Enhanced microbial safety of channel catfish (Ictalurus punctatus) fillet using recently invented medium molecular weight water-soluble chitosan coating.

Chitosan with higher molecular weight exhibited higher antimicrobial efficacy against foodborne pathogens. However, the poor water solubility of higher or medium molecular weight chitosan limits its applications. To overcome the challenge, our research team searched for simple preparation procedure for fast-dissolving medium molecular weight chitosan in water. Throughout the process, we were able to obtain a higher concentration of medium molecular weight water-soluble (MMWWS) chitosan (400 kDa). The MMWWS chitosan showed physicochemical properties that are suitable for edible coating. Antibacterial activities of 400-kDa chitosan coating prepared in acetic acid (1% v/v) or aspartic acid (1% or 3% w/v) were examined. The surface of catfish cubes was inoculated with six foodborne pathogens and then coated with chitosan solutions. The survival of each pathogen was evaluated during shelf life storage. Compared with the control, 3% w/v chitosan coating in aspartic acid solution exhibited the most effective antibacterial activities among other coating treatments, completely inhibiting Vibrio parahaemolyticus on the surface of catfish. The study suggested that chitosan dissolved in aspartic acid has the potential for use as an alternative antimicrobial coating for catfish fillet.

Short communication: Sensory analysis of a kefir product designed for active cancer survivors.

Kefir is a fermented milk product that is a good source of protein and health-promoting bacteria. It has the potential to improve recovery from exercise and the health and well-being of cancer survivors. The purpose of this study was to explore cancer survivor attitudes about and acceptance of a kefir recovery beverage made from cultured milk, whole fruit, natural sweeteners, and other natural ingredients. Kefir was made by inoculating and fermenting milk with kefir grains. The kefir was then mixed with a fruit base and given to cancer survivors (n = 52) following a bout of exercise. Participants evaluated the acceptability of the beverage samples (overall appearance, aroma, taste, mouthfeel, and overall liking) using a 9-point hedonic scale, and they evaluated the smoothness using a 3-category just-about-right scale (not enough, just about right, and too much). They also expressed their physical and psychological feelings about the beverage using a 5-point scale (1 = not at all to 5 = extremely) and indicated their purchase intent using a binomial (yes/no) response. The health benefits of kefir were then explained, and participants sampled a second beverage (the same product), answering the same questions related to overall liking, feeling, and intent to purchase. We used a paired Student's t-test to compare beverage liking and emotion scores before and after participants learned about the health benefits of kefir. Data are presented as mean ± standard deviations. The beverage scored significantly higher for overall liking after the health benefits were explained (6.5 ± 1.8 and 7.0 ± 1.7 out of 9 before and after the explanation of health benefits, respectively). Participants showed a high intent to purchase before they learned about the health benefits (75% of participants indicated an intent to purchase, and 89% after they learned about the health benefits). The beverage received high scores overall and, except for an improvement in overall liking, we observed no significant differences in physical and psychological feelings before and after participants learned that it contained kefir and had potential health benefits. We found the beverage to be acceptable for consumption by cancer survivors, and the majority of participants showed an interest in purchasing for after exercise.

Short communication: The effects of frozen storage on the survival of probiotic microorganisms found in traditionally and commercially manufactured kefir.

Kefir is a fermented milk traditionally made from a unique starter culture, which consists of numerous bacteria and yeast species bound together in an exopolysaccharide matrix produced by certain lactic acid bacteria. Many health benefits are associated with traditionally produced kefir; however, bulging and leaking packaging, caused by secondary yeast fermentation during storage, has limited large-scale manufacture. Commercial kefir products have been designed to reduce these effects by using a pure starter culture consisting of a mixture of bacteria and yeast species that give a flavor similar to traditional kefir, but some health benefits may be lost in commercial production due to reduced microbial diversity and lack of beneficial exopolysaccharides. In this study, traditional and commercial kefir was frozen to study the effects of frozen storage on the viability of probiotic bacteria over time. Traditional kefir was prepared by inoculating 1L of pasteurized whole goat milk with approximately 30g of kefir grains. Commercial kefir was prepared by inoculating 1L of full-fat, pasteurized goat milk with a commercial kefir starter. The milk was allowed to ferment at room temperature (24-28°C) until pH 4.6 was reached. Samples were frozen (-8 to -14°C) immediately following the completion of fermentation and were thawed and plated for lactobacilli, lactococci, and yeasts on d 0, 7, 14, and 30 of frozen storage. Lactobacilli, lactococci, and yeasts were significantly reduced in number during frozen storage; however, the traditionally produced kefir was shown to have significantly higher counts of bacteria and yeast at each sampling. We concluded that frozen storage and the development of frozen kefir products could eliminate most packaging concerns associated with the large-scale manufacture of traditionally produced kefir, resulting in increased production and marketability of this healthful product.

