This work aimed to develop an edible antimicrobial coating based on a starch-chitosan matrix to evaluate its effect on minimally processed carrot by means of microbiological analyses. Coatings based on 4% yam starch (w/w) + 2% glycerol (w/w) and coatings based on 4% yam starch (w/w) + 2% glycerol (w/w) + chitosan in 0.5% and 1.5% concentrations were prepared. Samples of minimally processed carrot slices were immersed into these coatings. All the samples were placed in expanded polystyrene trays, wrapped in polyvinylchloride film and stored at 10°C/15 days. During storage, all the samples had counting <100 CFU/g for Staphylococcus aureus and <3 MPN/g for Escherichia coli. Starch + 0.5% chitosan coating controlled the growth of mesophilic aerobes, yeasts and molds and psychrotrophs during the first five days of storage, ultimately presenting reductions of only 0.64, 0.11 and 0.16 log cycles, respectively, compared to the control. Starch + 1.5% chitosan coated samples showed reductions in mesophilic aerobes, mold and yeast and psychrotrophic counting of 1.34, 2.50 and 1.30 log cycles, respectively, compared to the control. The presence of 1.5% chitosan in the coatings inhibited the growth of total coliforms and lactic acid bacteria throughout the storage period. The use of edible antimicrobial yam starch and chitosan coating is a viable alternative for controlling microbiological growth in minimally processed carrot.

Edible antimicrobial films are an innovation within the biodegradable active packaging concept. They have been developed in order to reduce and/or inhibit the growth of microorganisms on the surface of foods. This study developed an edible antimicrobial film based on yam starch (Dioscorea alata) and chitosan and investigated its antimicrobial efficiency on Salmonella enteritidis. A solution of yam starch (4%) and glycerol (2%) was gelatinized in a viscoamilograph and chitosan added at concentrations of 1%, 3% and 5%. Films with and without chitosan were produced by the cast method. To evaluate the antimicrobial activity of the films, two suspensions of S. enteritidis were used in BHI medium, corresponding to counts of 2 ¥ 10 8 and 1.1 ¥ 10 6 CFU/ml. The suspensions (50 ml) were poured into flasks. The films were cut into 5 ¥ 5 and 5 ¥ 10 cm rectangles to be used at ratios of 1 : 1 (1 cm 2 /ml microorganism suspension) and 2 : 1 (2 cm 2 /ml). The film 30 mm thick on average. As a control, pure chitosan at an amount corresponding to that contained in the 3% and 5% films (5 ¥ 10 cm) was added to flasks containing the microorganism suspension. Also, flasks containing only a suspension of S. enteritidis were used as control. The suspensions, in flasks, were kept at 37°C in a waterbath with agitation. Suspension aliquots were removed every hour for reading the optic density (OD 595 ) and plating onto PCA medium. The results showed that chitosan has a bactericidal effect upon S. enteritidis. Films treated with chitosan at different concentrations showed similar antimicrobial efficiency, in addition to being dependent on diffusion. The chitosan-treated films caused a reduction of one to two log cycles in the number of microorganisms, whereas the pure chitosan presented a reduction of four to six log cycles compared with the control and starch film. The films showed good flexibility.

This study investigated the effect of the addition of starch from “hawthorn” yam ( Dioscorea rotundata ) and “creole” yam ( Dioscorea alata ) at different concentrations (0.1%, 0.3%, and 0.5% w/w) on the physicochemical and sensory properties of stirred-type yogurt. Pectin (0.3% w/w) was used as a reference stabilizer. Yogurt with yam starch presented 13.38% less syneresis than yogurts with pectin. At the sensory level, the most accepted treatment was yogurt with “creole” yam starch at 0.1% w/w. During 21 days of storage, yogurt with yam starch (“creole” and “hawthorn”) at 0.1% w/w showed a decrease in syneresis between 7% and 8%, while in those with pectin, syneresis remained practically constant in this period. Yogurt with yam starch was characterized as a pseudoplastic fluid, with a lactic acid bacterial count according to NTC 805. Yam starch can be used as stabilizer because it improves the physicochemical, sensory, and rheological characteristics of stirred-type yogurt. Especially the “creole” yam starch (0.1% w/w), which presents the best preference by consumers.

Listeria monocytogenes is a foodborne pathogen, able to survive and proliferate at refrigeration temperatures. As a result, ready-to-eat meat products have been associated with major outbreaks. Producing meat products involves lethal preservation treatments, e.g. thermal treatments. Listeria contamination, however, may be introduced when products are sliced and packaged at retail businesses or delicatessens. In Brazil, sliced bologna is very popular at retail markets. After slicing, however, bologna has a short shelf-life. The aim of this work was to study the effects of pediocin incorporation on the load at break, water vapor permeability rate and structure, by microscopic analysis, of antimicrobial cellulosic packaging. The potential application of the developed packaging for the preservation of bologna and inhibition of Listeria biofilm formation was also studied. Cellulosic antimicrobial packaging films were produced with cellulose acetate and acetone. Pediocin (commercially available concentrate ALTA TM 2341) was incorporated at 30, 40 and 50 % w/w. The load at break of films was studied using the Universal Testing Machine (Instron) at 10 °C and 25 °C. The water vapor permeability was determined by gravimetric method. A scanning electron microscope was used to study the developed packaging structure. Antimicrobial activity of films against Listeria innoucua and L. monocytogenes was tested both in vitro and in bologna samples. Results showed that values of load at break decreased with increasing concentrations of pediocin at 10 °C and 25 °C. Regarding water vapor permeability, only the control and 50 % pediocin films presented statistical difference, with the 50 % pediocin film being more permeable. In vitro tests showed antimicrobial activity against L. innocua. Cellulosic film with 50 % pediocin reduced L. monocytogenes growth on sliced bologna by 1.2 log cycles after 9 days and prevented biofilm formation on packaging and bologna surfaces. Hence, active cellulosic films made with 50 % pediocin in the form of commercially available concentrated ALTA™ 2341 have the potential of being used in a system of hurdle technologies as a final obstacle for L. monocytogenes control in bologna preservation.

Se estudió el efecto de cuatro marcas de pan tajado blanco sobre la calidad percibida por los consumidores a través de respuestas hedónicas. Se aplicó un test ciego y otro test con información de marca a 50 consumidores utilizando una escala de 1 a 7: "me disgusta extremadamente" (valor 1) y "me gusta extremadamente" (valor 7). Los datos se analizaron con análisis de varianza (ANOVA) y Test de Duncan. La variabilidad individual de los consumidores fue evaluada aplicando un mapa de preferencia interno explicando la variación de 70.4% para el test ciego y 63.5% para el test con información. Los consumidores tuvieron correlación positiva con el primer componente principal, atribuyendo notas más elevadas para la marca X, indicando el efecto de marca. El análisis de clasificación ascendente jerárquica, generó tres clúster en el test ciego y cuatro en el test con información. El género y edad de los consumidores tuvieron un efecto sobre las respuestas hedónicas.

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