Lebensmittel-Wissenschaft & Technologie, Dec 1, 2021
Abstract Nutritional and functional properties of protein were determined for cricket, locust, an... more Abstract Nutritional and functional properties of protein were determined for cricket, locust, and silk worm pupae powders, specifically macro-nutrient proximate composition, full amino acid composition, protein pH-solubility, and SDS-PAGE/densitometry. Cricket and locust powders contained >70 g of crude protein/100 g of sample powder (d.b. – dry basis), while silk worm pupae powder >50 g of crude protein/100 g of sample powder (d.b.). Insect powders exceeded FAO/WHO/UNU recommendations for eight of the nine essential amino acids (EAAs) for adults, but not infants. Total EAAs (21.8–23.7 g EAAs/100 g sample; d.b.) was two-times higher than FAO/WHO/UNU recommendations for adults (12.7 g EAAs/100 g sample; d.b.), but only half for infants (46.0 g/100 g; d.b.). Nearly 70% of insect protein dissolved in alkaline pH, while only 7% at pH 4–6. SDS-PAGE/densitometry showed four protein fractions: cuticle proteins, actin-arginine kinase, hemocyanin, and myosin. SDS-PAGE/densitometry also showed proteolysis and various distribution of protein fractions among insect powders. Protein may be efficiently isolated from insects using pH-solubility-precipitation; thus, resulting in isolates with high nutritional and functional quality.
Lebensmittel-Wissenschaft & Technologie, Aug 1, 2017
Mass balance analysis was conducted for isoelectric solubilization/precipitation (ISP) processing... more Mass balance analysis was conducted for isoelectric solubilization/precipitation (ISP) processing of carp, chicken, menhaden, and krill based on proximate composition of input materials and recovered fractions (i.e., protein, lipid, insoluble, and process water). Protein recovery yield and lipid reduction were also determined. Thin layer chromatography (TLC) and SDS-PAGE electrophoresis allowed determination of lipid classes and protein electrophoretic patterns. ISP concentrated crude protein (72e90 g/100 g, dry basis) and reduced total lipid (3e16 g/100 g, dry basis) in the protein fraction recovered with ISP when compared to the input materials (48e68 g of crude protein and 15e45 g of total lipid per 100 g, dry basis). Protein recovery yield and lipid reduction were 45e66 and 79e98 g/100 g, respectively. However, lipid fraction did not form when menhaden and krill were processed with ISP. Krill and menhaden lipids were distributed in the process water in addition to the protein and insoluble fractions. TLC showed that krill and menhaden lipids had high phospholipid (PL), but low triglyceride (TAG) content, contributing to emulsification and preventing formation of lipid fraction. SDS-PAGE confirmed presence of myosin and actin in protein fraction recovered from carp and chicken as well as proteolysis in menhaden and severe protein degradation in krill.
Lebensmittel-Wissenschaft & Technologie, May 1, 2020
Abstract Krill oil (KO) is unique in contrast to fish oil because the ω-3 PUFAs, particularly eic... more Abstract Krill oil (KO) is unique in contrast to fish oil because the ω-3 PUFAs, particularly eicosapentaenoic (EPA) and docosahexaenoic (DHA), are almost exclusively esterified on phospholipids (PL) rather than triglycerides (TAG) which improves bioavailability and water solubility. Therefore, the primary aim of this study was to use the principles of water degumming to separate PL from TAG in KO. Water was mixed with KO in varying ratios, centrifuged for separation and freeze-dried. Separation into gum and oil fractions occurred in the 75:25 and 50:50 KO:H2O samples. TLC-densitometry revealed 67.6 ± 1.97% and 49.73 ± 3.90% PL concentrations (p
Protein wasted by the disposal of fish processing by-products may be recovered using isoelectric ... more Protein wasted by the disposal of fish processing by-products may be recovered using isoelectric solubilization and precipitation. Extreme pH shifts are used to solubilize the protein and then it is recovered by precipitation and centrifugation. Microbial survival after this process is unknown; therefore, the purpose was to see if Listeria innocua would survive extreme pH shifts during the protein recovery process. Fresh rainbow trout fillets were inoculated with L. innocua, homogenized, and brought to the target pH of 2, 3, 11.5, or 12.5 by the addition of concentrated hydrochloric acid or sodium hydroxide. The proteins were allowed to solubilize at 4 degrees C for 10 min, centrifuged, and the lipid and insoluble components (bones, skin, insoluble protein, and so on) were removed. A 2nd pH shift (pH 5.5) and centrifugation was used to separate the precipitating protein and water fractions. Each constituent (lipid, protein, water, insoluble components) was analyzed for bacterial content using growth and selective media. The sums of the surviving L. innocua in these constituents were compared to the initial inoculum. There were no significant differences in recovery on growth or selective media (P > 0.05). The greatest loss occurred when the pH was shifted to 2, with a 3.1-log reduction in the combined fractions of the trout fillets and a 3.8-log reduction in the protein fraction. There were no significant losses when the pH was adjusted to 11.5 (P > 0.05). Future studies will continue to look at the effects of using organic acid, rather than inorganic, for protein solubilization.
