Antioxidant activity of Citrus paradisi seeds glyceric extract

The antioxidant activity of Citrus paradisi (grapefruit) seeds glyceric extract dissolved in ethanol and in aqueous media was evaluated using three different methods: evaluation by DPPH assay, by 5-lipoxygenase assay and by luminol/xanthine/xanthine oxidase chemiluminescence assay. The total phenolic content was determined by the Prussian Blue method opportunely modified. The grapefruit seeds glyceric extract utilized as aqueous solutions demonstrated antioxidant properties better than those displayed by alcoholic solutions.     

On-line HPLC-DPPH screening method for evaluation of radical scavenging phenols extracted from apples (Malus domestica L.)

An on-line HPLC-DPPH screening method for phenolic antioxidants in apple methanol/water (80:20, v/v) extracts was applied. The determination of antioxidants was based on a decrease in absorbance at 515 nm after postcolumn reaction of HPLC-separated antioxidants with the 2,2'-diphenyl-1-picrylhydrazyl radicals (DPPH*). Each of the antioxidants separated by the HPLC column was observed as a negative peak corresponding to its antioxidative activity. The on-line method was applied for quantitative analysis of the antioxidants. A linear dependence of negative peak area on concentration of the reference antioxidants was observed. For validation of the on-line method the limit of detection, LOD (microg/mL), and the limit of quantification, LOQ (microg/mL), of the phenolic compounds were determined. Comparison of the UV and DPPH radical quenching chromatograms with authentic compounds identified catechin, chlorogenic acid, caffeic acid, epicatechin, and phloridzin in the apple cultivars (Lobo, Golden Delicious, and Boskoop), and the distribution of total antioxidant activity was calculated.     

Herbage intake and milk yield in Comisana ewes as effect of 4 vs 7 h of grazing during late lactation

Thirty-two Comisana ewes at late lactation were used in two trials carried out during late spring in 2 consecutive years, with the aim to evaluate the effect of the duration of grazing on herbage intake and performance. In each trial, 16 pluriparous Comisana lactating ewes were equally divided into two groups which grazed in two separate areas of natural pasture from 11:00 to 15:00 h (group 4H) or from 10:00 to 17:00 (group 7H). A concentrate mixture (500 g/day) was also offered to each ewe. The mean maximum temperature was, respectively, 23.5 ± 3.8 °C during experiment 1 and 27.0 ± 3.1 °C during experiment 2. Probably as a consequence of the differences in climatic conditions, the results on herbage intake and milk production were different during the two trials. Herbage dry matter intake was not affected by the duration of grazing during trial 1, whereas it was significantly lower in 4H group compared to that in 7H group (0.67 vs 1.02 kg/day; P < 0.001) during trial 2. It could be hypothesised that while with lower environmental temperature (trial 1), the 4H ewes were able to reach good intake levels despite grazing during the hottest hours; with higher temperatures throughout the trial (trial 2), the 4H ewes reduced ingestion. Milk production was higher in 4H group during trial 1 (778 vs 707 g/day; P = 0.006), whereas it was not affected by the number of hours of grazing during trial 2, despite the higher intake levels reached by the 7H group. In conclusion, 3 extra hours of grazing for ewes at late lactation on a low quality pasture could be nullified in terms of yield response.