Biomedical subjects

F Shahidi

Publications and source records attributed to F Shahidi.

At least 19 recordsLinked to original sources

PubMed2006

Effects of hazelnut-enriched diet on plasma cholesterol and lipoprotein profiles in hypercholesterolemic adult men.

OBJECTIVE: Frequent consumption of nuts is associated with favorable plasma lipid profiles and reduced risk of coronary heart disease (CHD). This study was conducted to investigate the effects of hazelnut-enriched diet on plasma cholesterol and lipoprotein profiles in hypercholesterolemic adult men compared with baseline and control diet, and also to measure the anthropometric parameters, habitual physical activities, nutrient intake and endothelial function. SUBJECTS AND DESIGN: Fifteen hypercholesterolemic men aged 48+/-8 years were recruited voluntarily. A well-controlled, 2-period (P1 and P2) study design with a total of 8-week was implemented. In the P1, subjects consumed a control diet (low-fat, low-cholesterol and high-carbohydrate). During the P2, the control diet was supplemented with MUFA-rich hazelnut (40 g/day), which provided 11.6% of total energy content. Anthropometric parameters and habitual physical activities were recorded. Plasma total and HDL cholesterol, TAG, ApoA-1, Apo B, total homocysteine and glucose concentrations were measured. All parameters and measurements were obtained at baseline and end of each 4-week diet period. RESULTS: Body weights of subjects remained stable throughout the study. Compared with baseline, the hazelnut-enriched diet decreased (P<0.05) the concentrations of VLDL cholesterol, triacylglycerol, apolipoprotein B by 29.5, 31.8, and 9.2%, respectively, while increasing HDL cholesterol concentrations by 12.6%. Total/HDL cholesterol and LDL/HDL cholesterol ratios favorably decreased (P<0.05). Although insignificant there was a decreasing trend for the rest of parameters, particularly in total (5.2%) and LDL cholesterol (3.3%) in subjects consuming a hazelnut-enriched diet compared to that of the baseline. No changes were found in fasting levels of glucose, Apo A-1 and homocysteine between the control and hazelnut-enriched diets. CONCLUSIONS: This study demonstrated that a high-fat and high-MUFA-rich hazelnut diet was superior to a low-fat control diet because of favorable changes in plasma lipid profiles of hypercholesterolemic adult men and, thereby positively affecting the CHD risk profile. SPONSORSHIP: Funding provided by a grant from the Hazelnut Promotion Group, Giresun, Turkey.

Anthropometry↗

PubMed2001

Headspace volatile aldehydes as indicators of lipid oxidation in foods.

Aldehydes are secondary breakdown products of unsaturated lipids. In particular, polyunsaturated lipid fatty acids of the omega-6 and omega-3 families are highly susceptible to oxidation. Using static headspace analysis, the specific aldehyde markers were studied. While linoleic, gamma-linolenic and arachidonic acids found in different foods were precursors of hexanal, propanal was the dominant aldehyde formed from the breakdown of alpha-linolenic, eicosapentaenoic and docosahexaenoic acids. Thus, use of selected aldehydes for monitoring oxidation of food lipids is recommended.

Aldehydes↗

PubMed2001

Isolation and characterization of antioxidative peptides from gelatin hydrolysate of Alaska pollack skin.

Gelatin extracted from Alaska pollack skin was hydrolyzed with serial digestions in the order of Alcalase, Pronase E, and collagenase using a three-step recycling membrane reactor. The fraction from the second step, which was hydrolyzed with Pronase E, was composed of peptides ranging from 1.5 to 4.5 kDa and showed high antioxidative activity. Two different peptides showing strong antioxidative activity were isolated from the hydrolysate using consecutive chromatographic methods including gel filtration on a Sephadex G-25 column, ion-exchange chromatography on a SP-Sephadex C-25 column, and high-performance liquid chromatography on an ODS column. The isolated peptides, P1 and P2, were composed of 13 and 16 amino acid residues, respectively; and both peptides contained a Gly residue at the C-terminus and the repeating motif Gly-Pro-Hyp. The antioxidative activities of the purified peptides were measured using the thiobarbituric acid method, and the cell viability was measured with MTT assay. The results showed that P2 had potent antioxidative activity on peroxidation of linoleic acid. Moreover, the cell viability of cultured liver cells was significantly enhanced by addition of the peptide. These results indicate that the purified peptide, P2, from gelatin hydrolysate of Alaska pollack skin is a natural antioxidant which has potent antioxidative activity.

