Evaluation of aeration and substrate concentration on the production of carotenoids by <Emphasis Type="Italic">Sporidiobolus salmonicolor</Emphasis> (CBS 2636) in bioreactor

This study aimed at optimising the cultivation conditions for the production of carotenoids by Sporidiobolus salmonicolor (CBS 2636) in a bioreactor. The maximum content of total carotenoids in the full factorial design 22 was 3131.3 μg/L in synthetic medium with 80 g/L of glucose, 15 g/L of peptone, 5 g/L of malt extract, aeration of 1.5 vvm, agitation of 180 rpm, initial pH of 4.0 at 25 °C. In the kinetic study, we could observe that the bioproduction of carotenoids is associated with cell growth in the exponential phase, and the average specific growth (μ) in bioreactor is 0.046 h⁻¹ with a maximum yield of 0.19 g cells/L h. The maximum yield of carotenoids (60.0 μg/Lh) is observed at 50-h bioproduction. The conversion factor for total organic carbon (TOC) in cells (Y_X/_SCOT) was 2.97 g/g (0–50 h) and 0.254 g/g (50–100 h), the conversion factor glucose into cells (Y_X/Sglicose) was 0.168 g/g (0–100 h). The specific production of carotenoids (Y_P/_X) was 390 μg of carotenoids per gram of cells, the conversion factor of carbon in the product (Y_P/SCOT) was 107.8 μg/g (0–50 h) and 34.4 μg/g (50–100 h), whereas the factor Y_P/_Sglicose was 69.59 μg/g. The agitation and aeration provided better homogeneity in the culture medium, and hence greater availability of nutrients and oxygen, leading to higher production of carotenoids.     

Performance of a New Microbial Test for Quinolone Residues in Muscle

Concerns regarding the presence of drug residues in foods include allergic reactions, toxicity, technological problems in fermented products and the development of antibiotic resistance in human pathogens. The analysis of antimicrobial residues in foods is generally carried out, in a first step, through microbiological screening tests. These tests commonly use Geobacillus stearothermophilus as target specie but show a low ability to detect quinolones. The goal of our study was to evaluate the performance of a new microbiological test (Equinox) for detection of quinolone residues in muscle. The kit contains an ampoule with a standardized number of freeze-dried Escherichia coli and must be diluted with a specific detection medium containing a redox indicator. Microbial growth will modify the redox potential of the medium being observed through a colour change (from blue to brown/orange). Equinox limits of detection for most of tested quinolones (enrofloxacin, norfloxacin, sarafloxacin, marbofloxacin, ciprofloxacin, danofloxacin and difloxacin) were below or around maximum residue limit (MRL) UE and CCβ values obtained corresponded with the determined sensitivities. In contrast, flumequine could not be detected at MRL UE levels. Moreover, Equinox displayed a low sensitivity to other antimicrobials. Sensitivity data obtained in vitro were consistent when testing incurred muscle samples. Matrix constituents, test batch and animal species did not affect the performance of the test. Equinox could be easily automated enabling a large numbers of simultaneous analysis, and a photometric reading can be applied for a precise interpretation. The results obtained in this study prove that Equinox is a useful tool when screening for quinolone residues or can be combined with other methods for screening of unknown samples.     

Composition and quality of Mexican and imported retail beef in Mexico

Randomly selected New York steaks from domestic and imported beef were purchased in three major Mexican cities, comparing Mexican beef (from northern, central, and southern regions of the country) and American beef (USDA-Choice and ungraded No Roll). The meat was analyzed for chemical composition, Warner-Bratzler shear force (WBSF), cooking loss, color and consumer acceptability. All sources of Mexican beef and No Roll US beef had similar chemical composition. USDA-Choice beef had a higher fat content and a lower moisture and total collagen content. Mexican beef from the northern region and USDA-Choice beef had lower WBSF and redness values than the other beef sources. Overall desirability was high regarding all Mexican beef sources, and USDA-Choice beef. No Roll US beef had the lowest overall desirability score. Results indicate Mexican beef is in an advantageous position when competing with imports in the current open market.     

