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Biomedical subjects

S E Duncan

Publications and source records attributed to S E Duncan.

12 recordsLinked to original sources
PubMed2003

Oxidation and textural characteristics of butter and ice cream with modified fatty acid profiles.

The primary objective of this study was to evaluate oxidation and firmness of butter and ice cream made with modified milkfat containing enhanced amounts of linoleic acid or oleic acid. The influence of the fatty acid profile of the HO milkfat relating to product properties as compared with the influence the fatty acid profile of the HL milkfat was the main focus of the research. Altering the degree of unsaturation in milkfat may affect melting characteristics and oxidation rates, leading to quality issues in dairy products. Three milkfat compositions (high-oleic, high-linoleic, and control) were obtained by modifying the diets of Holstein cows. Ice cream and butter were processed from milkfat obtained from cows in each dietary group. Butter and ice cream samples were analyzed to determine fatty acid profile and firmness. High-oleic milkfat resulted in a softer butter. Solid fat index of high-oleic and high-linoleic milkfat was lower than the control. Control ice cream mix had higher viscosity compared with high-oleic and high-linoleic, but firmness of all ice creams was similar when measured between -17 and -13 degrees C. Nutritional and textural properties of butter and ice cream can be improved by modifying the diets of cows.

Animal Feed↗
PubMed2001

Flavor threshold for acetaldehyde in milk, chocolate milk, and spring water using solid phase microextraction gas chromatography for quantification.

The detection threshold of acetaldehyde was determined on whole, lowfat, and nonfat milks, chocolate-flavored milk, and spring water. Knowledge of the acetaldehyde threshold is important because acetaldehyde forms in milk during storage as a result of light oxidation. It is also a degradation product of poly(ethylene terephthalate) during melt processing, a relatively new packaging choice for milk and water. There was no significant difference in the acetaldehyde threshold in milk of various fat contents, with thresholds ranging from 3939 to 4040 ppb. Chocolate-flavored milk and spring water showed thresholds of 10048 and 167 ppb, respectively, which compares favorably with previous studies. Solid phase microextraction (SPME) was verified as an effective method for the recovery of acetaldehyde in all media with detection levels as low as 200 and 20 ppb in milk and water, respectively, when using a polydimethyl siloxane/Carboxen SPME fiber in static headspace at 45 degrees C for 15 min.

Acetaldehyde↗
PubMed2001

Effectiveness of poly(ethylene terephthalate) and high-density polyethylene in protection of milk flavor.

The development of certain off-flavors in whole milk (3.25% milk fat) as related to packaging material [glass, high-density polyethylene (HDPE), amber poly(ethylene terephthalate) (PETE), clear PETE, and clear PETE-UV] were evaluated after exposure to fluorescent light (1100 to 1300 lx) for 18 d at 4 degrees C. Control samples packaged and stored under identical conditions were wrapped in foil to prevent light exposure. Selected flavor compounds in milk were measured analytically on d 0, 7, 14, and 18 of storage, while intensities of "oxidation," "acetaldehyde," and "lacks freshness" off-flavors were determined by sensory analysis at the same intervals. In light-exposed samples, oxidation off-flavor was significantly lower when packaged in amber PETE versus other containers. Milk packaged in HDPE containers showed a significantly higher level of oxidation off-flavor than milk packaged in PETE-UV containers but not higher than clear PETE or glass containers. No significant difference in acetaldehyde off-flavor was found between package material treatments (exposed or protected). Acetaldehyde concentration never exceeded flavor threshold levels, regardless of packaging material. Amber and PETE-UV materials proved to be a competitive packaging choice for milk in preserving fresh milk flavor.

Animals↗
PubMed2000

Quality and sensory characteristics of selected post-rigor, early deboned broiler breast meat tenderized using hydrodynamic shock waves.

Our first objective was to determine the effects of explosive amount and distance of the explosive to the meat surface in the Hydrodyne process on broiler breast tenderness. Early deboned (EB) breasts were removed immediately after initial chill (45 min postmortem), stored for 24 h (4 C), and subjected to one of four Hydrodyne treatments (200 g at 20 cm, 350 g at 23 cm, 275 g at 20 cm, or 350 g at 20 cm). Breasts were water-cooked (78 C internal). Hydrodyne treatment (HYD) of 350 g at 20 cm produced the greatest reduction (28.3%) in Warner-Bratzler shear (WBS, 1.9-cm wide strips). This combination was the only treatment to improve tenderness (peak force 4.3 kg) to a level equivalent (P > 0.05) to aged controls (CA; peak force 3.1 kg). The second objective was to determine the quality and sensory characteristics of Hydrodyne-treated (350 g explosive at 20 cm) broiler breasts as compared with CA and EB. The WBS values (1.0-cm wide and thick strips) for CA (1.56 kg) were different from both HYD (3.7 kg) and EB breasts (4.7 kg). The CA resulted in more tender, flavorful, and juicer breasts than EB and HYD. The EB was higher in initial moisture release than HYD. The EB breasts with tenderness problems can be tenderized by the Hydrodyne process based on WBS results. However, higher levels of explosive may be required to optimize the tenderness improvement of EB breasts that vary significantly in initial tenderness.

