Biomedical subjects

W J Harper

Publications and source records attributed to W J Harper.

At least 19 recordsLinked to original sources

PubMed2006

Rapid determination of Swiss cheese composition by Fourier transform infrared/attenuated total reflectance spectroscopy.

There is a need for rapid and simple techniques that can be used to predict the quality of cheese. The aim of this research was to develop a simple and rapid screening tool for monitoring Swiss cheese composition by using Fourier transform infrared spectroscopy. Twenty Swiss cheese samples from different manufacturers and degree of maturity were evaluated. Direct measurements of Swiss cheese slices (approximately 0.5 g) were made using a MIRacle 3-reflection diamond attenuated total reflectance (ATR) accessory. Reference methods for moisture (vacuum oven), protein content (Kjeldahl), and fat (Babcock) were used. Calibration models were developed based on a cross-validated (leave-one-out approach) partial least squares regression. The information-rich infrared spectral range for Swiss cheese samples was from 3,000 to 2,800 cm(-1) and 1,800 to 900 cm(-1). The performance statistics for cross-validated models gave estimates for standard error of cross-validation of 0.45, 0.25, and 0.21% for moisture, protein, and fat respectively, and correlation coefficients r > 0.96. Furthermore, the ATR infrared protocol allowed for the classification of cheeses according to manufacturer and aging based on unique spectral information, especially of carbonyl groups, probably due to their distinctive lipid composition. Attenuated total reflectance infrared spectroscopy allowed for the rapid (approximately 3-min analysis time) and accurate analysis of the composition of Swiss cheese. This technique could contribute to the development of simple and rapid protocols for monitoring complex biochemical changes, and predicting the final quality of the cheese.

Analysis of Variance↗

PubMed2004

Influence of starter culture ratios and warm room treatment on free fatty acid and amino acid in Swiss cheese.

Quantification of water-soluble volatile free fatty acids (FFA) and free amino acids (FAA) was performed as a ripening index and an indirect measure of flavor development in Swiss-type cheeses. The objective of this research was to assess the effect of warm room treatment (WRT) and usage ratio of starter cultures, Streptococcus thermophilus and Lactobacillus helveticus vs. propionibacteria, on the concentration of FFA and FAA in pilot plant-scale Swiss cheese. A capillary gas chromatograph equipped with a flame ionization detector was used for the analysis of FFA in Swiss cheese. Free amino acids were analyzed by the Cd-ninhydrin method. Starter culture ratios did not affect development of FAA during the cheese ripening. However, duration of WRT had an effect on the concentration of FAA in the Swiss cheese. Free amino acids increased considerably during WRT. A continuous increase in FAA was shown during 70-d ripening time after WRT. The concentrations of C2:0 and C3:0 fatty acids were affected by starter culture ratios after 2-wk WRT, but these differences had mostly disappeared after 3-wk WRT. Similar concentrations of FFA and FAA reported in previous studies were developed in Swiss cheese with a 3-wk WRT and a 0.33:1 ratio of Streptococcus thermophilus and Lactobacillus helveticus to propionibacteria.

Amino Acids↗

PubMed2003

Effect of whey protein isolate on intracellular glutathione and oxidant-induced cell death in human prostate epithelial cells.

Cysteine is the rate-limiting amino acid for synthesis of the ubiquitous antioxidant glutathione (GSH). Bovine whey proteins are rich in cystine, the disulfide form of the amino acid cysteine. The objective of this study was to determine whether enzymatically hydrolyzed whey protein isolate (WPI) could increase intracellular GSH concentrations and protect against oxidant-induced cell death in a human prostate epithelial cell line (designated RWPE-1). Treatment of RWPE-1 cells with hydrolyzed WPI (500 microg/ml) significantly increased intracellular GSH by 64%, compared with control cells receiving no hydrolyzed WPI (P<0.05). A similar increase in GSH was observed with N-acetylcysteine (500 microM), a cysteine-donating compound known to elevate intracellular GSH. In contrast, treatment with hydrolyzed sodium caseinate (500 microg/ml), a cystine-poor protein source, did not significantly elevate intracellular GSH. Hydrolyzed WPI (500 microg/ml) significantly protected RWPE-1 cells from oxidant-induced cell death, compared with controls receiving no WPI (P<0.05). The results of this study indicate that WPI can increase GSH synthesis and protect against oxidant-induced cell death in human prostate cells.

