Detection of the adulteration of olive oils by solid phase microextraction and multidimensional gas chromatography

The presence or absence of filbertone in 21 admixtures of olive oil with virgin and refined hazelnut oils obtained using various processing techniques from different varieties and geographical origins was evaluated by solid phase microextraction and multidimensional gas chromatography (SPME–MDGC). The obtained results showed that the sensitivity achievable with the proposed procedure was enough to detect filbertone and, hence, to establish the adulteration of olive oil of different varieties with virgin hazelnut oils in percentages of up to 7%. The very low concentrations in which filbertone occurs in some refined hazelnut oils made difficult its detection in specific admixtures. In any case, the minimum adulteration level to be detected depends on the oil varieties present in the adulterated samples. In the present study, the presence of R- and S-enantiomers of filbertone could be occasionally detected in olive oils adulterated with 10–20% of refined hazelnut oil.     

Differentiation of saffron from four countries by mid-infrared spectroscopy and multivariate analysis

Mid-infrared spectroscopy combined with multivariate analysis has been applied for the discrimination of 250 saffron samples from Greece (40 samples), Iran (87 samples), Italy (60 samples) and Spain (63 samples). The infrared spectra of saffron filament samples and their organic extracts were recorded. Principal component analysis was applied to different spectral regions. Then the principal components were used as variables in discriminant analysis. The best discriminatory approach was achieved in the spectral region 2000–700 cm⁻¹. The spectral region responsible for the differentiation of Italian samples is in the region of carbonyl group around 1746 cm⁻¹. The spectral region at around 1600 cm⁻¹ and the band at 1670 cm⁻¹ are responsible for the differentiation of samples from the remaining countries. From the original grouped cases, 93.6% were correctly classified. The correct classification rates for saffron samples from Greece, Iran, Italy and Spain were 90.0, 89.5, 96.7 and 98.4%, respectively. The combination of infrared spectroscopic technique with multivariate analysis is a rapid and ambient method to discriminate saffron samples in terms of geographical origin.     

Alternative woods for aging distillates-an insight into their phenolic profiles and antioxidant activities

Work has commenced on the study and characterization of wood native species (oak, chestnut, cherry, alder, ash, and beech), employed to a minor extent in enology, for their application in the elaboration of distillates. To this end, furanic and low molecular weight phenol compounds, total phenolic content, and antioxidant activity in alcoholic extracts by maceration of wood chips at 2 toasting levels were studied. Significant differences between samples, technologically relevant, were due both to species and toasting time. Furthermore, extracts showed interesting antioxidant activities equivalent in some cases to than those reported for alcoholic beverages aged in wood.     

辐照对蜂蜜中残留氯霉素和理化指标的影响

以蜂蜜为实验对象,60Coγ射线辐照9.3kGy剂量,比较辐照前后蜂蜜中残留氯霉素和理化指标的变化.结果表明:蜂蜜中氯霉素浓度从93.07μg/kg降低至0.82μg/kg,降解率达99.12%;羟甲基糠醛含量从23.93mg/kg降低至4.86mg/kg,降低了80%;辐照对蜂蜜水分、灰分、酸度、淀粉酶活性、还原糖和蔗糖含量等理化指标无明显影响.本研究证明辐照技术降低蜂蜜中残留的氯霉素是可行的,为解决当前蜂产品的质量安全问题提供有力的技术支撑.     

Retaining maximum antioxidative potency of wheat germ oil refined by molecular distillation

A process of physical refining wheat germ oil using the technique of molecular distillation (MD) is presented in this work. Wheat germ oil was obtained from the germ by solvent extraction using hexane and also by cold pressing. The oil extracted with hexane was degummed and bleached before deacidification in order to modify the parameters of phosphorus and color. The goal in carrying out the stage of physical refining by MD was to preserve the maximum amount of original antioxidative potential obtained from extraction of the crude oil. The effect of evaporation temperature of one‐stage MD on the efficiency of free fatty acid elimination was studied. The antioxidant portion was followed by means of analytic determination of tocopherols by high‐performance liquid chromatography. Tocopherol retention up to 98% was achieved in the oil extracted by pressing, and yields of up to 96% were achieved in the oil extracted with hexane. Copyright © 2007 Society of Chemical Industry     

GC检测虾中氯霉素残留的研究

建立了虾中氯霉素残留的带电子捕获检测器的气相色谱方法.通过改进虾样品前处理的操作,结果表明:氯霉素浓度在0.5μg/L～500μg/L的范围内呈良好的线性关系(R2=0.9996),最低检测限为0.1μg/kg,定量限为0.5 μg/kg;向样品中分别添加10、100、200μg/kg3个浓度水平的氯霉素回收率分别为99.3%、109.9%和116.9%,变异系数为3.1%～9.2%.该方法灵敏.精密度高.     

