Biogenic amines, total volatile base-nitrogen (TVB-N), and sensory evaluation are some of the indicators used for fish quality determination. Our objective was to evaluate the relationship among histamine, cadaverine, putrescine, TVB-N, and sensory evaluation as quality assessment tools. Two groups of six mahi-mahi fillets were refrigerated at 7°C and sampled on days 0, 2, 4, 6, 8, and 10. On day 3, histamine, cadaverine, and putrescine levels reached 5, 3, and 0.5 mg/100 g, respectively, whereas TVB-N reached 30 mg/100 g. Sensory scores were 6 to 6.5 (10 very fresh and 1 very spoiled) for odor, appearance, texture, and color. Correlations were 0.78 and 0.72 between histamine and cadaverine and histamine and putrescine, 0.74 and 0.80 between TVB-N and cadaverine and TVB-N and putrescine, and 0.75 and 0.78 between odor and putrescine and odor and cadaverine. AromaMaps showed distinct trends for deteriorating mahi-mahi ( Coryphaena hippurus ) quality.

Application of cow manure and composted manure in agricultural practice could potentially cause contamination of foodstuffs with pathogenic bacteria such as Salmonella Enteritidis and Escherichia coli O157:H7. In this study, rifampicin-resistant (Rif R ) E. coli O157:H7 and Salmonella Enteritidis at a level of 7 log CFU/g of raw compost feed were used to determine the effect of a bench-scale composting system on their survival. Rif R E. coli O157:H7 was not detected after 72 h of composting at 45°C, and Rif R Salmonella Enteritidis was not detected after 48 h. The use of selective media for enrichment failed to recover in the composting samples held at 45°C for 96 h. However, the pathogens showed no change in bacterial numbers when the composting system was held at room temperature. Thus, properly composted manure can be safely used in food crop production while minimizing the likelihood of microbial contamination.

The survival on tomato fruits ( Lycopersicum esculentum ) of a rifampicin-resistant strain of Salmonella montevideo (Centers for Disease Control and Prevention [CDC] isolate G4639), the alleged source of the 1993 multistate outbreak of salmonellosis, was affected by inoculum dose and inoculation site (unbroken surface or wounds and stem scars), as well as by the medium (distilled water, Butterfield's buffer, or trypticase soy broth [TSB]) used to deliver the bacterium, This bacterium inoculated at 4 log 10 CFU (colony forming units) per site in distilled water survived for 20 h on tomato skin. However, comparable survival occurred at the stem scars and growth cracks with smaller inoculum doses (3 log 10 CFU). The bacterial populations increased rapidly on puncture wounds and tomato slices but decreased on the unbroken surface and stem scar. With unbroken skin and approximately 4 log 10 CFU per site, the population survived for at least 48 h but could not be consistently detected after 5 days. By contrast, the stem scar population survived for at least 7 days and decreased only 1 to 2 log 10 units. The inherently low pH of the tomatoes did not inhibit bacterial growth. Treatment with 100 ppm of aqueous chlorine for up to 2 min failed to kill all bacteria at these inoculation sites. This was especially true when the bacterial suspensions were prepared in TSB. TSB supported better bacterial survival and/or growth and also protected against the bactericidal effect of aqueous chlorine.

Aspergillus candidus ATCC 44054 grown without agitation produced more kojic acid in the modified Czapek-Dox liquid medium than cultures shaken at 100 rpm. Of the three culture media tested, yeast extract-sucrose medium permitted more kojic acid production by the fungus than modified Czapek-Dox liquid medium or Tadera medium. Maximal kojic acid (57–59 mg/ml) was produced in the yeast extract-sucrose medium on days 9–12. No aflatoxin by the fungus was detected.

Studies were carried out to assess the use of high pressure CO 2 , treatment for controlling pathogenic microorganisms in model food systems. Listeria monocytogenes suspended in distilled water was completely killed after CO 2 treatment at 6.18 MPa (61.2 atm) and 35°C for 2 h. Contrary to CO 2 treatment, the use of N 2 at these experimental conditions failed to exert bactericidal effect. High pressure CO 2 treatment at 13.7 MPa (136.1 atm) and 35°C for 2 h was shown to effectively kill Salmonella in spiked chicken meat (>95%) and egg yolk (> 100%), and kill Listeria in spiked shrimp (> 99%), orange juice (> 99%), and egg yolk (> 99.4%). Such treatment was, however, less effective in killing Salmonella in a whole egg- Salmonella mixture. Furthermore, this treatment caused a twofold increase in bacterial numbers in a whole egg- Listeria mixture. N 2 gas under similar experimental conditions did not kill the spiked bacteria in these four food systems. High pressure CO 2 treatment technique could possibly be applied to reduce microbial load in some food systems.

