Sensitive and specific detection of pine nut (Pinus spp.) by real-time PCR in complex food products
Pine nuts are a known source of food allergens and several cases of adverse immunological reaction after ingestion have been reported. To protect allergic consumers, methods to unequivocally detect the presence of pine nuts in complex matrices must be developed. A Taqman-based real time PCR method for the detection of Pinus spp. was set up. A homemade pesto spiked at known concentration of pine nut powder was used as model food. Moreover, DNA was purified from commercial foods declaring or not the presence of pine nuts. The method displayed a very high efficiency and specificity for the genus Pinus. The intrinsic LOD was 1pg of DNA, while the practical LOD evaluated on model foods was 0.1ppm of pine nuts powder, the lowest ever registered for the detection of food allergens via real-time PCR. Finally, the declared presence/absence of pine nut in commercial foods was confirmed.
Evaluation of the nutraceutical, antioxidant and cytoprotective properties of ripe pistachio (Pistacia vera L., variety Bronte) hulls
Every year tons of pistachio hulls are separated and eliminated, as waste products, from pistachio seeds. In this study the hulls of ripe pistachios were extracted with two organic solvents (ethanol and methanol) and characterized for phenolic composition, antioxidant power and cytoprotective activity. RP-HPLC-DAD-FLU separation enabled us to identify 20 derivatives, including and by far the most abundant gallic acid, 4-hydroxybenzoic acid, protocatechuic acid, naringin, eriodictyol-7-O-glucoside, isorhamnetin-7-O-glucoside, quercetin-3-O-rutinoside, isorhamnetin-3-O-glucoside and catechin. Methanol extraction gave the highest yields for all classes of compounds and presented a higher scavenging activity in all the antioxidant assays performed. The same was found for cytoprotective activity on lymphocytes, lipid peroxidation and protein degradation. These findings highlight the strong antioxidant and cytoprotective activity of the extract components, and illustrate how a waste product can be used as a source of nutraceuticals to employ in manufacturing industry.
Bioassay-guided isolation of proanthocyanidins with antioxidant activity from peanut (Arachis hypogaea) skin by combination of chromatography techniques
Purification and bioassay-guided fractionation were employed to isolate proanthocyanidins with antioxidant activity from peanut skin (Arachis hypogaea Runner 886). The crude extract was prepared with acetone (60% v/v) and purified using chromatographic methods, including a semipreparative HPLC technique. As a result, two proanthocyanidins were isolated and identified using NMR, epicatechin-(2 β→O→7, 4 β→8)-catechin (proanthocyanidin A1) and epicatechin-(β→2 O→7, 4 β→8)-epicatechin (proanthocyanidin A2). Despite the structural similarity, differences were observed in their antioxidant activity. Proanthocyanidin A1 proved to be more active, with EC50 value for DPPH radical scavenging of 18.25μg/mL and reduction of Fe(3+)-TPTZ complex of 7.59mmol/g, higher than that of synthetic antioxidant BHT. This compound evaluated by ABTS(+) was similar to that of natural quercetin. Therefore, peanut skin is an important source of bioactive compounds that may be used as a mild antioxidant for food preservation.