The influence of additives on the rheological and sensory properties of nonfat yogurt

In this work, response surface methodology was applied to a study of the effects of the addition of skim milk powder and stabilizers on the apparent viscosity and sensory attributes of nonfat yogurt. The addition of stabilizers has been shown to produce a significant effect on sensory attributes, while high concentrations of xanthan and guar gum are seen to decrease the overall acceptability of the yogurt, with gelatin producing the higher apparent viscosity and consistency. The correlation among apparent viscosity, which is an instrumental measurement, and consistency, which is a sensory evaluation, was 0.72.     

EFFECTIVENESS OF CARNOBACTERIUM PISCICOLA LK5 FOR CONTROLLING THE GROWTH OF LISTERIA MONOCYTOGENES SCOTT A IN REFRIGERATED FOODS1

The potential for controlling the growth of Listeria monocytogenes in refrigerated foods using Carnobacterium piscicola LK5, a bacteriocin-producing strain originally isolated from raw ground beef, was studied using co-culture techniques. Eight foods, including UHT milk, canned “all-beef”dog food (cooked meat), raw ground beef, irradiation-sterilized raw ground beef, chicken roll, pasteurized crabmeat, canned creamed corn, and frankfurters, were inoculated with 10³ cfu/g L. monocytogenes Scott A, with and without 10⁴cfu/g LK5, and incubated at 5 and 19C. Samples were removed periodically and assayed for total aerobic plate count using Brain Heart Infusion Agar and L. monocytogenes using Vogel-Johnson Agar or Modified Vogel Johnson Agar. The growth of L. monocytogenes was suppressed in milk, dog food, crabmeat, creamed corn, and frankfurters stored at 5C. The microorganism was less inhibitory at 19C. In sterile raw ground beef, LK5 inactivated the pathogen at 5C and prevented its growth at 19C. No activity attributable to LK5 was observed in refrigerated nonsterile ground beef or chicken roll; however, these products did not support the psychrotrophic growth of the pathogen even in the absence of LK5. LK5 was most effective in products where the background microflora was reduced by either thermal processing or irradiation treatment. The results indicate that C. piscicola LK5 has potential as a means for preventing the growth of L. monocytogenes in a variety of refrigerated food products.     

Physicochemical and antioxidant properties of bovine caseinate hydrolysates obtained through microbial protease treatment

It is currently possible to obtain bioactive nutritional components through enzyme hydrolysis under well‐controlled and moderate conditions of pH and temperature. In this work, we aimed for the production and characterisation of bovine sodium caseinate (NaCAS) hydrolysates by means of an extracellular protease from Bacillus sp. P45. Antioxidant properties were evaluated through 2,2‐diphenyl‐1‐picrylhydrazyl and thiobarbituric acid reactive substances assays. A glucono‐δ‐lactone acid‐induced aggregation and gelation processes of the hydrolysates and their corresponding mixtures with NaCAS were also analysed. Hereby, we demonstrate that the presence of hydrolysates affects the kinetics of NaCAS aggregation processes but does not significantly alters the final state of the acid aggregates obtained.     

Mesenchymal stem cell secretome and nanotechnology: Combining therapeutic strategies

Mesenchymal stem cells (MSC) have pushed the field of stem cell-based therapies by inducing tissue regeneration, immunosuppression, and angiogenesis mainly through vesicles and soluble factors release (paracrine signaling). MSC-extracellular vesicles (MSC-EV) adaptable secretome and homing to injured sites allowed researchers to unlock a new era of cell-free based therapy. In parallel, nanoparticles (NP) have been explored in contributing to transport and drug delivery systems, giving drugs desired physical-chemical properties to exploit cell behavior. However, NPs can be quickly recognized by immune cells and cleared from circulation. In this viewpoint, we explore how combining both therapeutic strategies can improve efficacy and circumvent limitations of both therapies. MSCEV benefit from the potent MSC membrane composition, guiding chemotaxis to tumor sites, a very restricted microenvironment. MSC-EV has low immunogenicity, high stability, long half-life and can explore tissue targeting ligands as a precise drug carry, even across biological barriers. Those properties promote enhanced targeted drug delivery that can be combined with NP, exploring biological membrane production through: 1. direct cell therapy with NP-infused MSC; 2. NP-containing MSC-EV generated by NP-infused MSC; 3. by coating NP in MSC membrane (“MSC NanoGhosts”), allowing precise cargo definition without losing targeting. Therefore, nanotechnology combined with cell-based therapeutic resources can greatly improve targeted drug delivery, improving efficacy and opening a new venue of therapeutic possibilities.     

The compressive behaviour of porous copper made by the GASAR process

Recently, porous metals and ceramics have been made by melting the solid in a hydrogen atmosphere and then cooling through the eutectic point; the technique is known as the GASAR process. The size, shape, orientation and volume fraction of the pores can be controlled by the direction and rate of cooling and the pressure of the system. Here we describe the uniaxial compressive behaviour of GASAR copper with cylindrical pores oriented in the direction of loading. The elastic modulus and yield strength of the porous materials increase linearly with increasing relative density. Initial plastic deformation was found to be due to plastic yielding of the solid rather than buckling of the cells walls. The characteristic densification strain decreased linearly with increasing relative density.     

CHARACTERIZATION OF A LACTIC ACID BACTERIUM,CARNOBACTERIUM PISCICOLA LK5, WITH ACTIVITY AGAINST LISTERIA MONOCYTOGENES AT REFRIGERATION TEMPERATURES1

A lactic acid bacterium (LK5) originally isolated from raw ground beef was characterized in relation to its ability to inhibit the growth of Listeria monocytogenes. The isolate, which was identified as Carnobacterium piscicola, inhibited the growth of 17 of 21 strains of Listeria (L. monocytogenes, L. innocua, L. ivanovii, L. welshimeri, and L. grayii). Its activity was not due to either acid or hydrogen peroxide production, but was related to the production of a heat stable bacteriocin. The isolate was most active against L. monocytogenes at refrigeration temperatures due to the combined effect of the pathogen's increased susceptibility, LK5's rapid growth rate, and enhanced bacteriocin production at low temperatures. Examination of the effect of inoculum ratios in co-cultures of C. piscicola LK5 and L. monocytogenes Scott A indicated that the lactic acid bacterium was active against L. monocytogenes even when the initial level of the pathogen was 100-fold greater. Evaluation of the impact of oxygen availability, initial pH, and sodium chloride content on the effectiveness of LK5 suggested that the isolate could be used to suppress the growth of Listeria in a variety of refrigerated foods.     

Sex Determination on Samples of Bovine Meat by Polymerase Chain Reaction

A simple method for determining sex on samples of bovine meat is based on the polymerase chain reaction (PCR) amplification of bovine Y chromosome-specific sequences using total DNA from meat as template. Under optimized PCR conditions, an amplified DNA fragment, with size between 298 bp and 344 bp markers, was detected only in the presence of male meat DNA as template. The procedure, including DNA extraction, PCR amplification and electrophoretic analysis, required about 5 hr and could be carried out starting from fresh or frozen beef. Unambiguous results were obtained in the presence of amounts of template DNA ranging from 0.01 to 100 ng. This procedure has potential application in regulatory analysis to specifically differentiate sex origination of meat samples.