Antioxidants↗

PubMed2002

Maillard reaction induced lactose attachment to bovine beta-lactoglobulin: electrospray ionization and matrix-assisted laser desorption/ionization examination.

Nonenzymatic attachment of lactose to beta-lactoglobulin (beta-Lg) was investigated under different conditions. Solubilized conditions, dry environment, and a combination of dry and solubilized environments, were examined for their effects on lactosylation. Temperatures ranging from 50 to 65 degrees C and time intervals between 1 h and 4 days were used. Electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry were implemented to examine the reaction products. Maximum attachment efficiency occurred at 65 degrees C held for 3 h in dry-way conditions. Incubations held for long periods of time under dry-way conditions suggest possible denaturation. Both ESI and MALDI data suggest beta-Lg removal in the solubilized samples held for long periods of time. A combination of solubilized and dry environments led to very similar mass spectrogram results over time.

Animals↗

PubMed2002

Genetic diversity in Swiss cheese starter cultures assessed by pulsed field gel electrophoresis and arbitrarily primed PCR.

AIMS: To assess intraspecific genetic heterogeneity among commercial Swiss cheese starter culture strains of Lactobacillus helveticus, Streptococcus thermophilus and Propionibacterium freudenreichii and to compare the efficacy of two genetic typing methods. METHODS AND RESULTS: Two genetic typing methods, pulsed field gel electrophoresis (PFGE) and arbitrarily primed PCR (AP-PCR), were used. Nine Strep. thermophilus strains revealed eight PFGE and five AP-PCR genotypes. Seventeen Lactobacillus strains yielded 16 and five genotypes by PFGE and AP-PCR, respectively. Eleven Propionibacterium strains yielded 10 PFGE genotypes. Cluster analysis of PFGE profiles generated similarity coefficients for Strep. thermophilus, Lact. helveticus and Prop. freudenreichii strains of 29.5%, 60.3%, and 30.5%, respectively. Milk acidification rates for Strep. thermophilus and Lact. helveticus were determined. CONCLUSIONS: Pulsed field gel electrophoresis is more discriminatory than AP-PCR. The Lact. helveticus group is more homogeneous than the other species examined. Strains with > 87% similarity by PFGE consistently had the same acidification rate and AP-PCR profile. SIGNIFICANCE AND IMPACT OF THE STUDY: Bacterial strains sold for Swiss cheese manufacture in the United States are genetically diverse. Clustering of genetically related bacteria may be useful in identifying new strains with industrially relevant traits.

Bacterial Typing Techniques↗

PubMed2002

The impact of wood ice cream sticks' origin on the aroma of exposed ice cream mixes.

The effect of volatile compounds in white birch sticks obtained from four different geographical locations on the aroma of ice cream mix was investigated. Sensory evaluation, (specifically, a series of warmed-up paired comparisons) was conducted on stick-exposed ice cream mixes to determine whether aroma differences in those mixes could be detected. Batches of ice cream mix were exposed to the sticks and aged for 6 d at 4 degrees C and then assessed by the panelists by pairwise comparison. Findings suggest that differences in aroma of mixes that have been exposed to white birch sticks from four different geographical origins can be distinguished perceptually.

Food Technology↗

PubMed2001

The strengths and weaknesses of the electronic nose.

