis of characteristic free and bound phenolics in three colored quinoas

Quinoa is a good source of phenolics,which both exist as free and bound forms.In order to mark clear the characteristic free and bound phenolics in different quinoa samples,in this study,characteristic free and bound phenolics in three colored quinoas including WQ(white quinoa),RQ(red quinoa)and BQ(black quinoa)were investigated.Result showed a total of 14 phenolics both acted as free and bound form were analyzed in three colored quinoas(WQ,RQ and BQ).Gallic acid,vanillic acid,epicatechin,p-coumaric acid and quercetin existed both as free and bound forms were common phenolics in quinoas.The highest total free phenolics(238.10 mg/kg)and bound phenolics(3377.75 mg/kg)were presented in WQ and RQ,respectively.It indicated WQ and RQ were respectively good source of free and bound phenolics.Moreover,characteristic free and bound phenolics in three colored quinoas could be well analyzed by principal component analysis(PCA),indicating it was an effective and reliable method in distinguishing three colored quinoas based on their characteristic free and bound phenolics,respectively.

The Antioxidant Activity of Barley Malt Rootlet Extracts in Heated Corn Oil at Frying Temperature

In this study the antioxidant activity of barley malt rootlet (BMR) extracts was evaluated in heat treated corn oil up to 5 hours at 185°C frying temperature. The antioxidant activity of BMR extracts was measured at 25, 50, 100 and 150 ppm concentrations. The free and bound antioxidant phenolics were extracted from BMR using three different extraction methods. Conventional solvent extraction (CSE), microwave assisted extraction (MAE) and autoclave assisted pretreated solvent extraction (APSE). In the present experiment, the total phenolic content and antioxidant activity of the various extracts were measured. Thiobarbituric acid reactive substances (TBARS) assay was used to evaluate the ability of the BMR to protect lipid peroxidation in corn oil at 185°C frying temperature. The formation of TBARS at 5 hours of heat treated corn oil has shown similar antioxidant levels in 150 ppm butylated hydroxytoluene (BHT) or MAE free phenolic extract added to corn oil. TBARS value for BHT was 1.896 ± 0.013 μg/mL of corn oil and for MAE was 1.896 ± 0.034 μg/mL of corn oil. The highest level of antioxidant activity was found for the free phenolic extracts. The order of inhibition of oxidation was found to be for free phenolics as follows: BHT (100 ppm) > APSE (50 ppm) > MAE (100 ppm) > CSE (100 ppm).

Characterizing traditional rice varieties grown in temperate regions of Italy:free and bound phenolic and lipid compounds and in vitro antioxidant properties

Objectives:A comparative study regarding the fatty acid profiles and antioxidant properties of the two most common varieties of rice(Carnaroli and Karnak)cultivated in Sybaris(Southern Italy)was conducted.Carnaroli variety from Pavia district(Northern Italy)was also investigated.Methods:Free and bound lipids were separately extracted.Fatty acid composition was determined by high resolution gas chromatography(HRGC).Free and bound phenolic acids were determined using high performance liquid chromatography(HPLC).The antioxidant properties were assessed using 2,2’-diphenyl-1-picrylhydrazyl(DPPH)radical scavenging assay.Results:The total lipid content was found to be higher in both Sybaris species with respect to the Pavia variety.The lipid distribution was also significantly different.In particular,the amount of bound lipids(14.2-16.3 mg g−1)was higher than the free lipids(7.2-7.5 mg g−1),and unsaturated fatty acids(USFA)were significantly higher in the free-FA fraction than in bound-FA in both Sybaris varieties.By contrast,Carnaroli variety from Northern Italy displayed a higher content of free(5.3 mg g−1)than bound lipids(2.5 mg g−1)and a higher content of USFA in the bound-FA.The antioxidant activity of Pavia rice extract was higher than that of both Sybaris varieties.Conclusions:The two Sybaris varieties are richer in lipids than the Pavia rice,while exhibiting the same qualitative fatty acid profile with some differences in the content of individual fatty acids.The distribution of lipids(free or bound)was found to be significantly different in the Carnaroli varieties,highlighting the effects of different climatic and pedological areas.