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1.
Food Chem ; 278: 644-652, 2019 Apr 25.
Article in English | MEDLINE | ID: mdl-30583424

ABSTRACT

Isoelectric solubilization/precipitation (ISP) was used to extract krill protein isolate (KPI). Due to krill endogenous proteases ISP-KPI barely forms gel which is a major hurdle in wide application of this tremendous protein source for direct human consumption. The objective was to improve gelation and elucidate interaction mechanism between κ-carrageenan and KPI. κ-Carrageenan was added to KPI at 0.00, 0.75, 1.50, 2.25, and 3.00 g/150 g and heated at 90 °C for 15 min. Added κ-carrageenan improved texture of KPI gels. However, the level of addition had minimal effect. SDS-PAGE revealed severe proteolysis of KPI even during heating. Total and free sulfhydryl were not different, while surface hydrophobicity and water-holding-capacity slightly decreased and increased, respectively with added κ-carrageenan. Fourier-transform-infrared-spectroscopy showed none-to-minimal shift of ß-sheet and α-helical protein structure; while CC and CO stretching as well as CH bending of κ-carrageenan showed the greatest shift, indicating that κ-carrageenan was mainly responsible for gel formation.


Subject(s)
Carrageenan/chemistry , Euphausiacea/chemistry , Gels/chemistry , Proteins/chemistry , Animals , Euphausiacea/metabolism , Hydrophobic and Hydrophilic Interactions , Protein Structure, Tertiary , Spectroscopy, Fourier Transform Infrared , Temperature , Water/chemistry
2.
J Food Sci ; 83(7): 1970-1979, 2018 Jul.
Article in English | MEDLINE | ID: mdl-29846939

ABSTRACT

The objective of this study was to evaluate the nutritional quality and physical characteristics of soluble proteins separated from silver carp at 4, 20, and 40 °C. Ground silver carp was diluted, and soluble proteins were separated by centrifugation and dried. The proximate composition (dry wt) of the protein powders averaged 82.42% protein, 3.25% lipid, and 14.50% ash. Average protein recovery yield was 11.78% with the better yields occurring at 20 °C (P < 0.05). Mineral profile revealed greater concentrations of Fe, Mg, P, and Na when compared to the initial homogenate. More saturated and monounsaturated fatty acids were recovered in the 4 °C powder and the least in the 40 °C powder (P < 0.05). Polyunsaturated fatty acids displayed a reverse trend, with the greatest concentration in the 40 °C powder and the least in the 4 °C powder (P < 0.05). The amino acid profile revealed that the protein powder met all FAO/WHO/UNO amino acid requirements for adults. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed high amounts of low and medium molecular weight (MW) proteins (10-15 and 25-50 kDa, respectively). Two-dimensional (2-D) electrophoresis indicated that the low MW proteins possessed a neutral isoelectric point relative to that of the medium MW proteins. The protein powder was significantly less soluble (P < 0.05) than whey protein concentrate 80 at every pH tested (pH 3.0 to 11.0). Similar tendencies were seen when ionic strength was shifted (0.0 to 1.1 I; P < 0.05). Soluble protein powders derived from silver carp are nutrient rich and have physical characteristics resembling whey protein concentrate. Changes in process temperature had limited effects on protein powder composition. PRACTICAL APPLICATION: Soluble proteins contribute to 20 to 40% of fish protein and are soluble in neutral salt solutions. Much of the sarcoplasmic proteins are lost when they solubilize in processing water and are discarded similarly to how whey protein was once discarded during dairy processing. When government regulations on whey disposal were implemented, the dairy industry responded by repurposing the high-quality protein for human use and it is now a billion dollar industry. The aim of this research project was to verify the composition of an otherwise overlooked protein source.