The effects of postexercise consumption of a kefir beverage on performance and recovery during intensive endurance training.

This study was designed to determine whether kefir accentuates the positive health benefits assessed by measures in fitness, body composition, or both, as a measure of cardiovascular disease risk as well as the biomarker C-reactive protein (CRP). Sixty-seven adult males and females aged 18 to 24 yr were assigned to 1 of 4 groups: (1) endurance training + control beverage, (2) endurance training +kefir beverage,(3) active control + control beverage, or (4) active control + kefir beverage. The exercise groups completed 15 wk of structured endurancetraining while the active control groups maintained their usual exercise routine. Additionally, each group was assigned to either a kefir or a calorie/macronutrient matched placebo beverage that was consumed twice per week. No significant interactions were found among groups with respect to outcome variables with the exception of serum CRP. The endurance training was effective in improving 1.5-mile (2.41 km) times and kefir supplementation may have been a factor in attenuating the increase in CRP that was observed over the course of the intervention period. This preliminary study suggests that kefir may be involved in improving the risk profile for cardiovascular disease as defined by CRP.

Robustness of Salmonella loop-mediated isothermal amplification assays for food applications.

AIMS: Loop-mediated isothermal amplification (LAMP) assays have been developed recently for Salmonella detection. This study aimed at evaluating the robustness of two Salmonella LAMP assays in comparison with PCR and real-time quantitative PCR for food applications. METHODS AND RESULTS: Performance of the assays was examined under abusive preparation conditions, running temperatures and pH, and with the addition of various inhibitors and food rinses. LAMP achieved robust detection under abusive assay preparation conditions (holding at 22 and 37°C for up to 30 min) and running temperatures (57-68°C). With a hot-start DNA polymerase, PCR obtained comparable results under these temperature ranges. However, PCR performed markedly poorer under abusive pH. LAMP also showed greater tolerance to potential inhibitors than PCR. When food rinses including meat juice, chicken rinse, egg homogenate and produce homogenate were added at 20% of the reaction mix, PCR amplifications were completely inhibited, but LAMP reactions were not. CONCLUSIONS: Our results demonstrated that LAMP is a robust alternative to PCR in Salmonella detection for food applications. SIGNIFICANCE AND IMPACT OF THE STUDY: This study filled important knowledge gaps regarding the robustness of Salmonella LAMP assays. The findings will help bring Salmonella LAMP assays closer to wider applications in food testing.

Effect of pH on technological parameters and physicochemical and texture characteristics of the pasta filata cheese Telita.

The objective of this study was to determine the effect of stretching pH on technological parameters and physicochemical and texture characteristics of the pasta filata cheese Telita. A no-brine cheese-making method was used to control both melting and stretching temperatures. Six vats of cheese, each with a different stretching pH (5.2, 5.3, 5.4, 5.5, 5.6, and 5.7), were made in 2h. Cheese-making was replicated using 2 different lots of milk. Differences in stretching pH significantly affected all variables evaluated; stretching temperature and pH were positively correlated. Technological parameters showed an inverse relationship between pH and acidity and a direct relationship between melting and stretching temperature. The yield was highest as the pH increased and ranged from 11.4 to 12.9 kg of cheese/100 kg of milk. Physicochemical characteristics showed the following: moisture 48.1 to 53.5% (soft and semi-hard cheese), fat 46.3 to 54.9% (dry basis, full-fat cheese), minerals 2.8 to 3.5% (dry basis), calcium content 0.5 to 1.0% (dry basis), sodium 0.38 to 0.78% (dry basis), and whiteness index 77.2 to 84.5. Texture parameters showed that as the stretching pH increased, hardness increased, adhesiveness decreased, cohesiveness decreased, springiness increased, and chewiness increased. Samples were grouped based on principal component analysis. Group 1 contained cheeses at pH 5.2 and 5.3 and were better in terms of retention of components. Group 2 contained cheeses at pH 5.6 and 5.7. These cheeses attained the highest yields, were whitest, and presented the highest values for texture parameters except for adhesiveness and cohesiveness. The third group of cheeses at pH 5.4 and 5.5 were considered the best because they showed a good balance among all variables evaluated.