Protein was recovered from headed gutted silver carp by isoelectric solubilization at pH 2.5, 3.0... more 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. 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.
The objective of this study was to evaluate the nutritional quality and physical characteristics ... more 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 su...
It is possible to recover muscle protein isolates from food processing by-products and under-util... more It is possible to recover muscle protein isolates from food processing by-products and under-utilized or difficult to process sources that otherwise would be discarded or diverted from direct human consumption by using isoelectric solubilization/precipitation (ISP). ISP selectively induces water solubility of muscle proteins by changing pH. When muscle proteins are dissolved, they are separated from lipids and other insoluble fractions such as skin, bones, scales, etc. Following separation, the dissolved proteins are subjected to subsequent pH change that causes protein precipitation and yields protein isolate. ISP processing efficiently recovers protein isolates of high quality from both nutritional and technological stand point. However, attempts at commercializing food products developed from the ISP-recovered protein isolates have been very limited. Results from laboratory-scale product development research demonstrate the potential for the use of ISP-recovered protein isolates as a base and functional ingredient for prototypes of nutraceutical foods with specific health benefits. This article reviews ISP as an innovative means to recover functional protein isolates from low-value sources. It also covers recent attempts to develop prototypes of nutraceutical food products using the ISP-recovered protein isolates targeting diet-driven cardiovascular disease.
The purpose of this study was to examine the influence of temperature on bacterial reduction in U... more The purpose of this study was to examine the influence of temperature on bacterial reduction in UV irradiated milk of different milk fat concentrations. Commercially processed skim, reduced fat (2%), and whole milk samples were inoculated with a naladixic acid resistant E. coli O157:H7 surrogate (ATCC 25922), maintained at or brought to 4 o C and 20 o C, respectively, and then exposed to a UV light dose between 5.3-6.3 mJ/cm 2 for approximately 1.5 sec. Bacterial populations before and after UV exposure were enumerated and the results indicated that no significant statistical differences in bacterial reductions occurred when skim milk samples were processed at 4 o C or 20 o C, as determined by Tukey's HSD test (p > 0.05). These results were the same for reduced fat milk samples processed at 4 o C and 20 o C. A significant difference was found in whole milk samples processed at the different temperatures; bacterial reductions were greater at 20 o C (p < 0.05). At 4 o C, skim milk and reduced fat milk showed a statistically significant bacterial reduction compared to whole milk (p < 0.05), whereas at 20 o C there was a significant bacterial reduction in the skim milk samples (p < 0.05) but no significant reduction in the reduced fat and whole milk samples (p > 0.05). Turbidity was measured for each milk type. Skim milk was the least turbid, followed by reduced fat and whole milk, respectively. This decrease in turbidity of skim milk samples may have contributed to the greater reduction of pathogens in the skim milk samples. Solids in the milk have a greater effect over bacterial reductions than processing temperatures.