Subject(s)
Fish Proteins/chemistry , Adult , Amino Acids/chemistry , Animals , Carps , Electrophoresis, Polyacrylamide Gel , Humans , Lipids/chemistry , Nutritive Value , Powders/chemistry , Solubility , Whey Proteins/analysis
3.
J Sci Food Agric ; 98(9): 3452-3461, 2018 Jul.
Article in English | MEDLINE | ID: mdl-29283436

ABSTRACT

BACKGROUND: Egg sticks fortified with omega-3 polyunsaturated fatty acids (ω-3 PUFAs) were developed by replacing egg yolk with salmon, algae, and flax oils. Egg sticks were cooked before analysis. Quality indicators for storage stability under different packaging and temperature were determined throughout a 28-day storage. Egg sticks were vacuum and non-vacuum packed. Further, both packaging treatments were divided into two storage temperatures of 4 and 10 °C. Quality indicators were determined every 7 days, including pH, syneresis, texture, color, microbial growth, proximate composition, fatty acid profile, and lipid oxidation. RESULTS: Vacuum-packed egg sticks stored at 4 °C had slower degradation over time than all other treatments; however, they also had higher syneresis, harder texture, and higher anaerobic growth. Although vacuum packaging slowed lipid oxidation, it had limited effect on prevention of ω-3 PUFAs degradation; whereas refrigeration (4 °C) seemed to prevent degradation of ω-3 PUFAs better than it could slow lipid oxidation. CONCLUSION: Based on the results, it can be concluded that both vacuum packaging and refrigeration at 4 °C decrease degradation of egg sticks developed in the present study during storage. Under these conditions, egg sticks may maintain stability for at least 21 days of storage. © 2017 Society of Chemical Industry.


Subject(s)
Eggs , Fatty Acids, Omega-3 , Food Preservation/methods , Animals , Egg White , Egg Yolk , Eggs/microbiology , Fatty Acids/analysis , Fish Oils , Food Packaging/methods , Food, Fortified , Functional Food , Hydrogen-Ion Concentration , Linseed Oil , Lipid Peroxidation , Refrigeration , Salmon , Sensation , Vacuum
4.
Food Sci Nutr ; 5(3): 763-769, 2017 05.
Article in English | MEDLINE | ID: mdl-28572966

ABSTRACT

Calcium-enhanced protein recovered from black bullhead catfish was used to develop gels containing increasing amounts of potato starch (0-20 g/kg protein paste) and the effects of starch on functional, textural, and color properties were tested. Energy required to unfold protein groups was greater with the addition of 5 g starch/kg protein paste. Gels containing starch were harder, chewier, and less springy (p < .05) than gels without starch. For most measurements, regression analysis showed that increasing the starch concentration beyond 5 g/kg did not contribute to further significant textural changes. Torsional shear stress and strain along with Kramer shear force increased as the concentration of starch increased (R2  = .79, .79, and .53, respectively). The addition of ≥10 g starch/kg protein paste resulted in darker gels and gels got darker as more starch was added (R2  = .71). Results showed no benefit to increasing starch concentration in gels beyond 5 g starch/kg protein paste.

5.
J Sci Food Agric ; 97(3): 811-817, 2017 Feb.
Article in English | MEDLINE | ID: mdl-27185206

ABSTRACT

BACKGROUND: Protein may be recovered by using pH shifts to solubilize and precipitate protein. Typically, sodium hydroxide is used as the processing base; however, this has been shown to significantly increase sodium in the final recovered protein. RESULTS: Protein was extracted from black bullhead catfish (Ameiurus melas) using a pH-shift method. Protein was solubilized using either sodium hydroxide (NaOH) or calcium hydroxide (Ca(OH)2 ) and precipitated at pH 5.5 using hydrochloric acid (HCl). Protein solubility was greater when Ca(OH)2 was used compared to NaOH during this process. Using Ca(OH)2 as the processing base yielded the greatest lipid recovery (P < 0.05) at 77 g 100 g-1 , whereas the greatest (P < 0.05) protein recovery yield was recorded as 53 g 100 g-1 protein using NaOH. Protein solubilized with Ca(OH)2 had more (P < 0.05) calcium in the protein fraction, whereas using NaOH increased (P < 0.05) sodium content. CONCLUSION: Results of our study showed that protein solubility was increased and the recovered protein had significantly more calcium when Ca(OH)2 was used as the processing base. Results showed both NaOH and Ca(OH)2 to be an effective processing base for pH-shift protein recovery processes. © 2016 Society of Chemical Industry.


