Biotechnological Approach To Preserve Fresh Pasta Quality.

Fresh pasta is highly susceptible to microbial contamination because of its high water activity and nutrient content. In this study, a new biopreservation system was examined that consists of an active sodium alginate solution containing Lactobacillus reuteri and glycerol, which was added during the production process of pasta. Our aim was to extend the fresh pasta shelf life by the in situ production of reuterin, thereby avoiding the use of thermal treatments that generally compromise food sensory characteristics. Two experimental studies were carried out with the product packaged under either ordinary or modified atmospheric conditions. Microbiological and sensory quality indices were monitored to determine the effectiveness of biopreservation on product quality during storage. The use of the active solution with L. reuteri and glycerol during the production process of pasta improved both microbial and sensory quality, particularly when combined with modified atmosphere

X-ray microtomography to study the microstructure of cream cheese-type products.

In this work, the imaging x-ray microtomography technique, new to the field of food science, was used for the analysis of fat microstructure and quantification of the fat present in cream cheese-type products. Five different types of commercially produced cheeses, chosen for their variability of texture, were used for this experiment: sample A, sample B, sample C, sample D, and sample E. Appropriate quantitative 3-dimensional parameters describing the fat structure were calculated (e.g., the geometric parameter percentage of fat volume was calculated for each image as a representation of the percentage of total fat content within the sample). The dynamic-mechanical properties of these samples were also studied using a controlled-strain rotational rheometer. Storage modulus and loss modulus were determined in a frequency range of 0.01 to 10 Hz. The strain value was obtained by preliminary strain sweep oscillatory trials to determine the linear viscoelastic region of the cream cheese-type products. Statistical correlation analysis was performed on the results to help identify any microstructural-mechanical structure relationships. The results from this study show that microtomography is a suitable technique for the microstructural analysis of fat in cream cheese-type products, as it does not only provide an accurate percentage of the volume of the fat present but can also determine its spatial distribution

Effects of natural compounds on microbial safety and sensory quality of Fior di Latte cheese, a typical Italian cheese.

This work presents a preliminary study to assess the efficiency of plant essential oils as natural food preservatives in Fior di Latte cheese. Selected compounds were directly dissolved into Fior di Latte brine. Packaged Fior di Latte samples were stored at 10 degrees C for about 6 d. The cell loads of spoilage and useful microorganisms were monitored to calculate the microbial acceptability limit. Results show that some tested compounds were not acceptable by the panel from a sensorial point of view. Most compounds did not affect the microbial acceptability limit value to a great extent, and only a few such as lemon, sage, and thyme markedly prolonged the microbial acceptability limit of the investigated fresh cheese. Moreover, the above active agents exerted an inhibitory effect on the microorganisms responsible for spoilage without affecting the dairy microflora

Biopreservation of Fior di Latte cheese

Abstract In this study a new biopreservation system consisting of an active sodium alginate coating containing Lactobacillus reuteri applied to Fior di Latte cheese was studied. The final aim was to extend cheese shelf life by the in situ production of reuterin. Experimental trials were carried out with and without glycerol. How the fermentation time could improve the production of reuterin, enabling Fior di Latte shelf life, was also assessed. To this aim, the experimental analyses were conducted in 2 different trials, using 2 different production batches of samples. In the first one, Fior di Latte samples were dipped into the active sodium alginate solution prepared on the same day of their production, whereas in the second trial, samples were dipped into the active solution prepared 48h before their production to allow a proper fermentation of the inoculated microorganism. Microbiological and sensory quality indices were monitored to prove the effectiveness of biopreservation on product quality during storage. In the first trial, the combination of the probiotic microorganism with glycerol improved the microbial quality by 1 d compared with the same active solution without glycerol, whereas the 48-h-fermented active alginate solution (second trial) showed a further improved microbial quality. The application of an active coating enriched with L. reuteri and glycerol to Fior di Latte cheese is an optimal and innovative way to preserve the product and at the same time, with a combination of an optimal fermentation time, to prolong its microbial quality and thus its shelf life

Agar hydrogel with silver nanoparticles to prolong the shelf life of Fior di Latte cheese.

The objective of this work was to evaluate the effectiveness of an antimicrobial packaging system containing active nanoparticles on the quality deterioration of Fior di Latte cheese. To this aim, 3 concentrations of silver montmorillonite embedded in agar were used. The cell loads of spoilage and useful microorganisms were monitored during a refrigerated storage period. Moreover, cheese sensory quality (i.e., odor, color, consistency, and overall quality) was evaluated by means of a panel test. Results showed that the active packaging system markedly increased the shelf life of Fior di Latte cheese, due to the ability of silver cations to control microbial proliferation, without affecting the functional dairy microbiota and the sensory characteristics of the product. The active packaging system developed in this work could be used to prolong the shelf life of Fior di Latte and boost its distribution beyond local market borders

Immobilization of lysozyme on polyvinylalcohol films for active packaging applications.

A new technique for the immobilization of lysozyme onto the surface of polyvinylalcohol films is presented. The active compound was sprayed along with a suitable bonding agent onto the surface of the cross-linked polymeric matrix. Active compound release tests determined the amount of lysozyme immobilized on the film surface. With the use of Micrococcus lysodeikticus, the antimicrobial activity of the films was determined and the results correlated with the amount of immobilized lysozyme. This new technique was effective for immobilizing the enzyme, and the developed films were active against the test microorganism. Results were compared with those obtained with a different immobilizing technique, in which the active compound was bound into the bulk of the polymeric film. As expected, the surface-immobilized lysozyme films have a higher antimicrobial activity than bulk-bound films

Shelf life of Stracciatella cheese under modified-atmosphere packaging

The aim of this work is to evaluate the shelf life of Stracciatella cheese packaged in a protective atmosphere, using 4 different CO(2):N(2):O(2) gas mixtures [50:50:0 (M1), 95:5:0 (M2), 75:25:0 (M3), and 30:65:5 (M4) vol/vol] and stored at 8 degrees C. Cheese in traditional tubs and under vacuum were used as the controls. Results showed that the modified-atmosphere packaging, in particular M1 and M2, delayed microbial growth of spoilage bacteria, without affecting the dairy microflora, and prolonged the sensorial acceptability limit

Controlled release of antimicrobial compounds from highly swellable polymers.

The suitability of antimicrobial release films made from highly swellable polymers for use in food packaging was evaluated. The possibility of modulating the release kinetics of active compounds either by regulating the degree of cross-link of the polymer matrix or by using multilayer structures was addressed. The release kinetics of lysozyme, nisin, and sodium benzoate (active compounds with different molecular weights) were determined at ambient temperature (25 degrees C). The effectiveness of the proposed active films in inhibiting microbial growth was addressed by determining the antimicrobial efficiency of the released active compounds. Micrococcus lysodeikticus, Alicyclobacillus acidoterrestris, and Saccharomyces cerevisiae were used to test the antimicrobial efficiency of released lysozyme, nisin, and sodium benzoate, respectively. Results indicate that the release kinetics of both lysozyme and nisin can be modulated through the degree of cross-link of the polymer matrix, whereas multilayer structures need to be used to control the release kinetics of sodium benzoate. All the active compounds released from the investigated active films were effective in inhibiting microbial growth