Effect of Water Activity and Packaging Material on the Quality of Dehydrated Taro (Colocasia esculenta (L.) Schott) Slices during Accelerated Storage.

The quality of dehydrated taro slices in accelerated storage (45°C and 75% RH) was determined as a function of initial water activity (aw) and package type. Color, rehydration capacity, thiamin content, and α-tocopherol content were monitored during 34 weeks of storage in polyethylene and foil laminate packaging at initial storage aw of 0.35 to 0.71. Initial aw at or below 0.54 resulted in less browning and higher rehydration capacity, but not in significantly higher α-tocopherol retention. Foil laminate pouches resulted in a higher rehydration capacity and increased thiamin retention compared to polyethylene bags. Type of packaging had no effect on the color of the samples. Product stability was highest when stored in foil laminate pouches at 0.4aw. Sensory panels were held to determine the acceptability of rehydrated taro slices using samples representative of the taro used in the analytical tests. A hedonic test on rehydrated taro's acceptability was conducted in Fiji, with panelists rating the product an average of 7.2 ± 1.5 on a discrete 9-point scale. Using a modified Weibull analysis (with 50% probability of product failure), it was determined that the shelf life of dehydrated taro stored at 45°C was 38.3 weeks.

Conditions associated with Clostridium sporogenes growth as a surrogate for Clostridium botulinum in nonthermally processed canned butter.

The objective of this study was to better understand the effect of butter composition and emulsion structure on growth and survival of Clostridium sporogenes, used as a surrogate for C. botulinum in canned butter. The lack of a thermal process step in commercially available canned butter raises questions of potential safety, because it is hermetically sealed and generally exhibits anaerobic growth conditions, which are optimal for Clostridium botulinum growth. Without thermal processing, low-acid canned foods must have inhibitory factors present to prevent C. botulinum growth. Some potential intrinsic inhibitory factors, or hurdles, within butter include: reduced water activity, acidity in cultured products, elevated salt content, and the micro-droplet nature of the aqueous phase in the butter emulsion. It was hypothesized that a normal, intact butter emulsion would have sufficient hurdles to prevent C. botulinum growth, whereas a broken butter emulsion would result in a coalesced aqueous phase that would allow for C. botulinum growth. Batch-churned butter was inoculated with C. sporogenes; butter samples with varying salt contents (0, 0.8, 1.6, and 2.4% wt/wt NaCl) were prepared and stored in coated steel cans for varying times (1 or 2 wk) and temperatures (22 or 41°C) to determine temperature and emulsion structure effects on C. sporogenes growth. Samples stored at 41°C showed a significant increase in C. sporogenes growth compared with those stored at 22°C. Furthermore, NaCl addition was found to have a significant effect on C. sporogenes growth, with 0.8% NaCl promoting more growth than 0%, but with decreases in growth observed at 1.6 and 2.4%. Uninoculated control plates were also found to have bacterial growth; this growth was attributed to other anaerobic bacteria present within the cream. It was concluded that removal of the hurdle created by the micro-droplet size of the emulsion aqueous phase could result in C. botulinum growth even at elevated salt levels and, therefore, home preparation of canned butter is not advisable. It is also possible that commercially canned butter, if heat abused, could potentially allow for C. botulinum growth and, therefore, consumption is not recommended.

ß-Galactosidase activity of commercial lactase samples in raw and pasteurized milk at refrigerated temperatures.

Many consumers are unable to enjoy the benefits of milk due to lactose intolerance. Lactose-free milk is available but at about 2 times the cost of regular milk or greater, it may be difficult for consumers to afford. The high cost of lactose-free milk is due in part to the added cost of the lactose hydrolysis process. Hydrolysis at refrigerated temperatures, possibly in the bulk tank or package, could increase the flexibility of the process and potentially reduce the cost. A rapid ß-galactosidase assay was used to determine the relative activity of commercially available lactase samples at different temperatures. Four enzymes exhibited low-temperature activity and were added to refrigerated raw and pasteurized milk at various concentrations and allowed to react for various lengths of time. The degree of lactose hydrolysis by each of the enzymes as a function of time and enzyme concentration was determined by HPLC. The 2 most active enzymes, as determined by the ß-galactosidase assay, hydrolyzed over 98% of the lactose in 24h at 2°C using the supplier's recommended dosage. The other 2 enzymes hydrolyzed over 95% of the lactose in 24h at twice the supplier's recommended dosage at 2°C. Results were consistent in all milk types tested. The results show that it is feasible to hydrolyze lactose during refrigerated storage of milk using currently available enzymes.