Evaluation of diffusion and dilution methods to determine the antimicrobial activity of water-soluble chitosan derivatives.

AIMS: Chitosan has gained wide applications in the food industry and biomedical field owing to its biodegradability, biocompatibility, nontoxicity and its antimicrobial activity against a wide spectrum of micro-organisms. However, the methods used to investigate antimicrobial effects of chitosan vary considerably among studies, making comparisons difficult. METHODS AND RESULTS: One diffusion (disc diffusion) and two dilution (agar dilution and broth microdilution) methods commonly used in clinical laboratories to assess microbial susceptibility/resistance to antimicrobial agents were comparatively used to determine the antimicrobial activity of two water-soluble chitosan derivatives (molecular weights of 43 and 67 kDa) against 31 representative foodborne pathogens. When tested at 1.6% for the 43-kDa chitosan and 3.2% for the 67-kDa chitosan, by disc diffusion, approximately 10- to 11-mm-diameter inhibition zones were observed for all of the bacterial groups, except for Salmonella tested for the 67-kDa chitosan where no inhibition zone was observed. By agar dilution and broth microdilution, the minimal inhibitory concentration (MIC) values varied largely dependent upon the molecular weight of chitosan, bacterial genus/species and the testing method. The agreement between MIC values obtained by the two methods was poor, with broth microdilution generally having lower MIC values than agar dilution. Regardless of the testing method, Salmonella strains were the least susceptible among Gram-negative strains for both chitosans, followed by Escherichia coli and Vibrio. CONCLUSIONS: Besides chitosan's molecular weight and bacterial genus/species, the antimicrobial activity of chitosan was also influenced largely by the susceptibility testing method used. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study that comparatively evaluated these diffusion and dilution methods, particularly two quantitative methods (agar dilution and broth microdilution), to assess the antimicrobial activity of two water-soluble chitosans against a large number of foodborne pathogens. The study highlights the need for standardized methods to be used in evaluating chitosan's antimicrobial properties in future studies.

Comparisons of chemical and physical properties of catfish oils prepared from different extracting processes.

Four different catfish oil extraction processes were used to extract oil from catfish viscera: process CF1 involved a mixture of ground catfish viscera and water, no heat treatment, and centrifugation; process CF2 involved ground catfish viscera (no added water), heat treatment, and centrifugation; process CF3 involved a mixture of ground catfish viscera and water, heat treatment, and centrifugation; process CF4 involved ground catfish viscera, enzymatic hydrolysis, and centrifugation. Chemical and physical properties of the resulting of catfish oils were evaluated. The CF4 process recovered significantly higher amounts of crude oil from catfish viscera than the other 3 extraction methods. The CF4 oil contained a higher percent of free fatty acid and peroxide values than CF1, CF2, and CF3 oils. Oleic acid in catfish oil was the predominant fatty acid accounting for about 50% of total fatty acids. Weight loss of oils increased with increasing temperatures between 250 and 500 degrees C. All the catfish oil samples melted around -32 degrees C regardless of the extraction methods. The flow behavior index of all the oil samples was less than 1, which indicated that the catfish oils exhibited non-Newtonian fluid behavior. The apparent viscosity at -5 and 0 degrees C was significantly higher (P < 0.05) than those at 5, 10, 15, 20, 25, and 30 degrees C. The average magnitude of activation energy for apparent viscosity of the oil was higher for CF2 than CF1, CF3, and CF4.

Antibacterial activity of ozone-depolymerized crawfish chitosan.