Subject(s)
Calcium Hydroxide/chemistry , Dietary Proteins/isolation & purification , Fish Products/analysis , Fish Proteins/isolation & purification , Food Additives/chemistry , Ictaluridae , Animals , Calcium, Dietary/analysis , Chemical Precipitation , Dietary Fats/analysis , Dietary Proteins/chemistry , Fish Proteins/chemistry , Fisheries , Food Handling , Food Packaging , Food Storage , Humans , Hydrochloric Acid/chemistry , Hydrogen-Ion Concentration , Nutritive Value , Sodium Hydroxide/chemistry , Solubility , Vacuum , West Virginia
6.
J Sci Food Agric ; 96(1): 280-6, 2016 Jan 15.
Article in English | MEDLINE | ID: mdl-25641161

ABSTRACT

BACKGROUND: Gelation conditions affect the setting of myofibrillar fish protein gels. Therefore the impact of widely applied pre-cooking gelation time/temperature strategies and post-cooking period on the texture and color of final protein gels was determined. Four pre-cooking gelation strategies (no setting time, 30 min at 25 °C, 1 h at 40 °C or 24 h at 4 °C) were applied to protein pastes (fish protein concentrate and standard functional additives). After cooking, texture and color were analyzed either directly or after 24 h at 4 °C on gels adjusted to 25 °C. RESULTS: No-set gels were harder, gummier and chewier (P < 0.05) when analyzed immediately after cooling; however, gel chewiness, cohesiveness and firmness indicated by Kramer force benefited from 24 h at 4 °C gel setting when stored post-cooking. Gel-setting conditions had a greater (P < 0.05) effect on texture when directly analyzed and most changes occurred in no-set gels. There were significant (P < 0.05) changes between directly analyzed and post-cooking stored gels in texture and color, depending on the pre-cooking gelation strategy. CONCLUSION: Pre-cooking gelation conditions will affect final protein gel texture and color, with gel stability benefiting from a gel-setting period. However, post-cooking storage may have a greater impact on final gels, with textural attributes becoming more consistent between all samples.


Subject(s)
Color , Fish Products/analysis , Fish Proteins/chemistry , Food Handling/methods , Hardness , Temperature , Cooking , Food Storage , Gels , Humans , Hydrogen-Ion Concentration
7.
J Sci Food Agric ; 95(2): 275-80, 2015 Jan.
Article in English | MEDLINE | ID: mdl-24777972

ABSTRACT

BACKGROUND: Isoelectric solubilization and precipitation (ISP) processing uses pH shifts to separate protein from fish frames, which may increase commercial interest for silver carp. Texture and color properties of gels made from silver carp protein recovered at different pH strategies and organic acid types were compared. ISP was applied to headed gutted silver carp using 10 mol L(-1) sodium hydroxide (NaOH) and either glacial acetic acid (AA) or a (1:1) formic and lactic acid combination (F&L). Protein gels were made with recovered protein and standard functional additives. RESULTS: Texture profile analysis and the Kramer shear test showed that protein gels made from protein solubilized at basic pH values were firmer, harder, more cohesive, gummier and chewier (P < 0.05) than proteins solubilized under acidic conditions. Acidic solubilization led to whiter (P < 0.05) gels, and using F&L during ISP yielded whiter gels under all treatments (P < 0.05). CONCLUSION: Gels made from ISP-recovered silver carp protein using organic acids show potential for use as a functional ingredient in restructured foods.