SYNERGISTIC EFFECT OF VITAMIN B1 ON SANITIZER AND DISINFECTANT TREATMENTS FOR REDUCTION OF BACILLUS CEREUS IN RICE

The synergistic bactericidal effects of vitamin B₁ (thiamine dilauryl sulfate) and the efficacy of commercial sanitizers for minimization of Bacillus cereus contamination in cooked rice were investigated. Sanitizer-treated rice exhibited a greater reduction than water-treated rice, while sanitizer-treated rice with Vitamin B₁ produced an even greater reduction. The treatments for B. cereus in rice included (1) 100 ppm hydrogen peroxide with 500 ppm vitamin B₁; (2) 200 ppm hydrogen peroxide with 100 ppm vitamin B₁; (3) 400 ppm hydrogen peroxide; (4) 50 ppm chlorine with 500 ppm vitamin B₁; (5) 60 ppm chlorine with 300 ppm vitamin B₁; (6) 70 ppm chlorine with 100 ppm vitamin B₁; (7) 80 ppm chlorine; and (8) 100,000 ppm ethanol with 500 vitamin B_1. All treatments completely eliminated B. cereus in rice. The sensory properties of all sanitizer-treated cooked rice did not differ significantly from the same properties for water-treated cooked rice.

PRACTICAL APPLICATIONS

The prevalence of Bacillus cereus in rice and rice products has been documented and control of the growth of B. cereus in rice is an important consideration. The results obtained from this study can be of use to rice producers in the manufacture of safe products. Although chemical disinfectants can be used to reduce the amount of B. cereus in rice, vitamin B₁ can also be used as an effective additive that reduces the amount of disinfectant use via a synergistic antimicrobial effect. The increasing use of chemical disinfectants for safety in the food industry can be reversed using our method.     

Influence of different aging systems and oak woods on aged wine color and anthocyanin composition

The evolution of a red wine, Cigales appellation in origin, was studied during its storage in three different aging systems (barrels, chips, and staves) made of different kinds of oak wood (American, French, and Hungarian). The results obtained were analyzed in order to determine the content of anthocyanins in wine according to the aging system used. The studied variables were monoglucosides of delphidin, cyanindin, peonidin, petunidin and malvidin (as acetic and p-coumaric esters), as well as vitisin A, malvidin-3-O-caffeylglucoside, and color variables. The relationship between the anthocyanins and color variables stressed the importance of these compounds during the formation of pigments characteristic of aged wine, and highlighted how they are affected by the aging system chosen.Analysis of the results allowed us to define the evolution of the wine accordingly to the aging system and the botanical species of wood used. Wine treated with chips evolved more quickly than wines treated with the other two systems, because there was a higher loss of anthocyanins and an increase in brownish tonalities. On the other hand, wine treated with Hungarian oak wood suffered a slightly higher loss of anthocyanins than those aged with French and American oak wood.     

Activated carbons as potentially useful non-nutritive additives to prevent the effect of fumonisin B1 on sodium bentonite activity against chronic aflatoxicosis

Aflatoxin B₁ (AFB₁) and fumonisin B₁ (FB₁) are mycotoxins that often co-occur in feedstuffs. The ingestion of AFB₁ causes aflatoxicosis in humans and animals. Sodium bentonite (NaB), a cheap non-nutritive unselective sequestering agent incorporated in animal diets, can effectively prevent aflatoxicosis. Fumonisins are responsible for equine leukoencephalomalacia and porcine pulmonary oedema, and often have subclinical toxic effects in poultries. Fumonisin B₁ and aflatoxin B₁ are both strongly adsorbed in vitro on sodium bentonite. Co-adsorption studies, carried out with a weight ratio of FB₁ to AFB₁ that mimics the natural occurrence (200:1), showed that FB₁ greatly decreases the in vitro ability of NaB to adsorb AFB₁. The ability of two activated carbons to adsorb FB₁ was also investigated. Both carbons showed high affinity for FB₁. A complex behaviour of the FB₁ adsorption isotherms with pH was observed. In vitro results suggest that under natural contamination levels of AFB₁ and FB₁, a mixture of activated carbon and sodium bentonite might be potentially useful for prevention of sub-acute aflatoxicosis.