Arrays of electronic sensors, capable of detecting and differentiating complex mixtures of volatile compounds, have been utilized to differentiate aromas of food and related materials. These sensor arrays have been dubbed "Electronic Noses" and have been commercially available in the USA for the past 4-5 years. Electronic nose technology is still in its development phase, both in respect to hardware and software development. The instruments contain an array of from one to 32 sensors, using a variety of different sensor technologies--from organic polymers to metal oxides to micro-balances. Electronic noses are being widely used by some companies as a quality control instrument. Strengths include high sensitivity and correlation to human sensory panels for many applications. Limitations to their full potential includes loss of sensitivity in the presence of water vapor or high concentrations of a single component like alcohol; sensor drift and the inability to provide absolute calibration: relatively short life of some sensors; necessity to do considerable method development work for each specific application; and lack of being able to obtain quantitative data for aroma differences. They do have a high sensitivity (ppt to ppm) and are often more sensitive than the human nose. There is some evidence that sensors differentiate aromas on the basis of relatively few compounds and in the future a relationship between specific chemicals and a single flavor attribute may be achievable. Also, the possibility exists to differentiate between "top" and "middle" notes of aroma.

Biosensing Techniques↗

PubMed2001

Relationships among dietary roasted soybeans, milk components, and spontaneous oxidized flavor of milk.

Relationships among dietary roasted whole soybeans (RSB), milk fatty acid profile, and the development of spontaneous oxidized flavor of milk were investigated by using 20 commercial dairy herds. Diets contained 0 to 15.3% of dry matter as RSB. Concentrations of dietary RSB were correlated positively with concentrations of C18:2 and C18:3 in milk fat. Concentrations of alpha-tocopherol, beta-carotene, and ascorbic acid in milk decreased from 0 to 3 d of storage (4 degrees C), and oxidized flavor in milk increased linearly between 0 and 8 d of storage. Milk fatty acid profile did not change during storage. The development of oxidized flavor at 8 d postsampling was correlated (r) with increased concentrations in milk fat of C18:2 (0.49), C18:3 (0.55), total polyunsaturated milk fatty acids (0.50), and dietary concentrations of RSB (0.38). Multiple regression was used to quantify relationships between variables and oxidized flavor (samples stored 8 d). All significant models included milk concentrations of Cu and dehydroascorbic acid. Concentrations of C18:2, C18:3, or total polyunsaturated fatty acids in milk fat, or dietary RSB concentrations, and interactions of those variables with Cu were included in individual models. Milk with high concentrations of polyunsaturated fatty acids and Cu were most susceptible to oxidation. Feeding RSB increased polyunsaturated fatty acid concentrations in milk fat, which increased the likelihood of oxidized flavor, especially when milk had high concentrations of Cu.

Animal Feed↗

PubMed1999

Maximizing the value of milk through separation technologies.

Milk is the source of a wide range of proteins that deliver nutrition to the most promising new food products today. Isolated milk proteins are natural, trusted food ingredients with excellent functionality. Separation technologies provide the basis for adding value to milk through the production of proteins that provide the food industry with ingredients to meet specific needs, not possible with milk itself or with other ingredients. The major milk proteins, casein and whey protein, can be isolated by manipulating their compositional and physical properties and then by using various separation technologies to recover the proteins. Additionally, they can be processed in various ways to create a wide range of ingredients with diverse functional characteristics. These ingredients include milk protein concentrate, milk protein isolate, casein, caseinate, whey protein concentrate, whey protein isolate, hydrolysates, and various milk fractions. Within each of these ingredient categories, there is further differentiation according to the functional and nutritional requirements of the finished food. Adding value to milk by expanding from consumer products to ingredients often requires different technologies, marketing structure and distribution channels. The worldwide market for both consumer products and ingredients from milk continues to grow. Technology often precedes market demand. Methods for the commercial production of individual milk components now exist, and in the future as clinical evidence develops, the opportunity for adding value to dairy products as functional foods with health benefits may be achieved. The research and development of today will be the basis of those value-added milk products for tomorrow.

Animals↗

PubMed1988

Surgical complications of the Garren-Edwards Gastric Bubble.