Subject(s)
Acids , Carps , Dietary Proteins/chemistry , Fish Products/analysis , Fish Proteins/chemistry , Food Handling , Food Quality , Acetic Acid , Animals , Chemical Precipitation , Color , Consumer Behavior , Cooking , Diet , Formates , Gels/chemistry , Hardness , Humans , Hydrogen-Ion Concentration , Lactic Acid , Muscle Proteins/chemistry , Solubility
8.
Food Chem ; 148: 70-6, 2014 Apr 01.
Article in English | MEDLINE | ID: mdl-24262528

ABSTRACT

Although dietary fiber provides health benefits, most Western populations have insufficient intake. Surimi seafood is not currently fortified with dietary fiber, nor have the effects of fiber fortification on physicochemical properties of surimi been thoroughly studied. In the present study, Alaska pollock surimi was fortified with 0-8 g/100 g of long-chain powdered cellulose as a source of dietary fiber. The protein/water concentrations in surimi were kept constant by adding an inert filler, silicon dioxide in inverse concentrations to the fiber fortification. Fiber-fortified surimi gels were set at 90 °C. The objectives were to determine (1) textural and colour properties; (2) heat-induced gelation (dynamic rheology); and (3) protein endothermic transitions (differential scanning calorimetry) of surimi formulated with constant protein/water, but variable fiber content. Fiber fortification up to 6 g/100 g improved (P<0.05) texture and colour although some decline occurred with 8 g/100g of fiber. Dynamic rheology correlated with texture and showed large increase in gel elasticity, indicating enhanced thermal gelation of surimi. Differential scanning calorimetry showed that fiber fortification did not interfere with thermal transitions of surimi myosin and actin. Long-chain fiber probably traps water physically, which is stabilized by chemical bonding with protein within surimi gel matrix. Based on the present study, it is suggested that the fiber-protein interaction is mediated by water and is physicochemical in nature.


Subject(s)
Dietary Fiber/analysis , Fish Products/analysis , Food, Fortified/analysis , Gels/chemistry , Animals , Calorimetry, Differential Scanning , Food Additives/chemistry , Gadiformes , Rheology
9.
Food Chem ; 149: 208-14, 2014 Apr 15.
Article in English | MEDLINE | ID: mdl-24295697

ABSTRACT

Infant milk formula has recently been implicated as a transmission vehicle for an emerging foodborne pathogen, Enterobacter sakazakii, resulting in high mortality rates. Electron beam (e-beam) efficiently and non-thermally inactivates foodborne pathogens, including E. sakazakii, in infant milk formula. However, the effects of e-beam on chemical changes of nutrients in infant formula have not been determined. Therefore, the objective of this study was to fulfill this gap. Dehydrated infant milk formula was processed with e-beam at 0 (control) to 25 kGy. Amino acid, fatty acid, and mineral profiles (AAP, FAP, and MP, respectively), as well as protein degradation and lipid oxidation, were determined. There were no differences (P>0.05) in FAP, AAP, and MP. SDS-PAGE electrophoresis qualitatively detected three major protein bands in all samples up to 25 kGy. Densitometry analysis of SDS-PAGE gels confirmed no size degradation (P>0.05) as a function of increased e-beam dose. Totol-volatile-basic-nitrogen (TVBN) excluded (P>0.05) protein degradation due to microbial activity. There was no increase (P>0.05) in lipid oxidation, as assessed with thiobarbituric-reactive-substances (TBARS), except in samples processed at 25 kGy. Dehydrated formula has low water activity, which likely protected nutrients from e-beam-induced chemical changes. This study demonstrates that proteins, lipids, and minerals in infant milk formula are stable when processed with e-beam up to 25 kGy at low temperature and under anaerobic conditions.


Subject(s)
Food Irradiation/methods , Infant Food/radiation effects , Infant Formula/chemistry , Amino Acids/analysis , Fatty Acids/analysis , Food Irradiation/instrumentation , Gamma Rays , Infant Food/analysis , Minerals/analysis , Nutritive Value/radiation effects , Proteins/analysis
10.
Food Chem ; 139(1-4): 777-85, 2013 Aug 15.
Article in English | MEDLINE | ID: mdl-23561173