Animals↗

PubMed2001

Nutrient distribution and phenolic antioxidants in air-classified fractions of beach pea (Lathyrus maritimus L.).

Beach pea (Lathyrus maritimus L.) cotyledons and hulls were air-classified into different fractions. The crude protein content (%N x 6.25) of samples ranged from 32.8 to 35.3% in cotyledons and 14.7 to 16.8% in hulls. Crude fiber content was higher in hulls fraction 1 (37.13%) and fraction 2 (36.85%) than in cotyledons (2.83, 2.99, and 3.08% in fractions 1, 2, and 3, respectively). Condensed tannins of cotyledons ranged from 5.76 to 6.90% and of hulls ranged from 52.49 to 57.24%, expressed as catechin equivalents. Minerals, namely P, K, and Zn, were higher in cotyledons, but Ca and Mn were more prevalent in hulls. Nonprotein nitrogen was concentrated in hulls, whereas phytic acid was more abundant in the cotyledons. The UV absorption pattern showed that flavonoids were present in fractions (I-III) from hulls separated on Sephadex LH-20. Fraction III from hulls had the highest content of total phenolics and condensed tannins, but no condensed tannins were detected in fractions I and II from hulls. The antioxidant activity of fractions separated on Sephadex LH-20 from hulls and crude extracts in a beta-carotene-linoleate model system was in the order of fraction III > crude extract > fraction II > fraction I. Spots on silica gel TLC plates, sprayed with a solution of beta-carotene and linoleic acid, indicated that many of the individual compounds were antioxidative in nature. Further, separation of fraction III from hulls on a semipreparative HPLC showed the presence of (+) catechin and (-) epicatechin as the main low-molecular-weight phenolic compounds present.

Antioxidants↗

PubMed2001

Comparison of volatiles, phenolics, sugars, antioxidant vitamins, and sensory quality of different colored carrot varieties.

Four different colored carrots, orange, purple with orange core, yellow, and white, were examined for their content of phenolics, antioxidant vitamins, and sugars as well as their volatiles and sensory responses. A total of 35 volatiles were identified in all carrots, 27 positively. White carrot contained the highest content of volatiles, followed by orange, purple, and yellow. In total, 11, 16, 10, and 9 phenolic compounds were determined for the first time in orange, purple, yellow, and white carrots, respectively. Of these, chlorogenic acid was the most predominant phenolic compound in all carrot varieties. Differences (p < 0.05) in relative sweetness, the contents of vitamin C and alpha- and beta-carotenes, and certain flavor characteristics were observed among the colored carrot varieties examined. Purple carrots contained 2.2 and 2.3 times more alpha- and beta-carotenes (trace in yellow; not detected in white) than orange carrots, respectively. Purple carrot may be used in place of other carrot varieties to take advantage of its nutraceutical components.

Antioxidants↗

PubMed2001

Angiotensin I converting enzyme inhibitory peptides purified from bovine skin gelatin hydrolysate.

Bovine skin gelatin was hydrolyzed with sequential protease treatments in the order of Alcalase, Pronase E, and collagenase using a three-step ultrafiltration membrane reactor. The molecular weight distributions of the first, second, and third hydrolysates were 4.8-6.6, 3.4-6.6, and 0.9-1.9 kDa, respectively. The angiotensin I converting enzyme (ACE) inhibitory activity of the third hydrolysate (IC(50) = 0.689 mg/mL) was higher than that of the first and second hydrolysates. Two different peptides showing strong ACE inhibitory activity were isolated from the hydrolysate using consecutive chromatographic methods including gel filtration chromatography, ion-exchange chromatography, and reversed-phase high-performance liquid chromatography. The isolated peptides were composed of Gly-Pro-Leu and Gly-Pro-Val and showed IC(50) values of 2.55 and 4.67 microM, respectively.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2000

Antioxidants in food and food antioxidants.

Antioxidants may be present in foods as endogenous factors or may be added to preserve their lipid components from quality deterioration. Synthetic antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate (PG) and tert-butylhydroquinone (TBHQ) are commonly used in food formulations. However, due to safety concerns, interest in natural antioxidants has intensified. To address the demand by consumers, mixed tocopherols, herbal extracts such as those of rosemary and sage, as well as tea extracts have been commercialized for food and nutraceutical applications. An overview of the topic is provided in this article.

Antioxidants↗

PubMed2000

Antioxidant factors in plant foods and selected oilseeds.

