Feral Temelli

Chemical composition and oxidative stability of flax, safflower and poppy seed and seed oils.

Three seeds of Turkish origin, flax, poppy and safflower were analyzed for their proximate, fatty acids, tocols (tocopherols and tocotrienols) and total phenolic composition, and oxidative stability of their oil. The major fatty acid in the flax oil was alpha-linolenic acid, comprising 58.3% of total fatty acids, whereas poppy and safflower oils were rich in linoleic acid at 74.5% and 70.5% level, respectively. The amount of total tocols was 14.6 mg/100g flax, 11.0mg/100g poppy and 12.1mg/100g safflower seed. Flax and poppy oil were rich in gamma-tocopherol as 79.4 mg/100g oil and 30.9 mg/100g oil, respectively, while alpha-tocopherol (44.1g/100g oil) was dominant in safflower oil. Only alpha- and gamma-tocotrienol were found in the oils. Oxidative stability of oils was measured at 110 degrees C at the rate of 20 L/h air flow rate, and poppy oil (5.56 h) was most stabile oil followed by safflower oil (2.87 h) and flax oil (1.57). There were no correlation between oxidative stability and unsaturation degree of fatty acids and tocol levels of the oils. All of the seeds investigated provide a healthy oil profile and may have potential as a source of specialty oils on a commercial scale.

Supplementation of the Diet with High-Viscosity Beta-Glucan Results in Enrichment for Lactobacilli in the Rat Cecum

ABSTRACT BBn (BioBreeding) rats were fed casein-based diets supplemented with barley flour, oatmeal flour, cellulose, or barley β-glucans of high [HV] or low viscosity [LV] in order to measure the prebiotic effects of these different sources of dietary fiber. The dietary impact on the composition of the cecal microbiota was determined by the generation of denaturing gradient gel electrophoresis (DGGE) profiles of PCR-amplified 16S rRNA gene sequences. The DGGE profiles produced from the cecal microbiota of rats within each dietary group were similar, but consensus profiles generated from pooled bacterial DNAs showed differences between rat groups. Animals fed HV glucans (HV-fed rats) had DGGE consensus profiles that were 30% dissimilar from those of the other rat groups. A 16S rRNA gene fragment that was more conspicuous in the profiles of HV-fed animals than in those of cellulose-fed rats had sequence identity with Lactobacillus acidophilus. Measurements of L. acidophilus rRNA abundance (DNA-RNA hybridization), the preparation of cloned 16S rRNA gene libraries, and the enumeration of Lactobacillus cells (fluorescent in situ hybridization) showed that lactobacilli formed a greater proportion of the cecal microbiota in HV-fed rats. In vitro experiments confirmed that some lactobacilli utilize oligosaccharides (degree of polymerization, 3 or 4) present in β-glucan hydrolysates. The results of this study have relevance to the use of purified β-glucan products as dietary supplements for human consumption.

β-Glucan from Two Sources of Oat Concentrates Affect Postprandial Glycemia in Relation to the Level of Viscosity

Objective: Soluble dietary fiber has been shown to attenuate the postprandial rise in blood glucose levels and reduce the risk of type 2 diabetes and cardiovascular disease. This effect seems to be related to its rheological properties including viscosity. We examined the intra-fiber variability between two different processing methods of concentrating β-glucan from oats (aqueous vs. enzymatic) in relation to the level of viscosity of β-glucan and its effect on postprandial glycemia in healthy individuals. Design: In an acute, randomized, double-blind, crossover study, 11 healthy subjects (gender: 5M:6F; age: 34 ± 5 years; BMI: 23 ± 0.8 kg/m2) were randomly assigned, on three separate occasions, to consume one of three fiber-matched treatments along with a 75g oral glucose drink. The enzymatically processed β-glucan (Oat-A) differed from β-glucan processed through the aqueous method (Oat-B) solely with regard to viscosity. Finger-prick capillary blood samples were obtained at fasting and at 15, 30, 45, 60, 90 and 120 min after the start of the test drink. The viscosities of the fiber drinks were determined (Paar Physica UDS200 viscometer). Results: Rheological measurements demonstrated that Oat-A had a significantly higher viscosity than Oat-B and control at 5, 15, 30, 60, and 120 min (p < 0.001). The incremental area under the glucose curve (AUC) on Oat-A was 19.6% and 17% lower than that of Oat-B and control, respectively (p < 0.01). Conclusions: This study shows that processing oat β-glucan through enzymatic, rather than by aqueous methods, preserves the viscosity and improves postprandial glycemic control.