Change in mutagenicity in white rice after accelerated and long-term storage.

Certain reactions that occur in food during storage, such as nonenzymatic browning and lipid oxidation, form compounds that have been shown to be mutagenic. It is possible that over long storage periods, significant amounts of these products could be formed. Although some research has been published concerning the mutagenicity of foods due to processing or cooking, little research has been done regarding mutagenicity of foods stored for an extended time. The objective of this research was to determine the potential mutagenicity of white rice held in accelerated and long-term storage using the Ames Salmonella/microsome assay. Fresh long-grain white rice was packaged in foil laminate pouches and held at 60 degrees C for 18 wk. Rice stored for > 25 y in an oxygen-free environment at or below room temperature in size number 10 cans was obtained from residential storage. The standard plate-incorporation method was used to evaluate the mutagenic potential of all treatments using Salmonella typhimurium tester strains TA97a, TA98, TA100, and TA102. Samples were plated at 5 dilutions with and without rat liver S9 enzyme. A solvent control was also plated for each strain. Treatments yielding counts at least double the solvent control level were considered mutagenic. Plate counts for all treatments fell well below the required doubling of the solvent control value. White rice held in accelerated and long-term storage appears not to increase in mutagenic compounds as measured by the Ames assay, supporting its use for long-term storage purposes such as emergency preparedness and humanitarian food aid.

Contextual connections within puns: effects on perceived humor and memory.

The supposition that perceived humor or cleverness would be enhanced by adding separate content to the alternative meanings of a pun was explored, using Tom Swifties as the research vehicle. Because detecting a punning word relationship might induce arousal, requiring more effort and attentional resources for processing than noting a contextual connection, memory strength for adverbs was also examined using a recognition procedure. Five studies were conducted in which college students were asked to judge 24 Swifties (content counterbalanced across participants) in which presence of pun and context were manipulated. The punning relationship was primarily responsible for perceived humor and cleverness. Presence of a pun also enhanced memory strength (d') as long as the familiarization task focused on humor and cleverness. Coherent context enhanced perceived cleverness inconsistently. It was suggested that a coherent contextual connection may make a greater contribution in more lengthy forms of pun-based word play, such as fables or "shaggy dog" stories.

Caution! NRC as protector of worker health and safety at nuclear power plants.

Congress may soon face a decision about what agency will take responsibility for worker and facility safety at Department of Energy (DOE) sites as the DOE moves to external regulation. The Nuclear Regulatory Commission (NRC) occupies a prominent place on the short list of candidates. Thus, an examination of the NRC's historical record on health and safety, in particular, its record in protecting workers, is warranted. This look at the record shows that the NRC does not adopt a strong regulatory stance; exposure standards for workers have not changed despite evidence of harmful effects at low doses of radiation exposure; record-keeping and worker monitoring are lax; the NRC is blind to internal cultural problems; it appears more concerned about its public image than about entrenched problems; it is too lenient to the industry it is supposed to regulate. The NRC's history of recent problems has caused some critics to call for Congressional hearings or additional oversight of the agency.

Making a presumptive diagnosis of urinary tract infection by using a urinalysis performed in an on-site laboratory.

The purpose of our study was to characterize the utility of certain elements of urinalysis, singly or in combination, in identifying children with urinary tract infections (i.e., positive findings on urine culture). Laboratory results for urine specimens subjected to both urinalysis and culture in an on-site outpatient clinic (office) laboratory during a 36-month period were reviewed. All specimens were collected by one of three methods (the midstream void technique, urethral catheterization, or suprapubic aspiration of urine) from children with symptoms to assist in documenting a possible urinary tract infection. Specimen processing by certified technologists was initiated within 10 minutes of collection. Sensitivity, specificity, and positive and negative predictive values were determined for each test or combination of tests. Of 689 specimens, 102 (14.8%) had positive culture results. The combination of dipstick analysis (leukocyte esterase and nitrite tests) and of microscopic examination for bacteria had a sensitivity of 100% and a negative predictive value of 100%. The nitrite test had a specificity of 100% and a positive predictive value of 100%. We conclude that, when properly collected specimens are evaluated promptly by certified technologists, the rate of accuracy in detecting or ruling out a urinary tract infection (i.e., positive findings on urine culture) with certain elements of the urinalysis is high.