ABSTRACT

Protein isolate was recovered from whole gutted fish using isoelectric solubilisation/precipitation (ISP). The objective was to determine chemical properties of heat-set gels made of the ISP protein isolate fortified with ω-3 polyunsaturated fatty acids (PUFAs)-rich oils (flaxseed, fish, algae, krill, and blend). The extent of the PUFAs increase, ω-6/ω-3 FAs and unsaturated/saturated FAs ratios, and the indices of thrombogenicity and atherogenicity depended on specific ω-3 PUFAs-rich oil used to fortify protein isolate gels. Lipid oxidation in ω-3 PUFAs fortified gels was minimal, although greater (P<0.05) than control gels (without ω-3 PUFAs fortification). However, all gels were in the slightly rancid, but acceptable range. The commonly used thiobarbituric-acid-reactive-substances (TBARS) assay to determine lipid oxidation in seafood may be inaccurate for samples containing krill oil due to its red pigment, astaxanthin. Protein degradation (total-volatile-basic-nitrogen) was greater (P<0.05) in ω-3 PUFAs fortified gels than control gels. However, all gels were considerably below the acceptability threshold for protein degradation. The shear stress of ω-3 PUFAs fortified gels was generally greater than the control gels and the shear strain was generally unchanged. This study demonstrates that ω-3 PUFAs fortification of protein isolates recovered with ISP from fish processing by-products or whole fish has potential application in the development of functional foods.


Subject(s)
Fatty Acids, Omega-3/analysis , Fish Products/analysis , Fish Proteins/chemistry , Functional Food/analysis , Animals , Chemical Precipitation , Fish Proteins/isolation & purification , Fishes , Food Handling , Gels/chemistry , Lipids/chemistry , Oxidation-Reduction , Protein Hydrolysates/chemistry , Protein Hydrolysates/isolation & purification , Solubility
11.
J Food Sci ; 78(3): E445-51, 2013 Mar.
Article in English | MEDLINE | ID: mdl-23458747

ABSTRACT

UNLABELLED: Protein was recovered from headed gutted silver carp by isoelectric solubilization at pH 2.5, 3.0, 11.5, or 12.0 and precipitation (ISP) at pH 5.5 using acetic (AA) or a 30% formic and lactic acid combination (F&L) and 10 N sodium hydroxide. Total protein and fat recovery yields, proximate composition and mineral analyses of fractions were determined. Protein and lipid recovery yields when solubilized under basic conditions were comparable to yields reported from other studies using hydrochloric acid; however, the recovered fractions were less pure. Processing at basic pH using AA was more effective than F&L at removing impurities (P < 0.05) from the recovered protein fraction and impurities were effectively removed from recovered lipids regardless of processing pH or acid type (P > 0.05). For the most part, sodium was greater (P < 0.05) and there was less calcium, phosphorus, magnesium, and iron (P < 0.05) in the recovered protein regardless of acid used when compared to the initial paste. This research shows that organic acids have the potential to recover protein and lipid by ISP processing. PRACTICAL APPLICATION: This research presents a reliable method for extracting nutritionally valuable fish protein and oils from otherwise hard to process fish and its byproducts. Replacing the traditionally used strong acids with organic acids might further accomplish bacterial load reduction while resulting in similar to or improved protein recovery yields. Therefore, this technology may increase the commercial viability of hard to process fish.


Subject(s)
Carps , Fish Oils/analysis , Fish Proteins/analysis , Food Handling/methods , Animals , Hydrogen-Ion Concentration , Nutritive Value , Solubility , Trace Elements/analysis
12.
J Agric Food Chem ; 60(23): 5979-87, 2012 Jun 13.
Article in English | MEDLINE | ID: mdl-22624700

