A low power voltage limiter for a full passive UHF RFID sensor on a 0.35 μm CMOS process

This paper presents a low power voltage limiter design for avoiding possible damages in the analog front-end of a RFID sensor due to voltage surges whenever readers and tags are close. The proposed voltage limiter design takes advantage of the implemented bandgap reference and voltage regulator blocks in order to provide low deviation of the limiting voltage due to temperature variation and process dispersion. The measured limiting voltage is 2.9 V with a voltage deviation of only ±0.065 V for the 12 measured dies. The measured current consumption is only 150 nA when the reader and the tag are far away, not limiting the sensitivity of the tag due to an undesired consumption in the voltage limiter. The circuit is implemented on a low cost 2P4M 0.35 μm CMOS technology.     

Dynamic evaluation of two configurations for a hybrid DFIG‐based wind turbine integrating battery energy storage system

Hybrid systems comprising battery energy storage systems (BESSs) and wind power generation entail considerable advances on the grid integration of renewable energy. Doubly fed induction generators (DFIGs) stand out among different wind turbine (WT) technologies. On the other hand, electrochemical batteries have proved to be valid for these purposes. In this paper, a comparative analysis is carried out between two alternative configurations for hybrid WT‐BESS systems, where the BESS is connected either outside or inside the DFIG. The modeling of these two configurations and the control systems applied for achieving the coordinate operation of the energy sources (DFIG and batteries) are illustrated. The hybrid systems under study are evaluated by simulation under normal operation (wind speed fluctuations and grid demand changes) and grid faults. Simulation results show that both configurations improve the grid integration capability of the WT, although the configuration with external BESS presents better results since it can provide additional active/reactive power injection. Copyright © 2014 John Wiley & Sons, Ltd.     

Determination of the precision of the fatty acid analysis of Iberian pig fat by gas chromatography. Results of a mini collaborative study

A collaborative study was carried out to determine the repeatability (error in each laboratory) and reproducibility (error between the different laboratories) of the fatty acid analysis of Iberian pig fat by gas chromatography. To do this, a comparison was made, in accordance with the ISO 5725-2 procedure, of the weight percentage (%) of the main fatty acids (C16:0, C18:0, C18:1 and C18:2) in 60 samples, determined by six laboratories. The results obtained for the relative standard deviation of the repeatability (0.56, 0.49, 0.29, and 0.69%) and for the relative standard deviation of the reproducibility (3.04, 3.54, 1.78 and 2.86%) show that the accuracy obtained is adequate for this analysis method, and in the same order or even higher than that obtained by other authors in similar samples. The differences between the results obtained on using two extraction methods of liquid fat from subcutaneous adipose tissue were recorded with no significant differences being observed between them.     

Subcutaneous and intermuscular fat characterisation of dry-cured Iberian hams

The fatty acid composition of the triacylglycerols and free fatty acids of subcutaneous (internal and superficial layers) and intermuscular fat and the contribution of these fatty acids to the formation of volatile compounds were determined in dry-cured Iberian ham. The profile of the fatty acids and volatile compounds showed that lipolytic and oxidative processes occur more intensively in subcutaneous than intermuscular fat, however, few differences were found compared to those found in ham lean.     

The effect of fructooligosaccharides on the sensory characteristics of cooked sausages

The effect of a short chain fructooligosaccharide on the sensory properties of conventional and reduced-fat cooked meat sausages has been studied in products in which a fat reduction of close to 40% was obtained. The fibre assayed was used in sufficient amounts to constitute between 2% and 12% of the final product. The energy value reduction of the final products was close to 35%. Instrumental measurements of colour and texture were performed. Sensory properties were estimated by a hedonic test. A correlation principal component analysis was performed. The results showed that the sensory and textural properties and the overall acceptability were very good, which indicated that this fibre can be considered a good fat replacer in meat products. Thus, with its addition, a reduced calorie product enriched with soluble dietetic fibre is obtained.     

Comparative effect of the addition of α-, β-, or γ-cyclodextrin on main sensory and physico-chemical parameters

Although α-, β-, and γ-cyclodextrins (CDs) have been widely used to improve the color of different fruit juices, a comparative study of the effect of these natural CDs on other properties that also influence pear juice quality, such as odor and aroma, have not been reported yet. In this study, the comparative effect of the addition of α-, β-, and γ-cyclodextrin, the only CDs authorized to be used in the food industry by U.S. Food and Drug Administration (FDA) and European Union, on the pear juice quality was evaluated for the first time. Several instrumental and sensory properties of this fruit juice, such as color, volatile composition, odor, and aroma have been evaluated in the absence and presence of α-, β-, and γ-CD. A study of the aroma profile of pear juice showed that esters, aldehydes, alcohols, and terpenes were the most important chemical families. However, the addition of α-, β-, and γ-CD had different effects on both the concentration of individual volatile compounds and their chemical grouping. Furthermore, a trained sensory panel was used to evaluate color, overall odor, overall aroma, and overall quality of pear juice in the presence or absence of CDs. PRACTICAL APPLICATION: After comparing the effects of the addition of α-, β-, and γ-CD on pear juice, our final recommendation is to add α-CD (the natural CD formed by 6 units of glucose) to pear juice because it will significantly increase the global quality of the juice by reducing its browning but without producing a significant reduction in the aroma quality.     