Animals↗
PubMed2000

Focus groups identified women's perceptions of dairy foods.

Focus groups were conducted with 39 Caucasian women (ages 30-55 years) to gain insight regarding their thoughts and feelings toward dairy foods. Women resided in Virginia; all had at least a high school education. Themes characterizing the group discussions were identified. Women knew that dairy foods were a good source of calcium and discussed it in relation to osteoporosis. Although many knew the risk factors related to osteoporosis, most were confused about measures to prevent it. Many used calcium supplements or vitamin/mineral supplements to help meet calcium requirements. Most thought dairy foods were high in fat. Women also discussed the sensory attributes of dairy foods as well as convenience and cost of dairy foods in relation to their dairy food choices.

Adult↗
PubMed2000

Probiotic culture survival and implications in fermented frozen yogurt characteristics.

Low-fat ice cream mix was fermented with probiotic-supplemented and traditional starter culture systems and evaluated for culture survival, composition, and sensory characteristics of frozen product. Fermentations were stopped when the titratable acidity reached 0.15% greater than the initial titratable acidity (end point 1) or when the pH reached 5.6 (end point 2). Mix was frozen and stored for 11 wk at -20 degrees C. The traditional yogurt culture system contained the strains Streptococcus salivarius ssp. thermophilus and Lactobacillus delbrueckii ssp. bulgaricus. The probiotic-supplemented system contained the traditional cultures as well as Bifidobacterium longum and Lactobacillus acidophilus. We compared recovery of Bifodobacterium by three methods, a repair-detection system with roll-tubes and plates on modified bifid glucose medium and plates with maltose + galactose reinforced clostridial medium. Culture bacteria in both systems did not decrease in the yogurt during frozen storage. The roll-tube method with modified bifid glucose agar and repair detection system provided at least one-half log10 cfu/ml higher recovery of B. longum compared with recoveries using modified bifid glucose agar or maltose + galactose reinforced clostridial agar on petri plates. No change in concentrations of lactose or protein for products fermented with either culture system occurred during storage. Acid flavor was more intense when product was fermented to pH 5.6, but yogurt flavor was not intensified. The presence of probiotic bacteria in the supplemented system seemed to cause no differences in protein and lactose concentration and sensory characteristics.

Bifidobacterium↗
PubMed1994

Extraction and detection of sulfamethazine in spray-dried milk.

Processes that reduce moisture content of fluid milk may result in a high concentration of animal drug residues that are undetectable in the fluid milk on the basis of the same weights. The objectives were to determine the amount of sulfamethazine in spray-dried milk powder manufactured from fluid milk contaminated with sulfamethazine and to determine the effectiveness of supercritical fluid extraction as a means to extract sulfamethazine from dry milk powder. Fluid whole (3.25% fat) and skim milks with sulfamethazine added at concentrations of 5, 10, and 100 ppb were spray-dried. Based on total solids, observed concentrations were 493 and 523 ppb in skim and whole dry milk powders, respectively, compared with fluid milk containing 100 ppb of sulfamethazine as determined by HPLC. The increase in sulfamethazine concentration from fluid to dry milk was also measured quantitatively by a microbial receptor assay and an ELISA. Poor recoveries and variability in data were possibly due to binding of sulfamethazine to undetermined milk components. Dry milk powder with measured concentrations of sulfamethazine was treated with supercritical CO2. Sulfamethazine was not detectable in the extracted dry milk powder by microbial receptor assay or ELISA.

Animals↗
PubMed1983

Age and weight as determinants of warfarin requirements.

A survey of patients attending anticoagulant clinics at a District General Hospital showed the maintenance dose of warfarin to increase with weight and decrease with age. A significant correlation was observed between age and weight considered together and the maintenance dose. It is proposed that consideration of age and weight may be of value when prescribing loading or starting doses of warfarin at initiation of therapy.

Age Factors↗
PubMed1974

A clinical experience with intraoperative autotransfusion.

Utilizing a disposable unit, intraoperative autotranfusion was employed during surgery in 53 patients admitted to the Bexar County Teaching Hospital at the University of Texas Health Science Center at San Antonio. During the two-year period of study, 26 patients underwent surgery for major traumatic injuries, 8 for ruptured ectopic pregnancy and 19 for miscellaneous emergency or elective conditions. The indication for intraoperative autotransfusion was an anticipated blood loss of 1,000 ml or more. Contraindications for its use were colon injury or localized infection. Over 325 units of blood were salvaged and returned directly to these patients during surgery. One death related to the use of the autotransfusor unit was due to massive air embolism. Twenty other deaths were associated with severe injuries and irreversible shock requiring greater than 3,600 ml of both autologous and homologous blood. Eight of these patients demonstrated severe pancoagulopathies. In the remaining patients, clotting factors and plasma or urine hemoglobin levels were transiently abnormal. However, there were no clinically apparent bleeding defects or renal problems detected. Postoperative blood cultures were consistently negative. It is concluded that intraoperative autotransfusion, when properly employed, is a safe, practical and technically feasible procedure.

Abdominal Injuries↗