Comparison of electromyographic pattern of sensory experts and untrained subjects during chewing of Mahon cheese

Use of electromyography (EMG) to monitor mastication is a relatively new concept in assessing food physical and sensory properties. Although expert assessment of cheese characteristics is widely used, the effect of training in sensory analysis on mastication patterns, as assessed using EMG is not well known. Nine samples of the same Mahon cheese (60 days ripening) were given to 24 subjects (8 experts, 16 untrained) and EMG recorded for each chewing sequence. Three samples were tested in a single session by each subject, and three sessions carried out on different days. EMG was recorded from four masticatory muscles for each subject. From EMG records the following was extracted: number of chews, chewing time, mean and maximum voltage of EMG bursts (i.e. chews) across chewing sequence, chewing work and chewing rate. No gender bias was found for the EMG parameters considered, therefore, as regards gender, each group was considered to be homogeneous. Variability within-subjects across samples was greater for experts than untrained subjects. Significant differences in chewing time, chewing work and chewing rate were found between the expert and untrained groups. Data analysis of the three sessions showed an influence of cognitive constructs, mediating states, on the chewing process. The experts were found to be goal driven as to their mastication process. Experts showed no significant differences between sessions, untrained subjects were found to vary their EMG output in successive sessions for number of chews, chewing time, mean voltage, and chewing work.     

Determination of trimethylamine in milk using an MS based electronic Nose

A simple, rapid, reliable and highly automated analytical method has been developed to determine trimethylamine (TMA) in milk using an MS based electronic nose (SMart Nose). A set of Swedish milk samples with and without naturally occurring TMA was used to compare this new method with sensory analysis and dynamic headspace (DHS) gas chromatography with flame ionisation detection (GC-FID). The results show good agreement between these three analytical methods. A lower detection limit (0.5 mg kg^-1) and better repeatability were achieved with this new method compared to both sensory and DHS GC-FID analyses (1-2 mg kg^-1). The user-friendly multivariate analysis software provided with the SMart Nose system was used for TMA determination via a numerical PCA. Using Excel, peak intensity, correlated with TMA concentration via a second order equation, gave similar results. Thus, this is an up to date method of choice for the quantitative determination of TMA in milk. It is also able to give further qualitative information on the milk analysed using the PCA analysis supplied with this equipment.     

Hydrogen isotopic enrichment: an indicator of biodegradation at a petroleum hydrocarbon contaminated field site

Compound-specific carbon and hydrogen isotope analysis was used to investigate biodegradation of benzene and ethylbenzene in contaminated groundwater at Dow Benelux BV industrial site. delta13C values for dissolved benzene and ethylbenzene in downgradient samples were enriched by up to 2+/-0.5 per thousand, in 13C, compared to the delta13C value of the source area samples. delta2H values for dissolved benzene and ethylbenzene in downgradient samples exhibited larger isotopic enrichments of up to 27+/-5 per thousand for benzene and up to 50+/-5 per thousand for ethylbenzene relative to the source area. The observed carbon and hydrogen isotopic fractionation in downgradient samples provides evidence of biodegradation of both benzene and ethylbenzene within the study area at Dow Benelux BV. The estimated extents of biodegradation of benzene derived from carbon and hydrogen isotopic compositions for each sample are in agreement, supporting the conclusion that biodegradation is the primary control on the observed differences in carbon and hydrogen isotope values. Combined carbon and hydrogen isotope analyses provides the ability to compare biodegradation in the field based on two different parameters, and hence provides a stronger basis for assessment of biodegradation of petroleum hydrocarbon contaminants.     

Sensitive and specific detection of almond (Prunus dulcis) in commercial food products by real-time PCR

Almond has been widely used in all sorts of food products, mostly due to its pleasant flavor and health benefits. However almonds can become an important health problem since they are responsible for triggering adverse immune responses in allergic individuals, and since they are present in many processed foods they are considered as a potential hidden allergen. Consequently, it's important for food processors and regulatory agencies to be able to ensure accurate labeling of foods to protect the safety of the public and to avoid expensive recalls. We propose a simple and highly sensitive approach to detect almond in a wide range of processed foods. The method consists of a real-time PCR assay targeting the gene encoding for the ITS1 in almond, using a nuclease (TaqMan) probe labeled with FAM and BBQ. Sensitivity of real time PCR was determined by analysis of raw and heat treated almond-wheat flour mixtures with a range of detection of 0.1–100,000 mg/kg. The assay was successfully trialed on a total of 214 commercial foodstuffs allowing the detection of trace amounts of almond down to the level of 0.1 mg/kg, and is therefore proposed as a ready-to-use analytical tool to trace almond allergens in foods.     

Wheat bran-based biorefinery 2: Valorization of products

Wheat bran is multi-layered and consists of different cell types with different chemical compositions. The relatively high content of protein as well as the small amount of lignin is the key differentiator to other lignocellulose containing biomasses. Following the classical route of a biorefinery, bran may be disintegrated to a high extent and separated into fractions of high purity in order to build up new chemicals which serve as precursors for higher polymerized compounds. Secondly, bran contains substances that are per se valuables, but need to be further separated and purified.     

Wheat bran-based biorefinery 1: Composition of wheat bran and strategies of functionalization

Wheat, together with maize and rice, accounts to about 90% of the world's cereal production. During the milling process, wheat bran, besides other valuable compounds such as wheat germ and parts of the endosperm, remains as major by-product. Wheat bran is composed of various histological cell layers, called the pericarp, testa, hyaline and aleurone layer and its weight ratio to milled wheat is about 25%. Annually, over 650 million tons of wheat are produced in the world, of which more than 69% are used for food. The thereby accruing biomass of wheat bran can be estimated as 150 million tons, which are basically used in the feed industry. Even if numerous studies have investigated potential health benefits of consuming more whole grain foods, the addition of bran to existing food systems may confer difficulties in terms of processing, nutrition or sensory acceptance by consumers. This review will summarize state-of-the-art technological approaches such as mechanical, thermal or enzymatic treatment used to modify the functional properties of wheat bran and coincidently describe the impact on the food system.     

Composition of meat and offal from weaned and fattened rabbits and results of stereospecific analysis of triacylglycerols and phosphatidylcholines

BACKGROUND: Rabbit meat has excellent nutritive properties. The purpose of this study was to characterize rabbit meat and offal; in particular, the lipid fraction was studied in order to evaluate total and positional fatty acid (FA) compositions of triacylglycerol (TAG) and phosphatidylcholine (PC) fractions. Eight samples of weaned and eight of fattened rabbits were considered. RESULTS: Fattened rabbit meat contained slightly higher protein percentage content (P < 0.05) in comparison to weaned (20.1% versus 18.0%). Calcium content was higher in meat than in offal, unlike sodium, iron, zinc, manganese and copper. The cholesterol content in offal was much higher than in meat. FA profiles of total lipid showed a high percentage of unsaturated fatty acids and an n‐6/n‐3 ratio of 10.3 for fattened rabbit meat. Stereospecific analysis of TAG and PC was carried out on an eight‐sample pool of each meat and offal from weaned and fattened rabbits. In all samples the sn‐2‐position was prevalently esterified with oleic and linoleic acids in TAG, with polyunsaturated fatty acids in PC. CONCLUSION: Lipids from rabbit meat presented higher content of monounsaturated FA and lower n‐6/n‐3 ratio in comparison to offal, which was characterized by higher cholesterol and mineral levels. Copyright © 2011 Society of Chemical Industry