Effect of the fungal protease EPg222 on proteolysis and texture in the dry fermented sausage ‘salchichón’

Proteolytic activity of the fungal protease EPg222 and its effect on the texture of the dry fermented sausage ‘salchichón’, which has a long ripening process, was assayed. Samples with enzyme added showed a significant reduction of myofibrillar protein concentration during the ripening period, compared with a control, and proteolytic activity of the enzyme led to a higher accumulation of non‐protein and ‐amino acid nitrogen. Analysis of volatile compounds in ripened dry fermented sausages revealed that only in EPg222 batches were branched compounds derived from amino acids catabolism detected that are associated with the flavour of dry cured meat products. The texture profile analysis showed reduction in hardness, gumminess and chewiness values in treated compared with control sausages. The effect of this enzyme could be of great interest in stimulating proteolysis, in flavour development and in reducing the hardness of dry fermented sausages produced by a long ripening process. Copyright © 2004 Society of Chemical Industry     

Reduction of Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes with electrolyzed oxidizing water on inoculated hass avocados (Persea americana var. Hass)

This study was intended to evaluate the bactericidal effect of electrolyzed oxidizing water (EOW) and chlorinated water on populations of Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes inoculated on avocados (Persea americana var. Hass). In the first experiment, inoculated avocados were treated with a water wash applied by spraying tap water containing 1 mg/liter free chlorine for 15 s (WW); WW treatment and then spraying sodium hypochlorite in water containing 75 mg/liter free chlorine for 15 s (Cl75); WW treatment and then spraying alkaline EOW for 30 s (AkEW) and then spraying acid EOW (AcEW) for 15 s; and spraying AkEW and then AcEW. In another experiment, the inoculated avocados were treated by spraying AkEW and then AcEW for 15, 30, 60, or 90 s. All three pathogen populations were lowered between 3.6 and 3.8 log cycles after WW treatment. The application of Cl75 did not produce any further reduction in counts, whereas AkEW and then AcEW treatment resulted in significantly lower bacterial counts for L. monocytogenes and E. coli O157:H7 but not for Salmonella. Treatments with AkEW and then AcEW produced a significant decrease in L. monocytogenes, Salmonella, and E. coli O157:H7 populations, with estimated log reductions of 3.9 to 5.2, 5.1 to 5.9, and 4.2 to 4.9 log CFU/cm2, respectively. Spraying AcEW for more than 15 s did not produce any further decrease in counts of Salmonella or E. coli O157:H7, whereas L. monocytogenes counts were significantly lower after spraying AcEW for 60 s. Applying AkEW and then AcEW for 15 or 30 s seems to be an effective alternative to reduce bacterial pathogens on avocado surfaces.     

Shrimp processing assessed by low field nuclear magnetic resonance, near infrared spectroscopy, and physicochemical measurements--the effect of polyphosphate content and length of prebrining on shrimp muscle

The effect of using polyphosphates during prebrining and the effect of prebrining time of cold water shrimp (Pandalus borealis) was studied with low field nuclear magnetic resonance (LF-NMR) transverse relaxation time measurements (benchtop and unilateral) and near infrared (NIR) spectroscopy with the aim of improving shrimp processing. Strong calibrations were obtained for moisture content and water-holding capacity (WHC) using the NIR technique. Multivariate analysis indicated significant correlations between benchtop NMR parameters and moisture content and WHC, as measured with physicochemical methods and NIR spectroscopy. Significant correlations were also observed between NMR parameters and muscle pH, protein content, and phosphate content. The study showed that LF-NMR contribute to improved understanding of the shrimp brining process and to improved process control on-line or at-line, especially in combination with NIR measurements. However, optimization of the unilateral device is necessary.     

Comparative effect of the addition of α-, β-, or γ-cyclodextrin on main sensory and physico-chemical parameters

Although α-, β-, and γ-cyclodextrins (CDs) have been widely used to improve the color of different fruit juices, a comparative study of the effect of these natural CDs on other properties that also influence pear juice quality, such as odor and aroma, have not been reported yet. In this study, the comparative effect of the addition of α-, β-, and γ-cyclodextrin, the only CDs authorized to be used in the food industry by U.S. Food and Drug Administration (FDA) and European Union, on the pear juice quality was evaluated for the first time. Several instrumental and sensory properties of this fruit juice, such as color, volatile composition, odor, and aroma have been evaluated in the absence and presence of α-, β-, and γ-CD. A study of the aroma profile of pear juice showed that esters, aldehydes, alcohols, and terpenes were the most important chemical families. However, the addition of α-, β-, and γ-CD had different effects on both the concentration of individual volatile compounds and their chemical grouping. Furthermore, a trained sensory panel was used to evaluate color, overall odor, overall aroma, and overall quality of pear juice in the presence or absence of CDs. PRACTICAL APPLICATION: After comparing the effects of the addition of α-, β-, and γ-CD on pear juice, our final recommendation is to add α-CD (the natural CD formed by 6 units of glucose) to pear juice because it will significantly increase the global quality of the juice by reducing its browning but without producing a significant reduction in the aroma quality.     