Antimicrobial activities of chitosan samples with different molecular weights (1333, 432, 201, 131, and 104 kDa) prepared by ozone treatment were examined against 2 Gram-positive bacteria (Listeria monocytogenes and Staphylococcus aureus) and 2 Gram-negative bacteria (Escherichia coli and Pseudomonas fluorescen) to investigate the effect of chitosan's molecular weight and concentration on the inhibition of bacterial growth. Antimicrobial activity of chitosan varied depending on the molecular weight, concentration of chitosan, and type of microorganism. Generally, the effectiveness of the chitosans significantly increased with increasing chitosan concentration, regardless of molecular size and types of bacteria. Chitosan with molecular weights ranging from 104 to 201 kDa showed relatively greater antimicrobial activity against L. monocytogenes, S. aureus, and P. fluorescen; whereas for E. coli, intermediate molecular weight chitosan was more effective in growth inhibition than lower or higher molecular weight chitosan particularly at 0.1% concentration.

Selected quality characteristics of fresh-cut sweet potatoes coated with chitosan during 17-day refrigerated storage.

Selected quality characteristics of fresh-cut sweet potatoes (FCSP) coated with chitosan were evaluated during 17-d refrigerated storage. The FCSP cubes were coated with a solution (1%, w/v) of chitosan having 470 or 1110 kDa. Color (L*, a*, b*) values of uncoated and chitosan-coated FCSP during storage were generally affected by storage time as well as coating treatments (P < 0.05). No significant changes in color lightness (L*) of 470 kDa-coated FCSP were observed during the 17-d storage. During days 3 to 17, 470 kDa-coated FCSP had significantly higher redness (a*) and yellowness (b*) values than did uncoated and 1110 kDa-coated FCSP. Texture firmness of uncoated and chitosan-coated FCSP exhibited minimal changes during the 17-d storage. Although actual weight loss values (%) of uncoated and chitosan-coated FCSP were not significantly different at day 17, the weight loss difference (%) between day 3 and day 17 for uncoated FCSP (3.02%) was slightly higher compared to those (2.24% to 2.26%) of chitosan-coated FCSP. The initial total aerobic count was 4.7 log(10) CFU/g which then gradually increased to 8.54 and 9.67 log(10) CFU/g after 17 d of storage for 470 kDa-coated and uncoated FCSP, respectively. After day 6, the total aerobic counts of uncoated FCSP were higher than those of 470 kDa-coated FCSP. The yeast and mold count of chitosan-coated FCSP was about 2.5 log(10) CFU/g at day 17. Overall, consumers could not differentiate between 470 kDa-coated FCSP at day 17 and uncoated FCSP at day 0.

Plasticizer types and coating methods affect quality and shelf life of eggs coated with chitosan.

Effects of different plasticizer types (glycerol, propylene glycol, and sorbitol) and coating methods (brushing, dipping, and spraying) on the internal quality and shelf life of chitosan-coated eggs were evaluated during 5 wk of storage at 25 degrees C. The Haugh unit and yolk index values suggested that chitosan coating, irrespective of the plasticizer types, extended the shelf life of eggs by almost 3 wk at 25 degrees C compared with noncoated eggs. After 5 wk of storage, plasticizer types did not significantly affect the quality (weight loss, Haugh unit, and yolk index) of chitosan-coated eggs. However, there was an observable trend indicating that use of sorbitol rather than propylene glycol and glycerol as a plasticizer was better in reducing weight loss (whole egg) of chitosan-coated eggs during a 5-wk storage. After a 5-wk storage, there were no significant differences in weight loss and weight of albumen and yolk among chitosan-coated eggs, regardless of the coating methods. However, both brushing and dipping methods yielded chitosan-coated eggs with better yolk (higher yolk index values) and albumen (lower pH) qualities than did the spraying method. During 3 to 5 wk of storage, the Haugh unit values of chitosan-coated eggs by the brushing method were higher than or comparable to those by dipping or spraying. Therefore, coating of eggs with chitosan using sorbitol as a plasticizer and by the brushing method may offer a protective barrier in preserving the internal quality and thus extending shelf life of eggs.

Comparison of soybean oils, gum, and defatted soy flour extract in stabilizing menhaden oil during heating.

