Antioxidant and anti-inflammatory activities of freeze-dried grapefruit phenolics as affected by gum arabic and bamboo fibre addition and microwave pretreatment.

BACKGROUND: Recent epidemiological studies have suggested that phenolic compounds present in grapefruit play an important role in the bioactive properties of this fruit. However, the consumption of fresh grapefruit is low. Freeze-dried powdered grapefruit can be an alternative to promote this fruit consumption. To improve the quality and stability of the powdered fruit, encapsulating and anticaking agents can be added. In the present study, different grapefruit powders obtained by freeze-drying with the addition of gum arabic (1.27 g per 100 g) and bamboo fibre (0.76 g per 100 g) with and without a pre-drying microwave treatment were compared with the fresh and freeze-dried fruit with no carriers added, aiming to evaluate the effect of these preservation processes on phenolics content and on its antioxidant [1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and ferric reducing ability of plasma (FRAP)] and anti-inflamatory (evaluated in RAW 264.7 macrophages) capacities. RESULTS: Freeze-drying and gum arabic and bamboo fibre addition significantly increased total phenolics, as well as the antioxidant and anti-inflammatory activities (by inhibiting nitric oxide production of lipopolysaccharide activated RAW 264.7 macrophages), of grapefruit. An additional increase in these parameters was obtained with microwave pretreatment before freeze-drying. CONCLUSIONS: The combined addition of gum arabic and bamboo fibre to grapefruit puree and the application of a microwave pretreatment improve the functional properties of the fruit without showing cytotoxicity in vitro. © 2017 Society of Chemical Industry.

Effects of microwave-assisted hot water treatments designed against Mexican fruit fly (Anastrepha ludens) on grapefruit (Citrus paradisi) quality.

BACKGROUND: Hot water treatment (HWT) against Anastrepha ludens was developed achieving 48 °C in the core of grapefruits and holding it for 6 min. After heating, the grapefruits were hydro-cooled and stored at 23 °C and analyzed for 16 days. The effect of microwave-assisted HWT (MW-HWT) on grapefruit quality was analyzed and compared with the quality of fruits treated with HWT and control fruits (without treatment). The physicochemical properties and chemical composition of essential oil were analyzed. RESULTS: MW-HWT was equivalent to HWT according to accumulated heat calculations, with the advantage of being shorter. Treatments significantly affected the weight, color, maturity index, juice content, firmness, titratable acidity, pH, and ascorbic acid content of the grapefruits (P < 0.05), but had no effect on the total soluble solids (P > 0.05). The major components identified in the essential oil were d-limonene and ß-myrcene, compounds responsible of the scent of the grapefruits. CONCLUSION: MW-HWT was shorter (130 min) and had a lesser effect on the quality of the grapefruit when compared with fruits under HWT (188 min duration). Thus, this treatment could be considered as an alternative method against the Mexican fruit fly in grapefruit. © 2017 Society of Chemical Industry.

UV-irradiated grapefruit juice loses pharmacokinetic interaction with nifedipine in rats.

In the present study, UV-irradiated grapefruit juice was used to investigate the effects of UV light on nifedipine pharmacokinetics. Grapefruit juice in quartz vessels was UV irradiated (302 nm) with a transilluminator for 0 to 6 h at 4 degrees C, and furanocoumarins, potent contributors to the pharmacokinetic interaction, in each juice sample were measured using HPLC. The concentrations of all three types of furanocoumarins, bergamottin, 6',7'-dihydroxybergamottin, and bergaptol, decreased in a time-dependent manner. Concentrations of bergamottin, 6',7'-dihydroxybergamottin, and bergaptol were decreased to 1.66, 1.98, and 5.58%, respectively, after UV irradiation for 6 h. Two milliliters of untreated and UV-irradiated grapefruit juice were preadministered into the duodenum in rats to assess the effects of UV irradiation on nifedipine pharmacokinetics in vivo. After 30 min, nifedipine was intraduodenally administered at a dose of 3 mg/kg body weight. The nifedipine concentrations in the plasma samples were determined using HPLC. A significant increase in the area under the concentration-time curve of nifedipine was observed in untreated grapefruit juice to 1.6-fold that in the control group, but not in the UV-irradiated grapefruit juice. These findings suggest that UV irradiation is useful to eliminate pharmacokinetic interactions with grapefruit juice.