ABSTRACT

Excessive dietary intake of Na (i.e., NaCl) contributes to hypertension, which is a major risk factor for cardiovascular disease. Normally, NaOH and HCl are used to dissolve and precipitate, respectively, fish muscle proteins in isoelectric solubilization/precipitation (ISP), therefore contributing to increased Na content in the recovered fish protein isolates (FPI). Substitution of NaOH with KOH may decrease the Na content in FPI and, thus, allow development of reduced-Na seafood products. In this study, FPI was recovered with ISP using NaOH or KOH. In order to develop a nutraceutical seafood product, the FPI was extracted with NaCl or KCl-based salt substitute and subjected to cold- or heat-gelation. In addition, standard nutraceutical additives (ω-3 fatty acids-rich oil and dietary fiber) along with titanium dioxide (TiO2) were added to FPI. Color, texture, dynamic rheology, Na and K content, and lipid oxidation of the FPI gels were compared to commercial Alaska pollock surimi gels. FPI gels had greater (p < 0.05) whiteness, good color properties (L*a*b*), and generally better textural properties when compared to surimi gels. Although the ISP-recovered FPI and surimi developed similar final gel elasticity, the proteins in FPI and surimi had different gelation pattern. A reduction (p < 0.05) of Na content and simultaneous increase (p < 0.05) in K content of FPI gels was achieved by the substitution of NaOH with KOH during ISP and NaCl with the KCl-based salt substitute during formulation of the FPI paste. Although cooking and addition of NaCl during formulation of the FPI paste increased (p < 0.05) lipid oxidation in FPI gels, TBARS values were much below rancidity levels. These results indicate that KOH can replace NaOH to recover FPI from whole gutted fish for subsequent development of nutraceutical seafood products tailored for reduction of diet-driven cardiovascular disease.


Subject(s)
Chemical Phenomena , Dietary Supplements/analysis , Fish Products/analysis , Fish Proteins/chemistry , Muscle Proteins/chemistry , Seafood/analysis , Animals , Bass , Chemical Precipitation , Dietary Fiber/analysis , Fatty Acids, Omega-3/analysis , Food Handling , Gadiformes , Gels/chemistry , Hydrogen-Ion Concentration , Solubility , Titanium/analysis
13.
J Sci Food Agric ; 92(12): 2534-42, 2012 Sep.
Article in English | MEDLINE | ID: mdl-22488651

ABSTRACT

BACKGROUND: Skin-on bone-in chicken drumsticks were processed with isoelectric solubilization/precipitation to recover muscle proteins. The drumsticks were used as a model for dark chicken meat processing by-products. The main objective of this study was conversion of dark chicken meat processing by-products to restructured functional food product. An attempt was made to develop functional food product that would resemble respective product made from boneless skinless chicken breast meat. A three-prong strategy to address diet-driven cardiovascular disease (CVD)with a functional food was used in this study. The strategy included addition of three ingredients with well-documented cardiovascular benefits: (i) ω-3 polyunsaturated fatty acid-rich oil (flaxseed-algae, 9:1); (ii) soluble fiber; and (iii) salt substitute. Titanium dioxide, potato starch, polyphosphate, and transglutaminase were also added. The batters were formulated and cooked resulting in heat-set gels. RESULTS: Color (L*a*b*), texture (torsion test, Kramer shear test, and texture profile analysis), thermal denaturation (differential scanning calorimetry), and gelation (dynamic rheology) of chicken drumstick gels and chicken breast gels were determined and compared. Chicken drumstick gels generally had comparable color and texture properties to the gels made from chicken breast meat. The endothermic transition (thermal denaturation) of myosin was more pronounced and gelation properties were better for the drumstick gels. CONCLUSION: This study demonstrated a feasibility to develop functional food made of muscle proteins recovered with isoelectric solubilization/precipitation from low-value dark chicken meat processing by-products. The functional food developed in this study was enriched with CVD-beneficial nutrients and had comparable instrumental quality attributes to respective products made of chicken breast meat. Although the results of this study point towards the potential for a novel, marketable functional food product, sensory tests and storage stability study are recommended.


Subject(s)
Cardiovascular Diseases , Diet , Functional Food/analysis , Meat Products/analysis , Muscle Proteins , Muscle, Skeletal , Animals , Cardiovascular Diseases/prevention & control , Chemical Precipitation , Chickens , Color , Dietary Fats , Dietary Fiber , Dietary Proteins , Fatty Acids, Omega-3 , Flavoring Agents , Gels , Hot Temperature , Humans , Protein Denaturation , Rheology , Solubility , Stress, Mechanical
14.
Int J Radiat Biol ; 87(6): 571-8, 2011 Jun.
Article in English | MEDLINE | ID: mdl-21627563