Effect of Extraction Conditions on Yield, Composition, and Viscosity Stability of Barley β-Glucan Gum

ABSTRACT Cereal β-glucan can function as a thickener, but endogenous β-glucanase enzymes of the grain cleave β-glucan, reducing its viscosity. Although different extraction techniques have been developed, the viscosity stability of β-glucan gum has not been reported. The objective of this study was to investigate the effect of extraction treatments on the yield, purity, and viscosity stability of barley β-glucan (BBG) gum. A regular barley cultivar, Condor, and a waxy cultivar blend were extracted at pH 7–10 and 55°C for 0.5 hr. Four extraction conditions were evaluated: 1) extraction at high pH with no additional heat treatment; 2) boiling of extract; 3) prior refluxing of flour with 70% ethanol; and 4) treatment of extract with thermostable α-amylase for purification. Viscosity of extracts was monitored for ≥24 hr at 25°C. The highest β-glucan purities were achieved with a boiled Condor extract at pH 7 (81.3% db, 4.1% yield) and with refluxed waxy barley extracted at pH 8 and treated with α-amylase and ...

Extraction of phospholipids from canola with supercritical carbon dioxide and ethanol

The potential use of supercritical (SC)-CO2/ethanol mixture for the extraction and fractionation of phospholipids (PL) from flaked canola seeds, canola meal, and acetone insolubles (AI) was investigated. PL extraction was possible when ethanol was used as a cosolvent in SC-CO2. PL recovery of 20.8% was achieved when canola flakes were extracted at 70°C and 55.2 MPa with SC-CO2/10%EtOH after iol removal with neat SC-CO2. Soaking of canola meal with ethanol prior to SC-CO2/EtOH extraction increased PL recovery to 30.4%. PL content of the extracts increased with decreasing triglyceride concentration in the feed material and increasing amounts of ethanol added to SC-CO2 or used for soaking. Fractionation of Al gums resulted in extracts containing 50% PL, of which 90% was phosphatidylcholine (PC); but yields were low, even after soaking treatment, due to caking. SC-CO2/EtOH mixture may be used to extract PC-enriched PL from flaked canola seeds, canola meal, and AI. However, further research is needed to improve extraction efficiency.

Stabilization of emulsions and foams using barley β-glucan

Abstract Barley β-glucan (BBG) is receiving increasing attention as a food hydrocolloid. Stability of foams and emulsions was assessed using whey protein concentrate (WPC) as an emulsifier and foaming agent, and BBG gum extracted at pilot plant or laboratory scale as a stabilizer. WPC had a significant lowering effect (P⩽0.05) on surface tension of water and water–oil interfacial tension, while the effect of β-glucan was time dependent. Differential scanning calorimetry (DSC) showed that BBG formed a gelled network, responsible for stabilizing, that melts at 58–62°C. Reversible gels of BBG melt around 63°C. Emulsion (50% o/w) droplet size decreased several fold when prepared with BBG gum and phase separation was substantially decreased. Foam volume and 50% drainage were significantly (P⩽0.05) improved upon addition of β-glucan. Sugar significantly enhanced foam stability only when used together with β-glucan. BBG shows potential as a stabilizer in foam- and emulsion-type food products.

Volatile flavour composition of cooked by-product blends of chicken, beef and pork : a quantitative GC-MS investigation

Abstract Volatile flavour composition of cooked chicken (CB), beef (BB) and pork (PB) by-product blends was investigated using gas chromatography–mass spectrometry (GC–MS) and the results were compared with those for cooked chicken white muscles (CM), beef shoulder muscles (BM) and pork shoulder muscles (PM), respectively. The total volatile flavour concentration of CB (4828 μg/kg sample) was three times higher than that observed for CM (1604 μg/kg sample). In BB and PB, the total volatile concentration was lower than that observed for their muscle counterparts. Aldehydes, alcohols and nitrogen- and/or sulphur-containing compounds dominated the volatile flavour profiles of CM, BM and PM while a marked dominance of alcohols was evident for CB and BB. The concentration of aldehydes in BB and PB was lower by about 66 and 70%, respectively, than that evident for the corresponding cooked muscles. The difference between the concentration of aldehydes in CM and CB was ∼7%. These differences between the volatile flavour profiles of cooked muscle samples and the corresponding by-product blends may be attributed to the compositional differences in aroma precursors in the samples. This study demonstrated that the volatile flavour compounds in cooked meat by-products are recoverable, but a careful blending of different by-products of a particular species in appropriate proportions may be necessary to generate an aroma similar to that of the respective cooked muscles.

