Effects of locust bean gum and mono- and diglyceride concentrations on particle size and melting rates of ice cream.

The objective of this study was to determine how varying concentrations of the stabilizer, locust bean gum (LBG), and different levels of the emulsifier, mono- and diglycerides (MDGs), influenced fat aggregation and melting characteristics of ice cream. Ice creams were made containing MDGs and LBG singly and in combination at concentrations ranging between 0.0% to 0.14% and 0.0% to 0.23%, respectively. Particle size analysis, conducted on both the mixes and ice cream, and melting rate testing on the ice cream were used to determine fat aggregation. No significant differences (P < 0.05) were found between particle size values for experimental ice cream mixes. However, higher concentrations of both LBG and MDG in the ice creams resulted in values that were larger than the control. This study also found an increase in the particle size values when MDG levels were held constant and LBG amounts were increased in the ice cream. Ice creams with higher concentrations of MDG and LBG together had the greatest difference in the rate of melting than the control. The melting rate decreased with increasing LBG concentrations at constant MDG levels. These results illustrated that fat aggregation may not only be affected by emulsifiers, but that stabilizers may play a role in contributing to the destabilization of fat globules.

High-pressure effects on the microstructure, texture, and color of white-brined cheese.

UNLABELLED: White-brined cheeses were subjected to high-pressure processing (HPP) at 50, 100, 200, and 400 MPa at 22 °C for 5 and 15 min and ripened in brine for 60 d. The effects of pressure treatment on the chemical, textural, microstructural, and color were determined. HPP did not affect moisture, protein, and fat contents of cheeses. Similar microstructures were obtained for unpressurized cheese and pressurized cheeses at 50 and 100 MPa, whereas a denser and continuous structure was obtained for pressurized cheeses at 200 and 400 MPa. These microstructural changes exhibited a good correlation with textural changes. The 200 and 400 MPa treatments resulted in significantly softer, less springy, less gummy, and less chewy cheese. Finally, marked differences were obtained in a* and b* values at higher pressure levels for longer pressure-holding time and were also supported by ΔE* values. The cheese became more greenish and yellowish with the increase in pressure level. PRACTICAL APPLICATION: The quality of cheese is the very important to the consumers. This study documented the pressure-induced changes in selected quality attributes of semisoft and brine-salted cheese. The results can help the food processors to have knowledge of the process parameters resulting in quality changes and to identify optimal process parameters for preserving pressure-treated cheeses.

Rapid profiling of Swiss cheese by attenuated total reflectance (ATR) infrared spectroscopy and descriptive sensory analysis.

The acceptability of cheese depends largely on the flavor formed during ripening. The flavor profiles of cheeses are complex and region- or manufacturer-specific which have made it challenging to understand the chemistry of flavor development and its correlation with sensory properties. Infrared spectroscopy is an attractive technology for the rapid, sensitive, and high-throughput analysis of foods, providing information related to its composition and conformation of food components from the spectra. Our objectives were to establish infrared spectral profiles to discriminate Swiss cheeses produced by different manufacturers in the United States and to develop predictive models for determination of sensory attributes based on infrared spectra. Fifteen samples from 3 Swiss cheese manufacturers were received and analyzed using attenuated total reflectance infrared spectroscopy (ATR-IR). The spectra were analyzed using soft independent modeling of class analogy (SIMCA) to build a classification model. The cheeses were profiled by a trained sensory panel using descriptive sensory analysis. The relationship between the descriptive sensory scores and ATR-IR spectra was assessed using partial least square regression (PLSR) analysis. SIMCA discriminated the Swiss cheeses based on manufacturer and production region. PLSR analysis generated prediction models with correlation coefficients of validation (rVal) between 0.69 and 0.96 with standard error of cross-validation (SECV) ranging from 0.04 to 0.29. Implementation of rapid infrared analysis by the Swiss cheese industry would help to streamline quality assurance.

Application of infrared microspectroscopy and multivariate analysis for monitoring the effect of adjunct cultures during Swiss cheese ripening.