This study aimed to evaluate the efficacy of a and hydrogen peroxide (H 2 O 2 ) and peroxyacetic-... more This study aimed to evaluate the efficacy of a and hydrogen peroxide (H 2 O 2 ) and peroxyacetic-acid (PAA) mixer delivered by conventional garden sprayer (GS), electrostatic sprayer (ES) and dip methods to inactivate Listeria monocytogenes on apples. Organic Honey Crisp ( HC ), Fuji ( FJ ), and Pink Lady ( PL ) were dip-inoculated with Listeria monocytogenes (2-strain, serotype 1/2b), which were then kept untreated (control), sprayed with water only, or treated with the H 2 O 2 -PAA mixer (0.0064, 0.1, 0.25 and 0.50%) for 20 s via GS, ES, or dip, followed by draining (2 min) on aluminum foil. Surviving bacteria were recovered on Modified Oxford agar. Atomic force microcopy was used to detect the structural changes of inactivation of L. monocytogenes in broth medium by the H 2 O 2 -PAA mixer solution. Data (2 replicates/6 samples/replicate) were analyzed using the Mixed Model Procedure of SAS ( P =0.05). Initial counts of L. monocytogenes on untreated apples were 6.80 to 6.90 log CF...
Consumer demand for fresher and minimally processed foods has brought about a movement to find ef... more Consumer demand for fresher and minimally processed foods has brought about a movement to find effective, non-thermal processing technologies for the treatment of milk. The influence of temperature on bacterial reduction in UV irradiated milk was tested. Commercially processed skim, reduced fat (2%), and whole milk samples were inoculated with a naladixic acid resistant E. coli O157:H7 surrogate (ATCC 25922), maintained at or brought to 4 o C and 20 o C, respectively, and then exposed to a UV light dose between 5.3-6.3 mJ/cm 2 for approximately 1.5 sec using the CiderSure 3500 apparatus (FPE Inc., Macedon, NY). Bacterial concentrations before and after UV exposure were enumerated and the results indicated that processing temperature was not significantly related to bacterial reduction (p > 0.05). The results did indicate that skim milk samples had a greater bacterial reduction, regardless of processing temperature compared to reduced fat milk and whole milk samples (p < 0.05). Solids such as milk fat, protein, lactose and minerals, in the milk have a greater effect over bacterial reductions than processing temperatures. Traditional goat cheeses are produced using unpasteurized milk, which increases the food safety concerns for these types of products. Fresh goat's milk was inoculated to 10 7 cfu/ml with Listeria monocytogenes (L-2289) and exposed to UV light using the CiderSure 3500 apparatus. Inoculated milk was exposed to an ultraviolet dose range between 0 and 20 mJ/cm 2 to determine the optimal UV dose. A greater than 5-log reduction was achieved (p < 0.0001) when the milk was processed 12 times for a cumulative exposure time of roughly 18 sec and a cumulative UV dose of 15.8 +/-1.6 mJ/cm 2. The results of this study indicate that UV irradiation could be used for the reduction of L. monocytogenes in goat's milk. Organoleptic consequences of goat's milk treated with UV technology were assessed. Olfactory studies were conducted and a highly significant difference was determined iii between the odor of fresh goat's milk and UV processed milk (p < 0.05). The extent of lipid oxidation and hydrolytic rancidity was measured by thiobarbituric acid reactive substances (TBARS) and acid degree values (ADVs). Results indicated that as the UV dose increased, there was a significant increase in TBARS values and ADVs of the milk samples (p < 0.05). Milk samples were processed using the UV processor under the same conditions as previously described without exposure to the UV source to determine if the agitation from pumping was causing off-flavors by way of hydrolytic rancidity. The ADVs from these samples increased at the same rate as the UV irradiated samples; however, sensory studies indicated that the increase of free fatty acids (FFA) was not enough to cause detectable offodors in the milk. Solid phase microextraction and gas chromatography (SPME-GC) was utilized to quantify the production of volatile compounds that were formed due to UV processing. The formation of pentanal, hexanal and heptanal was identified after as little as 1.3 mJ/cm 2 UV dose. Peak areas were measured and analyzed after 7.8 mJ/cm 2 and 15.6 mJ/cm 2 and were determined to increase significantly as UV dose increased (p < 0.05). The chemical analyses supported the findings from the olfactory studies. The outcome of this research showed that UV irradiation at the wavelength 254 nm, was detrimental to certain chemical properties of fluid milk. The properties that were perceived as negative in fluid milk may be considered an attribute in certain types of cheese and future studies in the cheese production sector should be considered. Other applications for this technology could be for use in developing countries where milk is not typically