Capabilities of crude soy oil, degummed oil, gum, and defatted soy flour extract in preventing the oxidation of menhaden oil and its omega-3 fatty acids, DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid), during heating were evaluated. The menhaden oil mixed with defatted soy flour extract demonstrated the greatest stability by producing the lowest TBA reactive oxidation products and retaining the highest concentrations of DHA and EPA after heating at 150 degrees C for 30 min. A range of 62.8% to 71.5% of DHA and 67.7% to 75.9% of EPA remained in the fish oil with defatted soy flour extract, while only 29.9% of DHA and 37.2% of EPA were retained in the fish oil with no addition. Stabilizing capability from highest to lowest was defatted flour extract > gum > degummed oil = crude oil. The defatted flour extract had the highest level of total phenolic content (11.3 microg catechin equivalent/g), while crude oil, degummed oil, and gum contained 7.1, 6.1, and 6.0 microg catechin equivalent/g, respectively. The level of isoflavones in the defatted soy flour extract was 55 mg/g, which was over 100 times higher than in the crude oil or gum. Although isoflavones were not detected in the degummed oil, it contained the highest level of tocopherols (414 mug/g), whereas the lowest level (215 microg/g) was found in the defatted flour extract. The order of free radical scavenging capability measured from high to low was the defatted soy flour extract, crude oil, degummed oil, and gum.

Chitosan treatments affect growth and selected quality of sunflower sprouts.

The effects of chitosan molecular weights, solvent types, and concentrations of chitosan solution, and seed soaking times on growth and selected quality of sunflower sprouts were investigated. Among 5 chitosans tested (746, 444, 223, 67, and 28 kDa), 28 kDa chitosan exhibited the highest DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity both at 0.1% and 1.0% concentrations. Optimal conditions selected for cultivation of sunflower sprouts involved soaking seeds in 0.5% chitosan with 28 kDa (dissolved in 0.5% lactic acid) for 18 h. After cultivation for 6 d at 20 degrees C, sunflower seeds soaked in chitosan solution for 18 h under the optimal conditions yielded sprouts with 12.9% higher total weight and 16.0% higher germination rate, compared with those of seeds soaked in water for 18 h (control). Furthermore, the total amino acid content of the former sprouts (12098 mg/100 g) was slightly higher than that of the latter (12057 mg/100 g). Sprouting of sunflower seeds improved DPPH radical scavenging activity, probably due to the increased total phenolic, melatonin, and total isoflavone contents. Similarly, chitosan-treated sprouts exhibited slightly improved DPPH radical scavenging activity, probably due to slightly increased total phenolic and melatonin contents, and moderately increased total isoflavone content compared with those of the control. Chitosan treatment increased the total isoflavone content of sprouts by 11.8%, due mainly to the increased daidzein content, compared with that of the control.

Sensory optimization of broken-rice based snacks fortified with protein and fiber.

A 3-component mixture experiment was used to optimize the formulation of broken-rice based snack fortified with protein and fiber based on consumer sensory acceptability. Soy protein isolate and guar gum were used as a good source of protein and fiber, respectively, according to DRV (daily reference value) based on a 2000-calorie diet. A consumer panel evaluated sensory acceptability of color, crispness, and flavor, and overall liking of 12 experimental broken-rice based snack formulations. Predicted models derived from the restricted nonintercept regression analysis were used to plot mixture response surfaces (MRS) of each sensory attribute. Areas within the MRS plots having predicted acceptability scores of at least 6.5 (on a 9-point hedonic scale) for color, crispness, flavor, and overall liking were selected to derive a predicted optimum formulation range. Flavor acceptability was a limiting factor in attaining the optimum formulation range, which consisted of 40% to 48% broken-rice flour, 8% to 16% guar gum, and 20% to 33% soy protein isolate. To verify the obtained predicted models, the formulation containing 48% broken-rice flour, 8% guar gum, and 20% soy protein isolate, which was located in the optimum area, was chosen to support our effort to utilize and add value to broken rice. Selected physicochemical measurements of the chosen optimized formulation were determined. One serving size (30 g) of the chosen optimized snack product provided 6.58 g protein and 3.80 g dietary fiber, which met the US FDA definition of a good source of protein and dietary fiber.