Improved cheese flavor has been attributed to the addition of adjunct cultures, which provide certain key enzymes for proteolysis and affect the dynamics of starter and nonstarter cultures. Infrared microspectroscopy provides unique fingerprint-like spectra for cheese samples and allows for rapid monitoring of cheese composition during ripening. The objective was to use infrared microspectroscopy and multivariate analysis to evaluate the effect of adjunct cultures on Swiss cheeses during ripening. Swiss cheeses, manufactured using a commercial starter culture combination and 1 of 3 adjunct Lactobacillus spp., were evaluated at d 1, 6, 30, 60, and 90 of ripening. Cheese samples (approximately 20 g) were powdered with liquid nitrogen and homogenized using water and organic solvents, and the water-soluble components were separated. A 3-microL aliquot of the extract was applied onto a reflective microscope slide, vacuum-dried, and analyzed by infrared microspectroscopy. The infrared spectra (900 to 1,800 cm(-1)) produced specific absorption profiles that allowed for discrimination among different cheese samples. Cheeses manufactured with adjunct cultures showed more uniform and consistent spectral profiles, leading to the formation of tight clusters by pattern-recognition analysis (soft independent modeling of class analogy) as compared with cheeses with no adjuncts, which exhibited more spectral variability among replicated samples. In addition, the soft independent modeling of class analogy discriminating power indicated that cheeses were differentiated predominantly based on the band at 1,122 cm(-1), which was associated with S-O vibrations. The greatest changes in the chemical profile of each cheese occurred between d 6 and 30 of warm-room ripening. The band at 1,412 cm(-1), which was associated with acidic AA, had the greatest contribution to differentiation, indicating substantial changes in levels of proteolysis during warm-room ripening in addition to propionic acid, acetic acid, and eye formation. A high-throughput infrared microspectroscopy technique was developed that can further the understanding of biochemical changes occurring during the ripening process and provide insight into the role of adjunct nonstarter lactic acid bacteria on the complex process of flavor development in cheeses.

Rapid prediction of composition and flavor quality of cheddar cheese using ATR-FTIR spectroscopy.

Multiple methods are required for analysis of cheese flavor quality and composition. Chromatography and sensory analyses are accurate but laborious, expensive, and time consuming. A rapid and simple instrumental method based on Fourier transform infrared (FTIR) spectroscopy was developed for simultaneous analysis of Cheddar cheese composition and flavor quality. Twelve different Cheddar cheese samples ripened for 67 d were obtained from a commercial cheese manufacturer along with their moisture, pH, salt, fat content, and sensory flavor quality data. Water-soluble components were extracted from the cheese, dried on zinc selenide FTIR crystal and scanned (4000 to 700 cm(-1)). Infrared spectra of the samples were correlated with their composition and flavor quality data to develop multivariate statistical regression and classification models. The models were validated using an independent set of ten 67-d-old test samples. The infrared spectra of the samples were well defined, highly consistent within each sample and distinct from other samples. The regression models showed excellent fit (r > 0.92) and could accurately determine moisture, pH, salt, and fat contents as well as the flavor quality rating in less than 20 min. Furthermore, cheeses could also be classified based on their flavor quality (slight acid, whey taint, good cheddar, and so on). The discrimination of the samples was due to organic acids, amino acids, and short chain fatty acids (1800 to 900 cm(-1)), which are known to contribute significantly to cheese flavor. The results show that this technique can be a rapid, inexpensive, and simple tool for predicting composition and flavor quality of cheese.

Cheddar cheese classification based on flavor quality using a novel extraction method and Fourier transform infrared spectroscopy.

Analysis of Cheddar cheese flavor using trained sensory and grading panels is expensive and time consuming. A rapid and simple solvent extraction procedure in combination with Fourier transform infrared spectroscopy was developed for classifying Cheddar cheese based on flavor quality. Fifteen Cheddar cheese samples from 2 commercial production plants were ground into powders using liquid nitrogen. The water-soluble compounds from the cheese powder, without interfering compounds such as fat and protein, were extracted using water, chloroform, and ethanol. Aliquots (10 microL) of the extract were placed on a zinc selenide crystal, vacuum dried, and scanned in the mid-infrared region (4,000 to 700 cm(-1)). The infrared spectra were analyzed by soft independent modeling of class analogy (SIMCA) for pattern recognition. Sensory flavor quality of these cheeses was determined by trained quality assurance personnel in the production facilities. The SIMCA models provided 3-dimensional classification plots in which all the 15 cheese samples formed well-separated clusters. The orientation of the clusters in 3-dimensional space correlated well with their cheese flavor characteristics (fermented, unclean, low flavor, sour, good Cheddar, and so on). The discrimination of the samples in the SIMCA plot was mainly due to organic acids, fatty acids and their esters, and amino acids (1,450 to 1,350 and 1,200 to 990 cm(-1)), which are known to contribute significantly to cheese flavor. The total analysis time, including the sample preparation time, was less than 20 min per sample. This technique can be a rapid, inexpensive, and simple tool to the cheese industry for predicting the flavor quality of cheese.

Microbiological, chemical, and sensory characteristics of Swiss cheese manufactured with adjunct Lactobacillus strains using a low cooking temperature.

