Analysis of regioisomers of triacylglycerols of northern currant seed oil by tandem mass spectrometry

Currant oils have special health properties due to their moderate contents of α‐linolenic, γ‐linolenic and stearidonic acids. The distribution of fatty acids (FA) in the triacylglycerols (TAG) may affect the beneficial effects. Seed oils of wild northern red currant (NRC) (Ribes spicatum L.) from Northern Finland and of wild alpine currant (AC) (R. alpinum L.) from the South‐West coast of Finland were investigated. The purified TAG were analysed by tandem mass spectrometry by applying the ammonia negative ion chemical ionisation – collision‐induced dissociation method. Molecular weight fractions rich in C18:3 FA and C18:4 FA were investigated. Of the total oil, the molecular weight species 54:7 (ACN:DB), 54:8 and 54:9 were more abundant in NRC than in AC, being 21.0%, 15.8%, 7.4% and 16.2%, 11.2%, 4.8%, respectively (p <0.05). The species 52:6 was more abundant in AC (3.1%) than in NRC (2.6%) (p <0.05). The preferential order of FA to be in the sn‐2 position in both berries was typically C18:1 > C18:2 > C18:4 > C18:3. No difference was observed between relative locations of C16:0 FA and C18:3 FA in either of the oils. Within the TAG consisting of FA combinations C18:3/C18:3/C18:1 (54:7), C18:1 was more preferentially in the sn‐2 position (p <0.05) in AC (93.2%) than in NRC (74.6%), and in the case of C18:3, the preference was vice versa. Within the molecular weight species 54:9, FA combination C18:4/C18:3/C18:2, linoleic acid preferentially occupied the secondary position (p <0.005) in both berries, and the proportion of the TAG regioisomer pair sn‐C18:3‐C18:4‐C18:2 + sn‐C18:2‐C18:4‐C18:3 was more abundant (30.2%) in NRC than in AC (15.3%). Within the TAG species 52:6, proportions of all the existing combinations, C16:0/C18:3/C18:3, C16:0/C18:4/C18:2 and C16:1/C18:3/C18:2, varied between the two berry species (p <0.005).     

Volatile compounds of Baltic herring analysed by dynamic headspace sampling–gas chromatography–mass spectrometry

European Food Research and Technology - The effect of storage time at 6&;nbsp;°C on the volatile compounds of Baltic herring was studied using the dynamic headspace–gas...     

Influence of different pretreatments on the accessibility of transglutaminase and tyrosinase to wool fibre proteins

Wool fibres are subject to a variety of industrial chemical treatments prior to finishing processes. The influence of such treatments on subsequent enzymatic treatments is still poorly characterised, but its importance is paramount to achieve maximal efficiency of enzymatic action on the fibres. The effect of such treatments on wool fibre structure and their significance on the accessibility of the enzymes transglutaminase and tyrosinase to their target amino acids within wool proteins was investigated. These enzymes are of great interest due to their potential as protein cross‐linkers and their capability to covalently graft beneficial compounds onto proteins. The accessibility of target amino acids was assessed using specific peptides tagged with fluorescent probes, followed by epifluorescence or confocal microscopy. Differences in the action of the different chemical pretreatments were found, with a treatment with permonosulphuric acid resulting in the greatest level accessibility to both enzymes, followed by chlorination and plasma treatments. This was confirmed by the increase in tensile strength of treated wool observed in the enzyme‐treated yarns. This work illustrates that the accessibility of these enzymes to their target aminoacids in solid substrates such as wool is key for their action and to achieve the desired property modifications. The techniques used have the advantage of permitting the visual monitoring of the diffusion of the active enzymes through the wool fibre structure and to relate this to the extent of enzymatic reaction. Crucially, this will allow an informed choice of the best wool processing stage at which to introduce such enzyme treatments.     