Detoxification of aflatoxin contaminated foods has been a continuing challenge for the food industry. This article examines primarily the detoxification of aflatoxin B 1 in foods and feeds. The sensitivity of aflatoxins to physical or chemical treatments is affected by many factors including moisture content, location of the toxins in the food, forms of the food, and interactions of the toxins with food components. Thus, it is important to understand these factors before a specific detoxification method can be recommended. In addition, the use of any applicable treatment conditions should not cause undesirable alterations to the nutritional and organoleptic qualities of the foods. The combined use of physical and chemical treatment procedures appear to provide a better prospect than the use of only a single treatment procedure. A reevaluation of the present processing conditions may shed light on the development of modified procedures to effectively degrade aflatoxins in foods, while still achieving other processing objectives.

In a comparative study to determine their effectiveness for early detection of prolific histamine-producing bacteria from tuna samples, Niven's medium proved to be superior to three modifications of the medium. Presumptive colonies could be detected in 24 h on Niven's agar surface-plated and incubated at 35°C. Following confirmatory histamine determination with high performance liquid chromatography of the tuna fish infusion broth inoculated with presumptive histamine-producers and non-producers, detection rates of 95.8 and 93.9% were obtained from temperature-abused and bacteria-spiked tuna samples, respectively, using Niven's agar. The other three modifications provided much lower detection rates and higher false-positive and false-negative results than did Niven's agar.

Effects of oven and microwave roasting on aflatoxin-contaminated peanuts were studied. In artificially contaminated peanuts, oven-roasting for 30 min at 150°C or microwave-roasting for 8.5 min at 0.7 kW were equally effective in destroying 30 to 45% of AFB 1 . Analysis was performed by the Best Food method followed by thin-layer chromatography and densitospectrometry. In naturally contaminated peanuts, both oven- and microwave-roasting were equally effective in destroying 48 to 61% of AFB 1 and 32 to 40% of aflatoxin G 1 (AFG 1 ).

Coliphages recovered from 38 samples of ten different food products were characterized with regard to temperature of infectivity. High temperature (HT) phages were capable of reproduction at or above 30°C, mid temperature (MT) phages over a range of 20 to 42°C and low temperature (LT) phages at or below 20°C. The percentage of HT coliphages isolated with Escherichia coli C-3000 host were consistently higher than corresponding percentages with E. coli C host. Coliphages recovered from all products were primarily HT or MT coliphages.

The distribution of coliphages in various foods and the relationship between the incidences of coliphages and bacterial indicators were investigated. A total of 120 food samples comprising twelve products and including fresh meats, shellfish, vegetables and processed meats, were analyzed for indigenous coliphages using Escherichia coli hosts C, C-3000 and B. Bacterial analyses included enumeration of E. coli , fecal coliforms and coliforms, as well as aerobic plate counts and Salmonella analyses. Coliphages were detected (≥10 PFU/100 g) in 56% of samples and eleven of twelve products. Coliphages, E. coli , fecal coliforms and coliforms were recovered at a level of at least 30 organisms per 100 g in 43, 43, 68 and 81% of samples, with overall mean recoveries of 13, 19, 93 and 4300 organisms/100 g, respectively. Highest and lowest recoveries of coliphages and E. coli were from fresh meats and vacuum-packaged processed meats, respectively. Significant nonparametric correlations between coliphages, E. coli , fecal coliforms and coliforms were found among all food samples.

Samples of flour, corn meal, ground meat and carrots were analyzed by standard procedures for presence of fungi using both Dichloran-Rose Bengal (DRBC) and Plate Count agar with antibiotics. Bacterial contamination was so extensive with ground meat and carrot samples on DRBC that meaningful fungal counts could not be obtained. Therefore, DRBC is not recommended for routine enumeration of fungi in foods.