A retrospective review of our initial experience with the Garren-Edwards Gastric Bubble (American Edwards Laboratories) was undertaken to study its surgical complications. Between 22 February and 30 August 1986, 250 patients had 275 gastric bubbles endoscopically inserted as an adjuvant treatment for morbid obesity. Profiles of the first 104 patients revealed a mean weight of 113.0 kilograms (74 per cent above ideal body weight) and a mean weight loss of 10.1 kilograms (0.76 kilogram per week) followed by a gain of 0.48 kilogram from the period of peak weight loss at 13.7 weeks to removal at 19.4 weeks. Thirty-three per cent had endoscopic removal and the remainder passed per rectum. Ninety-two had undergone previous abdominal operation. Five instances of obstruction of the upper part of the gastrointestinal tract (mean 18.3 weeks after insertion) required three operative removals, one endoscopic retrieval from the second portion of the duodenum and one hypaque small intestinal series with oral mineral oil to induce spontaneous passage. Four of the five patients had prior abdominal operations--cholecystectomy in one instance, appendectomy in one, cholecystectomy and appendectomy in one and exploratory laparotomy for multiple stab wounds in one. One (multiple stab wounds) had adhesions at the point of the obstruction. The patient who underwent endoscopic retrieval had premature deflation at 6.7 weeks presumably due to a defective bubble. The weight gain after peak weight loss at 13.7 weeks likely represents spontaneous bubble deflation. Prior abdominal surgical treatment appears to be a significant risk factor for the development of obstruction after bubble deflation. In addition, two of five patients have been lost to follow-up study after insertion. Proper patient selection and careful monitoring may be crucial in reducing the morbidity associated with the Garren-Edwards Gastric Bubble.

Abdomen↗

PubMed1984

Effect of cheese, with and without sucrose, on dental caries and recovery of Streptococcus mutans in rats.

The objective of this study was to determine the effect of aged and young cheddar cheese with and without added sucrose on dental caries and the associated recovery of implanted Streptococcus mutans. Very little caries was observed in rats consuming cheese without sucrose. There was an increase in caries in rats fed cheeses with 20% sucrose, but this increase was not significant. There was significantly greater caries activity in rats fed standard diets containing 20% or 5% sucrose (SLS or MIT 305) than in rats fed cheeses containing 20% sucrose. Rats fed cheese or powdered diets containing sucrose had significantly higher frequency of recovery and higher levels of S. mutans infection than did rats fed cheese containing no sucrose. This study confirms the low cariogenic potential and possible cariostatic activity of cheddar cheese in rats. Since cheddar cheese with sucrose did not significantly interfere with S. mutans implantation, the cariostatic mechanism is apparently unrelated to a direct antimicrobial effect on S. mutans.

Animals↗

PubMed1976

Polyunsaturated meat and dairy products in fat-modified food patterns for hyperlipidemia.

Polyunsaturated meat and dairy products were compared with their saturated counterparts to determine their usefulness in a fat-modified diet for hyperlipidemic persons and their spouses. These polyunsaturated animal products were produced by feeding cattle a supplement of oil droplets coated with denatured protein. As a result, the polyunsaturated fatty acid content was 27 to 28 per cent of the meat fat and butterfat; saturated fatty acids (C12:0 to tc16:0) were 18 to 19 per cent. Of the eleven free-living subjects three were normocholesteremic, three had type IIa hyperlipidemia and five had type VI (IIb). In the fourteen-week study, an adjustment period of three weeks was followed by two consecutive experimental periods of four weeks each, then by a three-week follow-up period. During the adjustment period, participants continued to follow their usual eating patterns. During both experimental periods all followed the same prescribed fat modified food pattern using polyunsaturated margarine and oil. Five participants ate polyunsaturated beef and dairy products during the first experimental period and their saturated counterparts in the second; six participants ate saturated products first, then polyunsaturated. During the follow-up period, all participants selected all their own food. Serum cholesterol levels in five participants who had not previously followed a fat-modified diet were reduced by 18 per cent with polyunsaturated animal products and 11 per cent with saturated products. Serum cholesterol in six participants, previously on a fat-modified diet, was not significantly changed with polyunsaturated products. In ten of eleven participants, serum cholesterol levels were an average of 6 per cent lower with polyunsaturated products than with saturated products. It is concluded that polyunsaturated animal products are suitable for use in fat-modified food patterns for reducing hyperlipidemia, with some restrictions in the amount of polyunsaturated animal fat and with the inclusion of polyunsaturated oil and margarine.

Adult↗

PubMed1968