Effect of cofermentation of grape varieties on aroma profiles of la mancha red wines

The effect of winemaking using blends of red grape varieties cultivated in La Mancha region (Spain) on the aroma profile of wines was researched by chemical characterization. Free and glycosidically bound aroma compounds were isolated by solid phase extraction using dichloromethane and ethyl acetate, respectively, as solvents in elution and then analyzed by gas chromatography-mass spectrometry. Free and bound volatile compounds were analyzed in Cencibel, Bobal, and Moravia Agria monovarietal wines, and in 3 wines obtained with the blending of grapes: Cencibel (50%) + Bobal (50%); Cencibel (50%) + Moravía Agria (50%); Cencibel (33%) + Bobal (33%) + Moravía Agria (33%). Aroma compounds were studied in terms of odor activity values (OAVs). Ninety free aroma compounds and sixty-five bound aroma compounds were identified and quantified. The odor activity values for the different compounds were classified into 7 odorant series. The fruity and sweet series contributed most strongly to the aroma profile of all wines, independently of the winemaking technique used. In general, co-winemaking wines present a more complex chemical profile than monovarietal wines. Practical Application: Some grape varieties could benefit from this process with the presence of other varieties that might have an excess of aroma compounds. In this study, the wines were elaborated by blending different grape varieties together; this process implies co-maceration and co-fermentation steps. The co-winemaking technique could benefit from additional molecules provided by the other varieties, which results in a more complex formation than in the case of monovarietal wines. This technique provides a viable alternative to traditional winemaking methods for improving and enhancing the sensory profile of elaborated wines.     

Consumer preferences and willingness to pay for value-added chicken product attributes

A growing demand for convenient and ready-to-eat products has increased poultry processors' interest in developing consumer-oriented value-added chicken products. In this study, a conjoint analysis survey of 276 chicken consumers in Edmonton was conducted during the summer of 2009 to assess the importance of the chicken part, production method, processing method, storage method, the presence of added flavor, and cooking method on consumer preferences for different value-added chicken product attributes. Estimates of consumer willingness to pay (WTP) premium prices for different combinations of value-added chicken attributes were also determined. Participants'"ideal" chicken product was a refrigerated product made with free-range chicken breast, produced with no additives or preservatives and no added flavor, which could be oven heated or pan heated. Half of all participants on average were willing to pay 30% more for a value-added chicken product over the price of a conventional product. Overall, young consumers, individuals who shop at Farmers' Markets and those who prefer free-range or organic products were more likely to pay a premium for value-added chicken products. As expected, consumers' WTP was affected negatively by product price. Combined knowledge of consumer product attribute preferences and consumer WTP for value-added chicken products can help the poultry industry design innovative value-added chicken products. Practical Application: An optimum combination of product attributes desired by consumers for the development of a new value-added chicken product, as well as the WTP for this product, have been identified in this study. This information is relevant to the poultry industry to enhance consumer satisfaction of future value-added chicken products and provide the tools for future profit growth.     

Preservation of acidified cucumbers with a combination of fumaric acid and cinnamaldehyde that target lactic acid bacteria and yeasts

The naturally occurring compound, fumaric acid, was evaluated as a potential preservative for the long-term storage of cucumbers. Fumaric acid inhibited growth of lactic acid bacteria (LAB) in an acidified cucumber juice medium model system resembling conditions that could allow preservation of cucumbers in the presence of sodium benzoate. Forty millimolars of fumaric acid were required to inhibit growth of an extremely aciduric Lactobacillus plantarum LA0445 strain at pH 3.8. Half of this concentration was required to achieve inhibition of L. plantarum LA0445 at pH 3.5. As expected growth of the spoilage yeasts Zygosaccharomyces globiformis and Z. bailii was not inhibited by fumaric acid at near saturation concentrations in the same cucumber juice medium. To usefully apply fumaric acid as a preservative in acidified foods it will be necessary to combine it with a food grade yeast inhibitor. The antimicrobial agent, cinnamaldehyde (3.8 mM) prevented growth of Z. globiformis as well as the yeasts that were present on fresh cucumbers. Acidified cucumbers were successfully preserved, as indicated by lack of yeasts or LAB growth and microbial lactic acid or ethanol production by a combination of fumaric acid and cinnamaldehyde during storage at 30 °C for 2 mo. This combination of 2 naturally occurring preservative compounds may serve as an alternative approach to the use of sodium benzoate, potassium sorbate, or sodium metabisulfite for preservation of acidified vegetables without a thermal process. PRACTICAL APPLICATION: This study evaluates the potential application of alternative preservatives for the long-term storage of cucumbers in a reduced NaCl cover brine solution and without a thermal process.