processed because of the high costs of thermal pasteurization. On-farm applications for the treatment of replacement milk should also be considered. iv ACKNOWLEDGEMENTS This research was made possible by funding from USDA-CSREES # 2001-51110-11363. I would like to thank Donnie Underwood of Valley Rich Dairy for organizing the donation of the commercially processed milk that was needed for parts of this research. I would also like to thank Phil Hartman of FPE, Inc. for the time and effort put into the maintenance of the CiderSure 3500. I would like to thank the faculty and staff at the Food Science and Technology Department for making my graduate program both challenging and rewarding. The support that I have received is sincerely appreciated. Specifically, I would like to thank Brian Smith for sharing his microbiological expertise and his office with me, both of which required a good sense of humor on his part. Thanks to
Marbling in meat occurs when fat is distributed throughout the skeletal muscle and is visually ap... more Marbling in meat occurs when fat is distributed throughout the skeletal muscle and is visually apparent by light streaks of fat that look like a marble pattern. It is associated with increased quality, tenderness, and likeability. Incorporating dietary conjugated linoleic acid (CLA) into finishing hog feed increases intramuscular fat and decrease backfat in harvested pigs; therefore, the purpose of this study was to determine if inclusion of CLA in pig feed would increase intramuscular marbling and consumer likeability without compromising storage stability. Twenty pigs were housed in ten pens (2 pigs per pen) and fed either 1% Soybean oil or 1% CLA diet for a period of six weeks. After slaughter, pork loins were cut and divided into cranial and caudal ends, vacuum packed and stored at -8°C until evaluations were conducted. Quality indicators of pork were measured on both raw and cooked samples over a 7-d storage period. Measurements included color (L*, a*, b*), muscle pH, texture, ...
Lebensmittel-Wissenschaft & Technologie, Dec 1, 2021
Abstract Nutritional and functional properties of protein were determined for cricket, locust, an... more Abstract Nutritional and functional properties of protein were determined for cricket, locust, and silk worm pupae powders, specifically macro-nutrient proximate composition, full amino acid composition, protein pH-solubility, and SDS-PAGE/densitometry. Cricket and locust powders contained >70 g of crude protein/100 g of sample powder (d.b. – dry basis), while silk worm pupae powder >50 g of crude protein/100 g of sample powder (d.b.). Insect powders exceeded FAO/WHO/UNU recommendations for eight of the nine essential amino acids (EAAs) for adults, but not infants. Total EAAs (21.8–23.7 g EAAs/100 g sample; d.b.) was two-times higher than FAO/WHO/UNU recommendations for adults (12.7 g EAAs/100 g sample; d.b.), but only half for infants (46.0 g/100 g; d.b.). Nearly 70% of insect protein dissolved in alkaline pH, while only 7% at pH 4–6. SDS-PAGE/densitometry showed four protein fractions: cuticle proteins, actin-arginine kinase, hemocyanin, and myosin. SDS-PAGE/densitometry also showed proteolysis and various distribution of protein fractions among insect powders. Protein may be efficiently isolated from insects using pH-solubility-precipitation; thus, resulting in isolates with high nutritional and functional quality.
Lebensmittel-Wissenschaft & Technologie, Aug 1, 2017
Mass balance analysis was conducted for isoelectric solubilization/precipitation (ISP) processing... more Mass balance analysis was conducted for isoelectric solubilization/precipitation (ISP) processing of carp, chicken, menhaden, and krill based on proximate composition of input materials and recovered fractions (i.e., protein, lipid, insoluble, and process water). Protein recovery yield and lipid reduction were also determined. Thin layer chromatography (TLC) and SDS-PAGE electrophoresis allowed determination of lipid classes and protein electrophoretic patterns. ISP concentrated crude protein (72e90 g/100 g, dry basis) and reduced total lipid (3e16 g/100 g, dry basis) in the protein fraction recovered with ISP when compared to the input materials (48e68 g of crude protein and 15e45 g of total lipid per 100 g, dry basis). Protein recovery yield and lipid reduction were 45e66 and 79e98 g/100 g, respectively. However, lipid fraction did not form when menhaden and krill were processed with ISP. Krill and menhaden lipids were distributed in the process water in addition to the protein and insoluble fractions. TLC showed that krill and menhaden lipids had high phospholipid (PL), but low triglyceride (TAG) content, contributing to emulsification and preventing formation of lipid fraction. SDS-PAGE confirmed presence of myosin and actin in protein fraction recovered from carp and chicken as well as proteolysis in menhaden and severe protein degradation in krill.