The effect of dietary factors on health promotion and disease prevention has been an issue of interest since antiquity and has become a subject of renewed research activity in recent years. Many of the components involved are antioxidative in nature and include phenolic compounds. These phenolics exist in the free, esterified, glycosylated and polymeric forms. Scrutiny of the source materials, their subsequent extraction under optimized conditions and evaluation of activity, followed by fractionation and structure elucidation of active components is generally necessary. Meals obtained from oilseeds, such as canola, mustard, flax, borage, and evening primrose, after oil extraction, contained a variety of antioxidative factors. The antioxidative effect of source materials, their extracts or fractions thereof, depended on the seed type, the content and chemical nature of their active components.

Antioxidants↗

PubMed2000

Insoluble condensed tannins of canola/rapeseed.

The contents of soluble, SDS-extractable, and insoluble condensed tannins were determined in canola/rapeseed hulls from several varieties by utilizing the proanthocyanidin assay. The total amount of tannins in rapeseed/canola hulls ranged from 1913 to 6213 mg per 100 g of oil-free hulls. Insoluble tannins predominated in canola/rapeseed hulls and comprised from 70 to 95.8% of total tannins present. The amounts of SDS-extractable tannins were comparable to those of soluble tannins but constituted only 4.7-14. 1% of insoluble tannins present.

Anthocyanins↗

PubMed2000

Antioxidant activity of various fractions of non-tannin phenolics of canola hulls.

Cyclone canola hulls were extracted with 70% (v/v) acetone. The dried crude extract was dissolved in ethanol and fractionated on a Sephadex LH-20 column using 95% (v/v) ethanol as the mobile phase. Five major fractions were isolated according to the UV absorption. All fractions exhibited marked antioxidant activity in a beta-carotene-linoleate model system. Fractions I and II showed the best preventive effect against the bleaching of beta-carotene. The scavenging effect of fractions I, III, and V, at 1 mg, on alpha, alpha-diphenyl-beta-picrylhydrazyl (DPPH) radical was 67.4%, 80.7%, and 63.3%, respectively. Fractions II and IV showed weak DPPH scavenging effects. The reducing power of phenolics present in fractions IV and V was greater than that of fractions I-III, and the observed data correlated well (r(2) = 0.937; P = 0.007) with the total content of phenolics present in each fraction.

Antioxidants↗

PubMed1999

Novel chemicals from plants via bioengineering. An overview.

Novel chemicals were traditionally extracted from medicinal plants or produced synthetically. However, new development in the field of bioengineering has allowed production of novel products from plants such as edible and industrial oils as well as specific chemicals which could be used as foods with remedial effects.

Bioreactors↗

PubMed1999

Evening primrose meal: a source of natural antioxidants and scavenger of hydrogen peroxide and oxygen-derived free radicals.

Evening primrose meal (EPM: 1% and 2%, w/w) reduced (p </= 0.05) the formation of 2-thiobarbituric acid-reactive substances (TBARS), hexanal, and total volatiles in cooked comminuted pork by 43.6-72.6%. Phenolic compounds in the EPM were extracted under optimum conditions (with 56% acetone at 71 degrees C for 47 min) predicted by a multivariate analysis. The resulting evening primrose crude extract (EPCE) inhibited the bleaching of beta-carotene in a model system. After 2 h of assay, the system containing 200 ppm EPCE [as (+)catechin equivalents] retained 86% of the initial beta-carotene whereas the control retained only 11%. Inhibition of the formation of TBARS, hexanal, and total volatiles in the cooked comminuted pork containing 200 ppm EPCE [as (+)catechin equivalents] ranged from 67. 3% to 97.5%. The EPCE inhibited the formation of conjugated dienes, hexanal, and total volatiles in stripped-bulk corn oil (18.5-63.6% inhibition) and stripped-corn oil-in-water emulsion systems (31.7-65. 6% inhibition). Hydrogen peroxide (H(2)O(2)), hydroxyl radical ((*)OH), and superoxide radical (O(2)(*)(-)) scavenging properties of the EPCE were comparable to those observed for authentic (+)catechin. At 200 ppm of the EPCE [as (+)catechin equivalents], a 100% quenching of (*)OH and O(2)(*)(-) was evident. The EPCE scavenged 44-91% of H(2)O(2) in the assay medium after 10 min as compared to 7% reduction in the control.

Animals↗

PubMed1999

Enzyme-assisted acidolysis of borage (Borago officinalis L.) and evening primrose (Oenothera biennis L.) oils: incorporation of omega-3 polyunsaturated fatty acids.