Applications of chitosan for improvement of quality and shelf life of foods: a review.

Chitosan is a modified, natural biopolymer derived by deacetylation of chitin, a major component of the shells of crustacean. Recently, chitosan has received increased attention for its commercial applications in the biomedical, food, and chemical industries. Use of chitosan in food industry is readily seen due to its several distinctive biological activities and functional properties. The antimicrobial activity and film-forming property of chitosan make it a potential source of food preservative or coating material of natural origin. This review focuses on the applications of chitosan for improvement of quality and shelf life of various foods from agriculture, poultry, and seafood origin.

Acceptance and purchase intent of US consumers for nonwheat rice butter cakes.

This study evaluated consumer acceptance and purchase intent of nonwheat butter cake formulations prepared with Thai jasmine rice flour. Three nonwheat rice butter cakes were prepared with varying amounts of powdered emulsifier (propylene glycol ester:diacetyl tartaric acid ester of monoglyceride, 8:2) at 0% (product A), 7.5% (product B), and 15% (product C) of the margarine content (15%) in the cake formulation. A commercial wheat-based butter cake served as the control. Consumers (n= 400) evaluated acceptability of 9 sensory attributes using a 9-point hedonic scale. Overall acceptance and purchase intent were determined with a binomial (yes/no) scale. At least 81% of consumers accepted products B and C, of which 42.1% and 47%, respectively, would purchase the products if commercially available. Product A was neither liked nor disliked with an overall liking score of 5.39. The butter cake products were differentiated by textural acceptability (overall texture, softness, and moistness) with a canonical correlation of 0.71 to 0.79. Overall liking and taste influenced overall acceptance and purchase intent. Odor influenced purchase intent (P= 0.0014), but not overall acceptance. The odds ratio of overall liking was 3.462 for purchase intent, indicating the probability of the product being purchased is 3.462 times higher (than not being purchased, P < 0.0001) with every 1-unit increase of the overall liking score. Based on the logit model, overall acceptance and purchase intent could be predicted with 89.3% and 83.3% accuracy, respectively. The study demonstrated feasibility of completely substituting wheat flour with Thai jasmine rice flour for production of butter cake products acceptable to American consumers.

Antioxidant activities of different colored sweet bell peppers (Capsicum annuum L.).

Antioxidant compounds and their antioxidant activity in 4 different colored (green, yellow, orange, and red) sweet bell peppers (Capsicum annuum L.) were investigated. The total phenolics content of green, yellow, orange, and red peppers determined by the Folin-Ciocalteau method were 2.4, 3.3, 3.4, and 4.2 micromol catechin equivalent/g fresh weight, respectively. The red pepper had significantly higher total phenolics content than the green pepper. Among the 4 different colored peppers, red pepper contained a higher level of beta-carotene (5.4 microg/g), capsanthin (8.0 microg/g), quercetin (34.0 microg/g), and luteolin (11.0 microg/g). The yellow pepper had the lowest beta-carotene content (0.2 microg/g), while the green one had undetectable capsanthin and the lowest content of luteolin (2.0 microg/g). The free radical scavenging abilities of peppers determined by the 2,2'-diphenyl-1-picrylhydrazyl (DPPH) method were lowest for the green pepper (2.1 micromol Trolox equivalent/g) but not significantly different from the other 3 peppers. All 4 colored peppers exhibited significant abilities in preventing the oxidation of cholesterol or docosahexaenoic acid (DHA) (C22:6) during heating. However, these 4 peppers did not show significant differences in their abilities in preventing cholesterol oxidation. The green pepper showed slightly higher capability in preventing the oxidation of DHA compared to the other 3 peppers.

Oregano and rosemary extracts inhibit oxidation of long-chain n-3 fatty acids in menhaden oil.

