Discriminant analysis of Mediterranean pine nuts (Pinus pinea L.) from Chilean plantations by near infrared spectroscopy (NIRS)

Pinus pinea L. is one of the most important nut species in the world given the high nutritional and culinary value of its seed, the pine nuts, with increasing demand. The objective of this study was to assess the potential of visible and near infrared spectroscopy (VIS + NIRS) to analyse different sample presentations and to discriminate geographical origins of Mediterranean pine nut grown in Chile. Pine nuts were collected from 76 adult trees in three growth macrozones previously defined for stone pine in Chile. Original spectroscopic data were obtained by means of a Foss NIRSystems 6500 SYII spectrophotometer using a transport module. Reflectance was employed in the wavelength range of 400–2500 nm. The best means of sampling for the pine nuts used in this study were also studied. After analysing the spectroscopic data, discriminant models were obtained by means of discriminant partial least square (DPLS) with all samples. For the three macrozones previously identified, 87.8% of samples was correctly classified in the cross validation stage with the best model for pine nuts spectra analysis, obtained with shelled intact pine nuts. Results indicate that NIRS technology is capable of differentiating between pine nut samples of different geographical origins with errors ranging between 12.2 and 9.2%, and demonstrate the potential of VIS + NIRS technology as a rapid and accurate method for predicting the geographical origin of Mediterranean pine nuts.     

HPLC determination of ochratoxin A in high consumption Tunisian foods

Samples (180) of high consumption food commodities from various regions of Tunisia were analysed to determine ochratoxin A contamination levels. A high performance liquid chromatography method for ochratoxin A determination was optimized. Samples were extracted with acetonitrile/water (80:20, v/v) solution and purified by immunoaffinity column. Average recoveries at 0.5 and 2 ng/g levels ranged from 84 ± 3.1 to 94 ± 1.2% with a between-day coefficient of variation (RSDR) of 3.8%. The method detection limit was 0.1 ng/g and ochratoxin identity was confirmed by methyl ester formation. The whole procedure was simple and fast if compared with other existing procedures. Performed analysis indicates that 45% of monitored samples were contaminated with levels ranging from 0.11 to 33.9 ng/g. The most contaminated commodities were barley, sorghum and wheat.     

基于光电磁及感官信号的食用植物油真实性快速鉴别方法研究进展

食用植物油营养丰富,是食品和饲料工业的重要基础原料,但掺伪现象普遍存在。因此食用植物油真实性鉴别方法不仅保护了消费者安全,同时也为维护食用油市场提供了有效的技术支撑。现有食用植物油真实性鉴别技术分为4类:基于理化法的方法、基于特征成分的方法、基于光电磁及感官信号的快速鉴别方法、基于代谢组学的方法。基于光电磁及感官信号的食用植物油真实性的快速鉴别方法非常适合于现场初筛,本文概述了这类方法的国内外研究进展,并对其研究发展趋势进行了展望。     

Solid-phase extraction and HPLC determination of Ochratoxin A in cereals products on Chilean market

Ochratoxin A (OTA) is a mycotoxin produced by different species of Aspergillus and Penicillium fungi. The presence of this mycotoxin in cereals-based products has relation with manufacturing practices, especially with storage conditions. An extraction procedure for OTA from wheat-based products was implemented in this study. The method uses an alkaline extraction with NaHCO₃, purification with Sep-Pak^® RP-18 cartridges; and quantitative analysis by high performance liquid chromatography with fluorescence detection. The presence of OTA was confirmed by the formation of Ochratoxin A methyl ester. The method shows good validation parameters with a rate of recovery rate over 95%, limits of detection and quantification of 0.6 and 2.1 μg kg^?1, respectively. Once the method was validated; 31 samples including, flour, corn starches and rice were analyzed. About 70% of flour samples, 50% of rice and 63% of corn starch samples resulted positives for OTA.