ABSTRACT

PURPOSE: Electron beam (e-beam) efficiently and non-thermally inactivates microorganisms in food by lethal DNA changes (direct effects) and free radicals from water radiolysis (in-direct effects). Non-pathogenic Escherichia coli DH5α (α substrain of DH5 described by Hanahan 1985 , 'DH' stands for Douglas Hanahan) is a microorganism that lacks DNA repair capability, resulting in high radiosensitivity. Studying microbial inactivation of E. coli DH5α repeatedly subjected to sub-lethal e-beam in ground beef may enhance understanding of microbial radioresistance. The objective of this study was to determine if repetitive processing with e-beam at sub-lethal doses increases D-value (e-beam dose required to inactivate one log of microbial population) of E. coli DH5α in ground beef. MATERIALS AND METHODS: Survivors from the highest e-beam dose were isolated and incubated in ground beef for the next cycle of e-beam processing. Five cycles were conducted. To acclimatise E. coli DH5α, first two cycles used low doses. D-values were determined following the third cycle. RESULTS: D-values increased (p < 0.05) significantly with each cycle. Thus, E. coli DH5α has a capability to develop greater radioresistance under these experimental conditions. Following the third cycle D-values were 0.32 ±â€Š0.006 and 0.32 ±â€Š0.002 kGy for survivors enumerated on non-selective and selective media, respectively; the fourth cycle 0.39 ±â€Š0.007 and 0.40 ±â€Š0.019 kGy; and the fifth cycle 0.46 ±â€Š0.006 and 0.46 ±â€Š0.020 kGy. D-values on non-selective and selective media were similar (p > 0.05) indicating absence of cell recovery in E. coli DH5α. CONCLUSIONS: E. coli DH5α increases radioresistance to e-beam as a result of repetitive exposure to sub-lethal doses despite its DNA repair deficiency.


Subject(s)
DNA Repair , Escherichia coli O157/radiation effects , Food Contamination , Radiation Tolerance , Animals , DNA Repair/radiation effects , Dose-Response Relationship, Radiation , Electrons , Escherichia coli/metabolism , Escherichia coli O157/growth & development , Food Handling/methods , Food Irradiation/methods , Food Microbiology , Free Radicals , Kinetics , Meat , Water/chemistry
15.
J Food Sci ; 76(3): S192-7, 2011 Apr.
Article in English | MEDLINE | ID: mdl-21535859

ABSTRACT

The effects of dietary modification with flaxseed oil-enhanced (Flax) feed on the product quality of brook trout fillets were examined. Trout were fed a commercial feed supplemented with fish oil (CD) or flaxseed oil (Flax) for 165 d before harvesting. Proximate composition and fatty acid profile were determined on fillets. Quality parameters of the raw fillets were examined over the storage period by measuring color (L*, a*, b*), muscle pH, and thiobarbituric acid reactive substances test. Evaluations on the cooked fillets included sensory evaluation with triangle tests and a paired preference test. There were no differences in proximate composition between the groups; however, the total omega-3 fatty acids were greater in Flax fillets (P<0.05). Diet and day were shown to interact in their effect on whiteness, pH, and lipid oxidation (P<0.05); however, linear regression did not determine that malondialdehyde concentration was associated with time in either diet type implying that lipid oxidation in the vacuum-packed fish was controlled at storage temperatures (4°C). Sensory panelists were able to choose the odd sample in a replicated triangle test analyzed using the ß-binomial model, and there was preference for Flax fillets (P<0.05). Results indicate that a Flax-enhanced diet would have favorable effects on product quality of farmed brook trout.


Subject(s)
Aquaculture , Linseed Oil/administration & dosage , Seafood/analysis , Trout , Animal Feed/analysis , Animals , Color , Fatty Acids, Omega-3/administration & dosage , Fatty Acids, Omega-3/analysis , Fish Oils/administration & dosage , Food Handling , Food Preferences , Humans , Hydrogen-Ion Concentration , Malondialdehyde/analysis , Oxidation-Reduction , Quality Control , Random Allocation , Sensation , Taste
16.
Food Chem ; 129(3): 912-9, 2011 Dec 01.
Article in English | MEDLINE | ID: mdl-25212318