Lebensmittel-Wissenschaft & Technologie, May 1, 2020
Abstract Krill oil (KO) is unique in contrast to fish oil because the ω-3 PUFAs, particularly eic... more Abstract Krill oil (KO) is unique in contrast to fish oil because the ω-3 PUFAs, particularly eicosapentaenoic (EPA) and docosahexaenoic (DHA), are almost exclusively esterified on phospholipids (PL) rather than triglycerides (TAG) which improves bioavailability and water solubility. Therefore, the primary aim of this study was to use the principles of water degumming to separate PL from TAG in KO. Water was mixed with KO in varying ratios, centrifuged for separation and freeze-dried. Separation into gum and oil fractions occurred in the 75:25 and 50:50 KO:H2O samples. TLC-densitometry revealed 67.6 ± 1.97% and 49.73 ± 3.90% PL concentrations (p
Protein wasted by the disposal of fish processing by-products may be recovered using isoelectric ... more Protein wasted by the disposal of fish processing by-products may be recovered using isoelectric solubilization and precipitation. Extreme pH shifts are used to solubilize the protein and then it is recovered by precipitation and centrifugation. Microbial survival after this process is unknown; therefore, the purpose was to see if Listeria innocua would survive extreme pH shifts during the protein recovery process. Fresh rainbow trout fillets were inoculated with L. innocua, homogenized, and brought to the target pH of 2, 3, 11.5, or 12.5 by the addition of concentrated hydrochloric acid or sodium hydroxide. The proteins were allowed to solubilize at 4 degrees C for 10 min, centrifuged, and the lipid and insoluble components (bones, skin, insoluble protein, and so on) were removed. A 2nd pH shift (pH 5.5) and centrifugation was used to separate the precipitating protein and water fractions. Each constituent (lipid, protein, water, insoluble components) was analyzed for bacterial content using growth and selective media. The sums of the surviving L. innocua in these constituents were compared to the initial inoculum. There were no significant differences in recovery on growth or selective media (P &gt; 0.05). The greatest loss occurred when the pH was shifted to 2, with a 3.1-log reduction in the combined fractions of the trout fillets and a 3.8-log reduction in the protein fraction. There were no significant losses when the pH was adjusted to 11.5 (P &gt; 0.05). Future studies will continue to look at the effects of using organic acid, rather than inorganic, for protein solubilization.
Protein was recovered from headed gutted silver carp by isoelectric solubilization at pH 2.5, 3.0... more 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&amp;amp;amp;amp;amp;amp;amp;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&amp;amp;amp;amp;amp;amp;amp;L at removing impurities (P &amp;amp;amp;amp;amp;amp;lt; 0.05) from the recovered protein fraction and impurities were effectively removed from recovered lipids regardless of processing pH or acid type (P &amp;amp;amp;amp;amp;amp;gt; 0.05). For the most part, sodium was greater (P &amp;amp;amp;amp;amp;amp;lt; 0.05) and there was less calcium, phosphorus, magnesium, and iron (P &amp;amp;amp;amp;amp;amp;lt; 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. 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.
The objective of this study was to evaluate the nutritional quality and physical characteristics ... more 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 su...
It is possible to recover muscle protein isolates from food processing by-products and under-util... more It is possible to recover muscle protein isolates from food processing by-products and under-utilized or difficult to process sources that otherwise would be discarded or diverted from direct human consumption by using isoelectric solubilization/precipitation (ISP). ISP selectively induces water solubility of muscle proteins by changing pH. When muscle proteins are dissolved, they are separated from lipids and other insoluble fractions such as skin, bones, scales, etc. Following separation, the dissolved proteins are subjected to subsequent pH change that causes protein precipitation and yields protein isolate. ISP processing efficiently recovers protein isolates of high quality from both nutritional and technological stand point. However, attempts at commercializing food products developed from the ISP-recovered protein isolates have been very limited. Results from laboratory-scale product development research demonstrate the potential for the use of ISP-recovered protein isolates as a base and functional ingredient for prototypes of nutraceutical foods with specific health benefits. This article reviews ISP as an innovative means to recover functional protein isolates from low-value sources. It also covers recent attempts to develop prototypes of nutraceutical food products using the ISP-recovered protein isolates targeting diet-driven cardiovascular disease.