The effect of nonstarter Lactobacillus adjunct cultures on the microbial, chemical, and sensory characteristics of Swiss cheese manufactured using the "kosher make procedure" was investigated. The kosher make procedure, which uses a lower cooking temperature than traditional Swiss cheese making, is used by many American cheese manufacturers to allow for kosher-certified whey. Cheeses were manufactured using a commercial starter culture combination and 1 of 3 non-starter Lactobacillus strains previously isolated from Swiss cheeses, Lactobacillus casei A26, L. casei B21, and Lactobacillus rhamnosus H2, as an adjunct. Control cheeses lacked the adjunct culture. Cheeses were analyzed during ripening for microbial and chemical composition. Adjunct strain L. casei A26, which utilized citrate most readily in laboratory medium, dominated the Lactobacillus population within 30 d, faster than the other adjunct cultures. There were no significant differences in Propionibacterium counts, Streptococcus thermophilus counts, protein, fat, moisture, salt, and pH among the cheeses. Free amino acid concentration ranged from 5 to 7 mmol/100 g of cheese at 90 d of ripening and was adjunct strain dependent. Lactic, acetic, and propionic acid concentrations were not significantly different among the cheeses after a 90-d ripening period; however differences in propionic acid concentrations were apparent at 60 d, with the cheeses made with L. casei adjuncts containing less propionic acid. Citric acid was depleted by the end of warm room ripening in cheeses manufactured with adjunct L. casei strains, but not with adjunct L. rhamnosus. Cheeses made with L. casei A26 were most similar to the control cheeses in diacetyl and butyric/isobutyric acid abundance as evaluated by electronic nose during the first 3 mo of ripening. The 4 cheese types differed in their descriptive sensory profiles at 8 mo of age, indicating an adjunct strain-dependent effect on particular flavor attributes. Adjunct Lactobacillus spp. affected the flavor profile and concentration of some flavor compounds in Swiss cheeses produced with the kosher make procedure. Use of adjunct Lactobacillus cultures provides Swiss cheese makers using a low cooking temperature with a means to control the dominant Lactobacillus strain during ripening, reduce citrate concentration, and modify cheese flavor.

Application of Fourier transform infrared spectroscopy for monitoring short-chain free fatty acids in Swiss cheese.

Short-chain free fatty acids (FFA) are important sources of cheese flavor and have been reported to be indicators for assessing quality. The objective of this research was to develop a simple and rapid screening tool for monitoring the short-chain FFA contents in Swiss cheese by using Fourier transform infrared spectroscopy (FTIR). Forty-four Swiss cheese samples were evaluated by using a MIRacle three-reflection diamond attenuated total reflectance (ATR) accessory. Two different sampling techniques were used for FTIR/ATR measurement: direct measurement of Swiss cheese slices (approximately 0.5 g) and measurement of a water-soluble fraction of cheese. The amounts of FFA (propionic, acetic, and butyric acids) in the water-soluble fraction of samples were analyzed by gas chromatography-flame ion-ization detection as a reference method. Calibration models for both direct measurement and the water-soluble fraction of cheese were developed based on a cross-validated (leave-one-out approach) partial least squares regression by using the regions of 3,000 to 2,800, 1,775 to 1,680, and 1,500 to 900 cm(-1) for short-chain FFA in cheese. Promising performance statistics were obtained for the calibration models of both direct measurement and the water-soluble fraction, with improved performance statistics obtained from the water-soluble extract, particularly for propionic acid. Partial least squares models generated from FTIR/ATR spectra by direct measurement of cheeses gave standard errors of cross-validation of 9.7 mg/100 g of cheese for propionic acid, 9.3 mg/100 g of cheese for acetic acid, and 5.5 mg/100 g of cheese for butyric acid, and correlation coefficients >0.9. Standard error of cross-validation values for the water-soluble fraction were 4.4 mg/100 g of cheese for propionic acid, 9.2 mg/100 g of cheese for acetic acid, and 5.2 mg/100 g of cheese for butyric acid with correlation coefficients of 0.98, 0.95, and 0.92, respectively. Infrared spectroscopy and chemometrics accurately and precisely predicted the short-chain FFA content in Swiss cheeses and in the water-soluble fraction of the cheese.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Enzymatic Cleaning of Cellulose Acetate Membrane Reverse Osmosis Systems.

A comparison was made of several methods of evaluating the efficacy of enzyme cleaning of a tubular reverse osmosis (RO) system: (a) flux restoration, (b) dissolved solids level in permeate during cleaning and (c) removal of the radioisotope 33P. Microbiological evaluation was used as the reference method. Volumetric flux restoration and dissolved solids levels in permeate during cleaning were of little value as indicators of cleaning efficiency. When these methods suggested adequate cleaning, subsequent swabs of equipment parts or determination of counts in permeate and/or concentrate at start-up 12-24 h after cleaning showed ineffective cleaning. Swab techniques were useful in identifying areas of concern. Addition of 33P-inorganic phosphate to whey resulted in immediate absorption of the isotope to the membrane surface. Measurement of the 33P-phosphate during cleaning provided a quantitative measure of soil removal that could not be achieved with other methods. The 33P-phosphate technique indicated that soil removal is cyclic in nature, with alternating removal and redeposition. The 33P technique, while of value only as a research tool, can be helpful in determining areas of minimum turbulence in a RO system and may be useful in evaluation and improvement of equipment design.