Lipase-catalyzed acidolysis of borage (Borago officinalis L.) and evening primrose (Oenothera biennisL.) oils with long-chain omega3 polyunsaturated fatty acids (PUFA), namely, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, was carried out in hexane, and the products were analyzed using gas chromatography. The most effective lipase for incorporation of omega3 PUFA into these oils was Pseudomonas sp. as compared to lipases from Mucor miehei and Candida antarctica. Response surface methodology was used to obtain a maximum yield of EPA+DHA incorporation while using the minimum amount of enzyme possible. The process variables studied were the amount of enzyme (150-350 units), reaction temperature (30-60 degrees C), and reaction time (6-30 h). All experiments were carried out according to a face-centered cube design. Under optimum conditions, incorporation of EPA+DHA was 35.5% in borage oil and 33. 6% in evening primrose oil. The modified borage and evening primrose oils containing gamma-linolenic acid, EPA, and DHA were successfully produced and may have potential health benefits.

Catalysis↗

PubMed1998

Process-induced chemical changes in foods. An overview.

Processing of foods induces changes in their physical, chemical and sensory characteristics. Many researchers have shown the chemical consequences of food processing on acceptability and sensory attributes, nutritive value and wholesomeness of foods. A cursory account of these changes is provided.

Dietary Carbohydrates↗

PubMed1998

Process-induced changes in edible oils.

Lipids are one of the main dietary components that serve several functions in foods and nutrition. They could be endogenous or deliberately included in food. The basic molecules of lipids undergo different chemical reactions during refining, processing and storage. Some of these chemical reactions enhance the usage and functionality of food lipids. This chapter discusses the chemical changes of lipids during various processing operations. Specific changes in the minor constituents of lipids are also included.

Alkalies↗

PubMed1998

Process-induced compositional changes of flaxseed.

Flaxseed has been used as an edible grain in different parts of the world since ancient times. However, use of flaxseed oil has been limited due to its high content of polyunsaturated fatty acids. Nonetheless, alpha-linolenic acid, dietary fiber and lignans of flaxseed have regained attention. New varieties of flaxseed containing low levels of alpha-linolenic acid are available for edible oil extraction. Use of whole flaxseed in foods provides a means to utilise all of its nutrients and require minimum processing steps. However, the presence of cyanogenic glucosides and diglucosides in the seeds is a concern as they may release cyanide upon hydrolysis. In addition, the polyunsaturated fatty acids may undergo thermal or autooxidation when exposed to air or high temperatures that are used in food preparation. Studies todate on oxidation products of intact flaxseed lipids have not shown any harmful effects when flaxseed is included, up to 28%, in the baked products. Furthermore, cyanide levels produced as a result of autolysis are below the harmful limits to humans. However, the meals left after oil extraction require detoxification but, by solvent extraction, to reduce the harmful effects of cyanide when used in animal rations. Flaxseed meal is a good source of proteins; these could be isolated by complexation with sodium hexametaphosphate without changing their nutritional value or composition. In addition, the effect of germination on proteins, lipids, cyanogenic glycosides, and other minor constituents of flaxseed is discussed.

Amino Acids↗

PubMed1998

Carotenoid pigments in seafoods and aquaculture.

Color plays a major role in the overall acceptability of food products. It is considered one of man's basic experiences that a particular foodstuff has to be of a distinct color in order to be edible. The color of a seafood is the first characteristic noted by the consumer and is directly related to the subsequent acceptance or rejection of it. Carotenoids contribute to the yellow, orange, and red colors of the skin, shell, or exoskeleton of aquatic animals. Indeed, they are the most widespread pigments found in nature, as they occur in bacteria, yeasts, mold, all green plants, and many animals, and therefore various functions have been attributed to them. From anthropocentric consideration, the most significant aspect of carotenoids is the color they impart to our food and environment. In animals, the carotenoids are also associated with reproductive organs and hence the hatching success and survival of alevins.

Animals↗

PubMed1997

Unraveling the chemical identity of meat pigments.

This review examines the chemistry of nitrite curing of meat and meat products as it relates to the development of cured meat color and provides a detailed account of how nitrite-free processed meats could be prepared using the preformed cooked cured-meat pigment (CCMP). Thus, a chemical description of meat color, both raw and cooked, and characterization of nitrosylheme pigments follows. Based on electron paramagnetic resonance (EPR), visible and infrared spectroscopic studies, evidence has been provided to support the hypothesis that the chemical structure of the preformed CCMP is identical to that of the pigment prepared in situ after thermal processing of nitrite-cured meat and is in fact a mononitrosylheme complex. An appendix, which describes the basic principles of EPR spectroscopy used in the context of this review, is attached.

Animals↗