The purpose of this study was to examine the influence of temperature on bacterial reduction in U... more The purpose of this study was to examine the influence of temperature on bacterial reduction in UV irradiated milk of different milk fat concentrations. Commercially processed skim, reduced fat (2%), and whole milk samples were inoculated with a naladixic acid resistant E. coli O157:H7 surrogate (ATCC 25922), maintained at or brought to 4 o C and 20 o C, respectively, and then exposed to a UV light dose between 5.3-6.3 mJ/cm 2 for approximately 1.5 sec. Bacterial populations before and after UV exposure were enumerated and the results indicated that no significant statistical differences in bacterial reductions occurred when skim milk samples were processed at 4 o C or 20 o C, as determined by Tukey's HSD test (p > 0.05). These results were the same for reduced fat milk samples processed at 4 o C and 20 o C. A significant difference was found in whole milk samples processed at the different temperatures; bacterial reductions were greater at 20 o C (p < 0.05). At 4 o C, skim milk and reduced fat milk showed a statistically significant bacterial reduction compared to whole milk (p < 0.05), whereas at 20 o C there was a significant bacterial reduction in the skim milk samples (p < 0.05) but no significant reduction in the reduced fat and whole milk samples (p > 0.05). Turbidity was measured for each milk type. Skim milk was the least turbid, followed by reduced fat and whole milk, respectively. This decrease in turbidity of skim milk samples may have contributed to the greater reduction of pathogens in the skim milk samples. Solids in the milk have a greater effect over bacterial reductions than processing temperatures.
This study aimed to evaluate the efficacy of a and hydrogen peroxide (H 2 O 2 ) and peroxyacetic-... more This study aimed to evaluate the efficacy of a and hydrogen peroxide (H 2 O 2 ) and peroxyacetic-acid (PAA) mixer delivered by conventional garden sprayer (GS), electrostatic sprayer (ES) and dip methods to inactivate Listeria monocytogenes on apples. Organic Honey Crisp ( HC ), Fuji ( FJ ), and Pink Lady ( PL ) were dip-inoculated with Listeria monocytogenes (2-strain, serotype 1/2b), which were then kept untreated (control), sprayed with water only, or treated with the H 2 O 2 -PAA mixer (0.0064, 0.1, 0.25 and 0.50%) for 20 s via GS, ES, or dip, followed by draining (2 min) on aluminum foil. Surviving bacteria were recovered on Modified Oxford agar. Atomic force microcopy was used to detect the structural changes of inactivation of L. monocytogenes in broth medium by the H 2 O 2 -PAA mixer solution. Data (2 replicates/6 samples/replicate) were analyzed using the Mixed Model Procedure of SAS ( P =0.05). Initial counts of L. monocytogenes on untreated apples were 6.80 to 6.90 log CF...
