Biomedical subjects

Svein Halvor Knutsen

Publications and source records attributed to Svein Halvor Knutsen.

6 recordsLinked to original sources

PubMed2006

Treatment of cereal products with a tailored preparation of trichoderma enzymes increases the amount of soluble dietary fiber.

Nutritionists recommend increasing the intake of soluble dietary fiber (SDF), which is very low in most cereal-based products. Conversion of insoluble DF (IDF) into SDF can be achieved by chemical treatments, but this affects the sensorial properties of the products. In this study, the possibility of getting a substantial increase of SDF from cereal products using a tailored preparation of Trichoderma enzymes is reported. Enzymes were produced cultivating Trichoderma using durum wheat fiber (DWF) and barley spent grain (BSG) as unique carbon sources. Many Trichoderma strains were screened, and the hydrolysis conditions able to increase by enzymatic treatment the amount of SDF in DWF and BSG were determined. Results demonstrate in both products that it is possible to triple the amount of SDF without a marked decrease of total DF. The enzymatic treatment also causes the release of hydroxycinnamic acids, mainly ferulic acid, that are linked to the polysaccharides chains. This increases the free phenolic concentration, the water-soluble antioxidant activity, and, in turn, the phenol compounds bioavailability.

Coumaric Acids↗

PubMed2006

Flavanol and bound phenolic acid contents in different barley varieties.

Different barley varieties, consisting of hulled and hull-less types, of normal, waxy, and high amylose starch, as well as two-rowed and six-rowed types, were analyzed for their main proanthocyanidins and bound phenolic acids. Variations in proanthocyanidin and phenolic acid contents were studied in different barley types as well as inter-relationships between the phytochemicals and polysaccharides. The main flavanols found in the analyzed barley varieties were two dimeric as well as four trimeric forms in addition to catechin. The total amount of flavanols ranged from 325 to 527 microg/g of fresh weight of barley flour. No evident associations were found between variations in proanthocyanidin levels and different barley types. The total amount of phenolic acids ranged from 604 to 1346 microg/g of fresh weight of barley flour, with ferulic acid as the dominating acid. The amount of phenolic acids varied according to occurrence or lack of hull, with significantly higher levels in the hulled varieties.

Coumaric Acids↗

PubMed2006

Screening of acrylamide contents in potato crisps using process variable settings and near-infrared spectroscopy.

In order to study the formation of acrylamide in potato crisps during processing, an experimental design was set up. The design variables were drying time (6 levels), frying temperature (2 levels) and frying time (8 levels). The design contained 36 samples, which were analysed for acrylamide contents using LC high-resolution mass spectroscopy (LC-HRMS), and fat contents using the Soxhlet apparatus. Prior to analysis, all potato crisp samples were ground and analysed on an NIRSystems 6500 near-infrared (NIR) spectrometer. The acrylamide contents were modelled by: (i) design variables using multiple linear regression, (ii) NIR spectra using partial least squares regression (PLSR) and (iii) design variables and NIR spectra in combination using a novel technique combining least squares regression on the former, and PLSR on the latter. The results showed that the NIR spectra alone or in combination with the design variables gave better prediction models for acrylamide than the design variables alone. This implies that the spectra contain chemical information that is not purely a result of the processing variables that were investigated in this experiment. NIR spectroscopy is proposed as a possible tool for screening and identification of potato crisps with a high acrylamide content.

Acrylamide↗

PubMed2006

Pectin isolated from white cabbage--structure and complement-fixing activity.

This study was done to investigate whether white cabbage contained polysaccharides with immunostimulatory activity using the complement-fixing test as an indicator. The main polysaccharide isolated was of pectin nature. Methanolysis and (13)C-NMR showed that the polymers consisted of highly esterified alpha-galactopyranoside (alpha-GalpA), significant amounts of alpha-arabinose furanoside (alpha-Araf), beta-Galp and lesser amounts of rhamnose in the pyranose form (Rhap) and xylose in the pyranose form (Xylp). Linkage analyses showed that the alpha-GalpA residues were mainly 1,4-linked with small amounts of 1,3,4-linkages. The alpha-Araf residues were mainly terminally (t)- and 1,5-linked, whereas beta-Galp was t-, 1,3-, 1,6-, and 1,3,6-linked. Positive Yariv reaction indicated polymers with arabinogalactan type 2 like structures. alpha-Rhap was mainly present as 1,2- and 1,2,4-linked residues and Xylp was t- and 1,4-linked. The molecular weight varied greatly and was from 10 to 150 kDa. Cabbage polymers had biological activity and this complement-fixing activity was greatly affected by hydrolytic removal of Araf from pectic side chains.

Arabinose↗

PubMed2005

Addition of glycine reduces the content of acrylamide in cereal and potato products.

The effects of adding amino acids on the content of acrylamide in potato crisps, French fries, flat breads, and bread crusts were investigated. Addition of glycine or glutamine during blanching of crisps reduced the amount of acrylamide by approximately 30% compared to no addition. No effect was found in French fries. Addition of glycine during doughmaking significantly reduced acrylamide in both flat breads and bread crusts. In bread crusts the reduction of acrylamide ranged from 50 to >90% depending on the baking condition. In flat breads the reduction varied between 60 and >95%.

Acrylamide↗

PubMed2004

Effective ways of decreasing acrylamide content in potato crisps during processing.

The aim of this work was to examine the effect of blanching or soaking in different acid solutions on the acrylamide content in potato crisps. Furthermore, the effects of a shorter frying time and a lower frying temperature combined with a postdrying were investigated. Soaking or blanching of potato slices in acidic solutions decreased the pH of potato juice and increased the extraction of amino acids and sugars. Potato crisps obtained after such pretreatments were characterized by lower acrylamide content. The most effective extraction of free amino acids and sugars as well as the largest decrease of acrylamide content (90%) in crisps was obtained when potato slices were soaked in acetic acid solution for 60 min at 20 degrees C. Shorter frying time followed by postdrying resulted in low-moisture potato crisps. Furthermore, the postdrying treatment gave a decreases in acrylamide content of approximately 70% when potato slices were fried at 185 degrees C and approximately 80% when potato slices were fried at 160 degrees C. Effective ways of decreasing acrylamide content in crisps production have been found. Crisps with low acrylamide content and good sensory quality can be obtained either by blanching in acetic acid as pretreatment or by a short frying followed by postdrying.

Acetic Acid↗