ABSTRACT

Surimi-based seafood products are widely accepted and enjoyed worldwide. The US consumption increased in 1980s; however, it leveled thereafter. Food products nutrified with ω-3 polyunsaturated fatty acids (PUFAs) are in increasing demand due to demonstrated health benefits. Currently, surimi seafood is not nutrified with ω-3 PUFAs. In the present study, surimi seafood was nutritionally-enhanced with ω-3 PUFAs-rich oils (flaxseed, algae, menhaden, krill, and blend). The objectives were (1) chemical characterization of FA composition and oxidation, and (2) determination of physicochemical properties (colour and texture) of the nutritionally-enhanced surimi seafood. Oil addition resulted in increased (P<0.05) concentration of total ω-3 FAs in surimi seafood; however, the concentration of α-linolenic (ALA, 18:3ω-3), eicosapentaenoic (EPA, 20:5ω-3) and docosahexaenoic (DHA, 22:6ω-3) acids depended on which oil was added. Although the ω-3 PUFAs nutrification resulted in increased (P<0.05) susceptibility of surimi seafood to lipid oxidation, it was within ranges acceptable to consumers. Texture analysis (texture profile analysis, Kramer shear and torsion test) showed that ω-3 PUFAs nutrification did not affect texture. Colour properties of ω-3 PUFAs nutrified surimi seafood were generally improved except when krill oil or blend was added. This study demonstrates that nutritional value of surimi seafood can be enhanced with concurrent improvement of colour and without affecting texture.

17.
J Food Sci ; 75(7): M462-7, 2010 Sep.
Article in English | MEDLINE | ID: mdl-21535557

ABSTRACT

UNLABELLED: The effect of electron beam (e-beam) radiation on the recovery of Salmonella serotypes Tennessee (ATCC 10722) and Typhimurium (ATCC 14028) in creamy peanut butter over a 14-d storage period at 22 °C was studied. Each Salmonella type was independently inoculated into peanut butter and subjected to e-beam doses that ranged from 0 to 3.1 kGy, confirmed by film dosimetry. After 2-, 4-, 6-, 8-, and 14-d of storage, microbial analyses were conducted. Survivors were recovered on growth and selective media using standard spread-plating methods. Microbial counts (CFU/g) were log-converted and differences were determined by ANOVA and Tukey's Honestly Significant Differences test. When samples were not e-beam-treated, there were no significant changes (P > 0.05) in microbial numbers over time. In e-beamed samples, microbial numbers decreased over time; however, reductions were not always significant. Initial recovery rates (R-rates) 2 d after e-beam treatment were significantly different for the 2 strains of Salmonella and between recovery media (P < 0.05); however, these differences did not persist for the remainder of the storage period (P > 0.05) indicating that injured cells were not able to survive in the high-fat, low-water activity peanut butter environment. R-rates for both strains of Salmonella were maintained until day 14 when there were significant reductions in Salmonella Typhimurium (P < 0.05). These results indicate that Salmonella Tennessee and Salmonella Typhimurium will survive in peanut butter when exposed to nonlethal doses of e-beam irradiation. PRACTICAL APPLICATION: Electron beam (e-beam) irradiation is an alternative to thermal processing; this technique inactivates microorganisms and insects that might be present in a food by generating radiation by accelerated electrons that inactivate organisms directly because of interaction with cell components and indirectly by producing free radicals that disrupt integrity of the cell membrane. E-beam radiation will reduce the number of probable microbiological hazards that could be present while the food remains generally unaffected in texture, taste, and nutritional value. A recent study showed e-beam irradiation to be effective at reducing both Salmonella Tennessee and Typhimurium in peanut butter by one log after exposure to less than 1 kGy, highlighting the need to explore this process further.


Subject(s)
Arachis/microbiology , Condiments/microbiology , Food Irradiation , Salmonella/radiation effects , Seeds/microbiology , Colony Count, Microbial , Food Handling , Food Irradiation/methods , Microbial Viability , Reproducibility of Results , Salmonella/growth & development , Salmonella Food Poisoning/prevention & control , Salmonella typhimurium/growth & development , Salmonella typhimurium/radiation effects , Species Specificity , Time Factors
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