Consumer demand for fresher and minimally processed foods has brought about a movement to find ef... more Consumer demand for fresher and minimally processed foods has brought about a movement to find effective, non-thermal processing technologies for the treatment of milk. The influence of temperature on bacterial reduction in UV irradiated milk was tested. Commercially processed skim, reduced fat (2%), and whole milk samples were inoculated with a naladixic acid resistant E. coli O157:H7 surrogate (ATCC 25922), maintained at or brought to 4 o C and 20 o C, respectively, and then exposed to a UV light dose between 5.3-6.3 mJ/cm 2 for approximately 1.5 sec using the CiderSure 3500 apparatus (FPE Inc., Macedon, NY). Bacterial concentrations before and after UV exposure were enumerated and the results indicated that processing temperature was not significantly related to bacterial reduction (p > 0.05). The results did indicate that skim milk samples had a greater bacterial reduction, regardless of processing temperature compared to reduced fat milk and whole milk samples (p < 0.05). Solids such as milk fat, protein, lactose and minerals, in the milk have a greater effect over bacterial reductions than processing temperatures. Traditional goat cheeses are produced using unpasteurized milk, which increases the food safety concerns for these types of products. Fresh goat's milk was inoculated to 10 7 cfu/ml with Listeria monocytogenes (L-2289) and exposed to UV light using the CiderSure 3500 apparatus. Inoculated milk was exposed to an ultraviolet dose range between 0 and 20 mJ/cm 2 to determine the optimal UV dose. A greater than 5-log reduction was achieved (p < 0.0001) when the milk was processed 12 times for a cumulative exposure time of roughly 18 sec and a cumulative UV dose of 15.8 +/-1.6 mJ/cm 2. The results of this study indicate that UV irradiation could be used for the reduction of L. monocytogenes in goat's milk. Organoleptic consequences of goat's milk treated with UV technology were assessed. Olfactory studies were conducted and a highly significant difference was determined iii between the odor of fresh goat's milk and UV processed milk (p < 0.05). The extent of lipid oxidation and hydrolytic rancidity was measured by thiobarbituric acid reactive substances (TBARS) and acid degree values (ADVs). Results indicated that as the UV dose increased, there was a significant increase in TBARS values and ADVs of the milk samples (p < 0.05). Milk samples were processed using the UV processor under the same conditions as previously described without exposure to the UV source to determine if the agitation from pumping was causing off-flavors by way of hydrolytic rancidity. The ADVs from these samples increased at the same rate as the UV irradiated samples; however, sensory studies indicated that the increase of free fatty acids (FFA) was not enough to cause detectable offodors in the milk. Solid phase microextraction and gas chromatography (SPME-GC) was utilized to quantify the production of volatile compounds that were formed due to UV processing. The formation of pentanal, hexanal and heptanal was identified after as little as 1.3 mJ/cm 2 UV dose. Peak areas were measured and analyzed after 7.8 mJ/cm 2 and 15.6 mJ/cm 2 and were determined to increase significantly as UV dose increased (p < 0.05). The chemical analyses supported the findings from the olfactory studies. The outcome of this research showed that UV irradiation at the wavelength 254 nm, was detrimental to certain chemical properties of fluid milk. The properties that were perceived as negative in fluid milk may be considered an attribute in certain types of cheese and future studies in the cheese production sector should be considered. Other applications for this technology could be for use in developing countries where milk is not typically processed because of the high costs of thermal pasteurization. On-farm applications for the treatment of replacement milk should also be considered. iv ACKNOWLEDGEMENTS This research was made possible by funding from USDA-CSREES # 2001-51110-11363. I would like to thank Donnie Underwood of Valley Rich Dairy for organizing the donation of the commercially processed milk that was needed for parts of this research. I would also like to thank Phil Hartman of FPE, Inc. for the time and effort put into the maintenance of the CiderSure 3500. I would like to thank the faculty and staff at the Food Science and Technology Department for making my graduate program both challenging and rewarding. The support that I have received is sincerely appreciated. Specifically, I would like to thank Brian Smith for sharing his microbiological expertise and his office with me, both of which required a good sense of humor on his part. Thanks to
Marbling in meat occurs when fat is distributed throughout the skeletal muscle and is visually ap... more Marbling in meat occurs when fat is distributed throughout the skeletal muscle and is visually apparent by light streaks of fat that look like a marble pattern. It is associated with increased quality, tenderness, and likeability. Incorporating dietary conjugated linoleic acid (CLA) into finishing hog feed increases intramuscular fat and decrease backfat in harvested pigs; therefore, the purpose of this study was to determine if inclusion of CLA in pig feed would increase intramuscular marbling and consumer likeability without compromising storage stability. Twenty pigs were housed in ten pens (2 pigs per pen) and fed either 1% Soybean oil or 1% CLA diet for a period of six weeks. After slaughter, pork loins were cut and divided into cranial and caudal ends, vacuum packed and stored at -8°C until evaluations were conducted. Quality indicators of pork were measured on both raw and cooked samples over a 7-d storage period. Measurements included color (L*, a*, b*), muscle pH, texture, ...
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