Capabilities of methanol extracts from oregano and rosemary in retarding oxidation of long-chain polyunsaturated fatty acids, docosahexaenoic acid C22:6 (DHA) and eicosapentaenoic acid C20:5 (EPA), in menhaden oil were investigated. The fish oils after mixing with the extracts at different concentrations were oxidized in an accelerated study by heating at 150 degrees C for 30 min or incubating at 60 degrees C for 5 d. After heating at 150 degrees C, only 15.9% of DHA and 18.5% of EPA remained in the fish oil without extract, while 38.8% to 65.9% of DHA and 44.7% to 69.0% of EPA were retained in the fish oil mixed with 1% to 5% of oregano extract. The highest retained DHA (56.9%) and EPA (58.0%) in the fish oils mixed with rosemary extract were observed at 2.5% addition. Increasing rosemary extract to 5% lowered its capability of inhibiting DHA and EPA oxidation. After incubation at 60 degrees C for 5 d, the highest inhibition capability was also found at 2.5% of added rosemary extract, and the oil retained 88.2% DHA and 88.3% EPA. However, only 18.8% DHA and 23.6% EPA were retained in the fish oil mixed with 5% of oregano extract and no DHA and EPA were detected in the fish oil without extract after 5-d incubation at 60 degrees C. Thus, antioxidant activity of the rosemary extract was greater than that of oregano extract, but was sensitive to heat. The rosemary extract also demonstrated higher DPPH (2,2'-diphenyl-1-picrylhydrazyl) free radical scavenging capability, which was approximately 3 times higher than oregano extract, although there was no significant difference in the total phenolic contents between both extracts.

Simultaneous depolymerization and decolorization of chitosan by ozone treatment.

Currently, depolymerization and decolorization of chitosan are achieved by chemical or enzymatic methods, which are time consuming and expensive. Ozone has been shown to be able to degrade macromolecules and remove pigments due to its high oxidation potential. In this study, the effects of ozone treatment on depolymerization and decolorization of chitosan were investigated. Crawfish chitosan was ozonated in water and acetic acid solution for 0, 5, 10, 15, and 20 min at room temperature with 12 wt% gas. In this study, the effects of ozone treatment on depolymerization and decolorization of chitosan were investigated by measuring the molecular weight, viscosity, and color of chitosan. The color of ozone-treated chitosan was analyzed using a Minolta spectrophotometer. The degree of deacetylation was determined by a colloid titration method. Molecular weight of ozone-treated chitosan in acetic acid solution decreased appreciably as the ozone treatment duration increased. Ozonation for 20 min reduced the molecular weight of the chitosan by 92% (104 kDa) compared to the untreated chitosan (1333 kDa) with a decrease in viscosity of the chitosan solution. Ozonation for 5 min markedly increased the whiteness of chitosan with a molecular weight of 432 kDa; however, further ozonation resulted in development of yellowness. In the case of the ozonation in water, there were no significant differences in the molecular weight and color between ozone-treated chitosans. This study showed that ozone can be used to modify molecular weight and remove pigments of chitosan without chemical use in a shorter time and with less cost.

Identifying drivers for consumer acceptance and purchase intent of corn tortilla.

The traditional production of corn tortilla has been modified by new processing technologies to make possible a commercial-scale production; this practice has resulted in products having sensory properties different from those produced by the traditional method. There is no published information on sensory attributes driving acceptance and purchase intent of corn tortillas. Identifying sensory drivers for acceptance and purchase intent of corn tortillas will help commercially produce products that satisfy consumers' expectations. A consumer study was conducted to evaluate acceptance and purchase intent of corn tortillas and determine drivers of acceptance and purchase intent of the products. Ten samples of corn tortillas were selected to represent a variety of corn tortillas available in the Mexican market. Three hundred Mexican consumers evaluated acceptability of appearance, color, thickness, rollability, resistance to tearing, aroma, chewiness, taste and aftertaste, and overall liking using a 9-point hedonic scale. Overall acceptance and purchase intent were determined with a yes/no scale. Analysis of variance and multivariate analysis of variance revealed that consumers were able to differentiate differences in sensory acceptability among 10 samples. For example, 2 homemade and 1 small commercial-scale samples, with an overall liking score of 6.6 to 6.7, were more acceptable than others. Rollability, resistance to tearing, and chewiness were attributes underlying overall differences among 10 samples. Attributes determining overall acceptance of corn tortillas were chewiness and overall liking. Purchase intent was influenced by overall appearance, rollability, chewiness, taste, and overall liking. This study revealed critical sensory attributes and their weights given by Mexican consumers when making decisions for acceptance and purchase intent of corn tortilla.