Effects of preparation procedures,packaging and storage on nutrient retention in peeled potatoes

The effects of preparation procedures and packaging on vitamin C, dietary fibre, sugars, ash and moisture contents were studied in prepeeled packaged potatoes during two cultivation seasons. The potato cultivars Bintje, Van Gogh and Nicola were studied. Potatoes of the Nicola cultivar had the highest initial vitamin C and sugar contents. Retention of nutrient contents in packaged, prepeeled potatoes was very good after a 7-day storage period. Vitamin C contents were higher in packaged potatoes than in fresh tubers when ascorbic acid was used in the washing solution but the levels decreased during the 7-day storage period. When calcium chloride was added as well into the washing solution vitamin C contents remained high throughout the storage period. These results show that it is possible to preserve the nutritional contents of packaged potatoes over a 7-day storage period. Cooking decreased vitamin C contents by about 30% and keeping the potatoes hot for 1 h after cooking decreased vitamin C contents a further 10%. © 1998 SCI.     

Vocational education approach: New TEL settings—new prospects for teachers’ instructional activities?

This study focuses on vocational education teachers’ instructional activities in a new technology-enhanced learning (TEL) setting. A content analysis is applied to investigate teachers’ and students’ interactions in a 3D game context. The findings illustrate that when teachers’ and students’ interactions are mediated by a game, teachers seem to apply different discussion activities to empower vocational learning than they do in traditional classroom settings. Additionally, the present study shows that teachers spontaneously develop new ways of supporting vocational learning processes. In more detail, two main types of instructional activities were identified: a “knowledge-providing” approach and a “joint problem-solving” approach. Additionally, findings illustrate how teachers using different types of instructional approaches are followed up with different processes by students. The article is concluded with a general discussion of the emerging challenges regarding the technological and pedagogical development of vocational education and teachers’ instructional activities in new TEL settings based on a more long-term design-based research project (ongoing since 2004).     

Recursive FIR filter structures on FPGA

A new approach to piecewise-polynomial approximation and recursive implementation structures for linear-phase Finite Impulse Response (FIR) filters have been recently proposed. In this paper, we describe hardware prototype implementations of the new structures for all four types of linear-phase FIR filters using a Field Programmable Gate Array (FPGA) based platform. Narrowband lowpass filters and narrowband differentiators are used as design examples to demonstrate the functionality and efficiency of the implementations. The required wordlength and resource usage is analyzed.     

Tyrosinase‐catalysed grafting of food‐grade gallates to chitosan: surface properties of novel functional coatings

Plasma‐activated biaxially oriented polypropylene (BOPP) films and paper substrate have been coated with functional chitosan solutions. Plasma treatment increased the amount of surface peroxide groups and carboxyl groups on the BOPP films. As a result of plasma activation, the surface energy increased from 30 to 50 dynes/cm. The enzyme tyrosinase catalysed the grafting of octyl gallate and dodecyl gallate to amino groups of chitosan polysaccharide. Resulting coatings exhibited strong antimicrobial activity against Gram‐positive Staphylococcus aureus and Gram‐negative Listeria innocua. After 24 h of incubation, a total reduction in both bacteria cell numbers varied between >4.9 and 1.4 logarithmic units. Grafted dodecyl gallate and octyl gallate at pH 6 were found to have the lowest reduction values of <3 logarithmic units for S. aureus, while 1.4 logarithmic reduction value was obtained for grafted dodecyl gallate at pH 6 against L. innocua. Chitosan coatings were also effective barrier layers against oxygen transmission although the transmission rates clearly increased in high‐humidity conditions. In dry conditions, however, the transmission rate of 2 cm³/(m² · 24 h) was obtained with chitosan‐coated BOPP. Coatings did not have any effects on water vapour transmission. Both gallates were successfully grafted at pH 6. As increased flocculation and colour formation indicated, the tyrosinase‐catalysed grafting was more powerful with octyl gallate. Dodecyl gallate containing chitosan coatings was more hydrophobic as compared to octyl gallate. Total migration of substances into 95% ethanol was ≥5 mg/dm², thus materials may be exploitable in packaging purposes in direct contact with certain foodstuffs. Copyright © 2008 John Wiley & Sons, Ltd.