Interactions between meat proteins and barley (Hordeum spp.) β-glucan within a reduced-fat breakfast sausage system.

Barley β-glucan, a soluble fibre component with health benefits, has the potential to be used as a fat replacer in meat systems. Interactions between meat proteins and β-glucan gum were examined in reduced-fat (12%, w/w) sausages formulated with β-glucan at 0.3% (w/w) (0.3β-gl) and 0.8% (w/w) (0.8β-gl) levels, as well as high- and reduced-fat controls. Cooking loss results indicated that β-glucan gum held more water in cooked sausages than control gum (carboxymethyl cellulose), due to its ability to form a tighter network within the protein matrix, as shown by scanning electron microscopy. In a raw system, β-glucan gum was not as effective at retaining moisture as a stable protein network, formed by heating. Differential scanning calorimetry results showed that sausages with a higher gum to protein ratio required additional energy for protein denaturation to occur. Findings indicate that β-glucan gum increases the amount of moisture held in a cooked meat protein system, due to the physical entrapment of water, when compared to the high-fat control, but is similar to the reduced-fat formulation with added water.

Extraction and purification of ω-3 fatty acids with an emphasis on supercritical fluid extraction—A review

Abstract ω-3 fatty acids have been known to have potential health benefits. These fatty acids are currently in demand in pure form by clinicians to further the understanding of their mechanism of action in the human system. The chemistry sources of ω-3 fatty acids and processing methods for extraction and purification will be summarized in this review. Emphasis is given on recent advances in technological developments, particularly, supercritical fluid extraction and chromatography. With a brief introduction of the principles and advantages of using supercritical fluids for extraction and chromatography, methods involving direct extraction of oil rich in ω-3 fatty acids and those used for concentration of these fatty acids in the ester form are discussed.

β-Glucan extracts inhibit the in vitro intestinal uptake of long-chain fatty acids and cholesterol and down-regulate genes involved in lipogenesis and lipid transport in rats

BACKGROUND Dietary fiber reduces the intestinal absorption of nutrients and the blood concentrations of cholesterol and triglycerides. AIM We wished to test the hypothesis that high-viscosity (HV) and low-viscosity preparations of barley and oat beta-glucan modify the expression of selected genes of lipid-binding proteins in the intestinal mucosa and reduce the intestinal in vitro uptake of lipids. METHODS Five different beta-glucan extracts were separately added to test solutions at concentrations of 0.1-0.5% (wt/wt), and the in vitro intestinal uptake of lipids into the intestine of rats was assessed. An intestinal cell line was used to determine the effect of beta-glucan extracts on the expression of intestinal genes involved in lipid metabolism and fatty acid transport. RESULTS All extracts reduced the uptake of 18:2 when the effective resistance of the unstirred water layer was high. When the unstirred layer resistance was low, the HV oat beta-glucan extract reduced jejunal 18:2 uptake, while most extracts reduced ileal 18:2 uptake. Ileal 18:0 uptake was reduced by the HV barley extract, while both jejunal and ileal cholesterol uptakes were reduced by the medium-purity HV barley extract. The inhibitory effect of HV barley beta-glucan on 18:0 and 18:2 uptake was more pronounced at higher fatty acid concentrations. The expression of genes involved in fatty acid synthesis and cholesterol metabolism was down-regulated with the HV beta-glucan extracts. beta-Glucan extracts also reduced intestinal fatty-acid-binding protein and fatty acid transport protein 4 mRNA. CONCLUSIONS The reduced intestinal fatty acid uptake observed with beta-glucan is associated with inhibition of genes regulating intestinal uptake and synthesis of lipids. The inhibitory effect of beta-glucan on intestinal lipid uptake raises the possibility of their selective use to reduce their intestinal absorption.