Occurrence of Escherichia coli O157, O111 and O26 in raw ewe's milk and performance of two enrichment broths and two plating media used for its assessment

The occurrence of Escherichia coli O157, O111 and O26 in 159 raw ewe's milk samples was examined. Sample-aliquots were incubated simultaneously in TSB added with yeast extract (YETSB) and mTSB with novobiocin (N-mTSB). Serogroup-specific immunomagnetic separation (IMS) was then used and IMS beads were plated in a cefixime tellurite (CT)-containing media (CT-SMAC, CT-SBMAC and CT-RMAC for E. coli O157, O111 and O26, respectively) and E. coli O157:H7 chromogenic ID agar. A sweep of confluent growth from each medium was examined for the presence of E. coli O157 and O111 using PCR, and for E. coli O26 using a latex agglutination test. Enumeration of E. coli O157 and O111 was performed in the samples tested positive for the correspondent serogroup using the most probable number (MPN) method combined with PCR. Percentage occurrences of E. coli O157, O111 and O26 were 18.2, 8.2 and 5.7, respectively. Mean E. coli O157 and O111 levels were 0.22 and < 0.04 MPN/mL, respectively. Enrichment in YETSB resulted in higher detection rates of E. coli O157 and O26 than in N-mTSB. When YETSB was used as enrichment broth and for these last two serogroups, the analysis of the confluent growth from the CT-media gave more positive results than that from E. coli O157:H7-ID medium.     

A charcoal- and blood-free enrichment broth for isolation and PCR detection of Campylobacter jejuni and Campylobacter coli in chicken

The microaerophilic nature of Campylobacter and its requirement of ～5% O(2) for growth have complicated its recovery from foods. The addition to the enrichment media of oxygen quenchers such as charcoal or blood could interfere with PCR for its detection. In this study, a two-step simple aerobic method for Campylobacter detection is proposed. A modification of the Tran blood-free enrichment broth (BFEB), in which charcoal was excluded from the medium (M-BFEB), was compared with the original formulation and other enrichment broths. Campylobacter jejuni and Campylobacter coli were screened by PCR directly from the enrichment media. Various levels of pure cultures of C. jejuni and C. coli combined with Escherichia coli were inoculated into Preston, Bolton, BFEB, and the modified BFEB (M-BFEB). In addition, Campylobacter was inoculated onto retail purchased chicken skin and recovery was quantified. Rates of recovery after 24 to 48 h of enrichment at 42 °C under aerobic incubation for BFEB and M-BFEB and microaerobic incubations for Preston and Bolton broths were determined. Overall, our results indicated that the most sensitive medium was Bolton's, followed by either BFEB or M-BFEB; the least sensitive was Preston's. M-BFEB was directly coupled to a PCR assay to detect Campylobacter, avoiding intermediate plating. Campylobacter was detected in the presence of up to 10(8) E. coli cells per ml. M-BFEB facilitated detection of both C. jejuni and C. coli artificially inoculated onto chicken skin samples. M-BFEB coupled to PCR is a rapid and attractive alternative for isolation and identification of C. coli and C. jejuni from poultry.     

Immobilization of β-Glucosidase and Its Application for Enhancement of Aroma Precursors in Muscat Wine

Enzyme immobilization is becoming more widely practised in biotechnology because of the advantages that this method brings. In this study, commercial β-glucosidase for aroma released in winemaking was immobilized on diverse supports (alginate–chitin, chitosan–chitin) by using different methods. It was found that the most appropriate matrix was chitosan by adsorption and reticulation. The optimal immobilization conditions were pH 3.5, immobilization time 120 min, and concentration of cross-linker glutaraldehyde 0.25 %. Stability of the immobilized enzymes was assessed, which revealed a number of advantages, such as a lower enzyme dose required for immobilization (367 times lower than the free enzyme dose recommended by the manufacturer), high stability over time, and reusability. In vitro studies of cellobiose and in vivo studies of wine and aroma precursors isolated from grape must yielded similar outcomes with respect to enzyme hydrolysis of free and immobilized proteins.     

Proteins in Olive Fruit and Oil

This paper is a comprehensive review grouping the information on the extraction, characterization, and quantitation of olive and olive oil proteins and providing a practical guide about these proteins. Most characterized olive proteins are located in the fruit, mainly in the seed, where different oleosins and storage proteins have been found. Unlike the seed, the olive pulp contains a lower protein content having been described a polypeptide of 4.6 kDa and a thaumain-like protein. Other important proteins studied in olive fruits have been enzymes which could play important roles in olives characteristics. Part of these proteins is transferred from the fruit to the oil during the manufacturing process of olive oil. In fact, the same polypeptide of 4.6 kDa found in the pulp has been described in the olive oil and, additionally, the presence of other proteins and enzymes have also been described. Protein profiles have recently been proposed as an interesting strategy for the varietal classification of olive fruits and oils. Nevertheless, there is still a lot of knowledge without being explored requiring new studies focused on the determination and characterization of these proteins.