M. Mastromatteo

Shelf life of ready to use peeled shrimps as affected by thymol essential oil and modified atmosphere packaging.

In this work the influence of different packaging strategies on the shelf life of ready to use peeled shrimps was investigated. First, the effectiveness of the coating (Coat) and the active coating loaded with different concentrations of thymol (Coat-500, Coat-1000, and Coat-1500) on the quality loss of the investigated food product packaged in air was addressed; afterwards, the thymol concentration that had shown the best performance was used in combination with MAP (5% O(2); 95% CO(2)). Microbial cell load of main spoilage microorganisms, pH and sensorial quality were monitored during the refrigerated storage. Results of the first step suggested that the sole coating did not affect the microbial growth. A slight antimicrobial effect was obtained when the coating was loaded with thymol and a concentration dependence was also observed. Moreover, the active coating was effective in minimizing the sensory quality loss of the investigated product, it was particularly true at the lowest thymol concentration. In the second step, the thymol concentration (1000 ppm) that showed the strike balance between microbial and sensorial quality was chosen in combination with MAP. As expected, MAP significantly affected the growth of the mesophilic bacteria. In particular, a cell load reduction of about 2 log cycle for the samples under MAP respect to that in air was obtained. Moreover, the MAP packaging inhibited the growth of the Pseudomonas spp. and hydrogen sulphide-producing bacteria. The MAP alone was not able to improve the shelf life of the uncoated samples. In fact, no significant difference between the control samples packaged in air and MAP was observed. Whilst, the use of coating under MAP condition prolonged the shelf life of about 6 days with respect to the same samples packaged in air. Moreover, when the MAP was used in combination with thymol, a further shelf life prolongation with respect to the samples packaged in air was observed. In particular, a shelf life of about 14 days for the active coating under MAP compared to the same samples in air (5 days) was obtained.

Combined effects of thymol, carvacrol and temperature on the quality of non conventional poultry patties.

The combined effect of thymol (0-300ppm), carvacrol (0-300ppm), and temperature (0-18°C) on the quality of non conventional poultry patties packaged in air and modified atmosphere (MAP: 40% CO(2;) 30%O(2); 30% N(2)) was investigated using a simplex centroid mixture design. The patties were monitored for microbiological (total viable count, Enterobacteriaceae, lactic acid bacteria, Pseudomonas spp.) physico-chemical (pH, colour) and sensory attributes. For the patties mixed with the antimicrobials and stored at low temperature (0-3°C) a reduction of the cell load of about 1-1.5logcfu/g was observed. The log reduction was lower at the end of storage time and decreased with the increase of the temperature. For the poultry patties packaged in MAP the higher log reduction for Pseudomonas spp. during all the storage time was observed. In both packaging atmospheres the combination of the essential oils and low temperature determined no modification for off-odour during the first 4days of storage.

Shelf life of reduced pork back-fat content sausages as affected by antimicrobial compounds and modified atmosphere packaging

The combined use of antimicrobial compounds and modified atmosphere packaging (MAP) on shelf life of reduced pork back-fat content sausages was investigated in this study. First, a pre-screening of different antimicrobial compounds and MAP was addressed. In particular, the consumer test was used as a tool to select the most pleasant antimicrobial compounds, whereas both sausage color and cell load of main spoilage microorganisms were used to choose optimal MAP. Afterwards, antimicrobial compounds (lemon alkott and thymol) and MAP (MAP1: 20% CO(2), 5% O(2), 75% N(2)) that had shown the best performance were used to run the shelf life tests. In order to assess the influence of the variables described beforehand on the shelf life of investigated sausages, the sensorial and microbiological (mesophilic and psychrotrophic bacteria, Enterobacteriaceae, Pseudomonas spp., lactic acid bacteria and coccus-shaped lactic acid bacteria) quality was monitored during storage. Results recorded in this study suggested that Pseudomonas spp. were responsible for sausage unacceptability in all samples, except for thymol and thymol-MAP samples. For these samples, the sensorial quality was the limiting factor while the microbial growth did not limit the shelf life. In particular, for thymol and thymol-MAP samples a shelf life value of more than 5 days with respect to the other samples (2 days) was obtained.

Evaluating In Vitro Antimicrobial Activity of Thymol toward Hygiene-Indicating and Pathogenic Bacteria

Results of a study of the kinetics of bacterial inhibition by thymol in order to develop appropriate applications for the compound in food systems are presented. A modeling-based approach was used to provide a quantitative description of the antimicrobial activity of thymol toward some foodborne pathogens and hygiene-indicating bacteria, which could be postprocessing contaminants of ready-to-eat meat products. The effect of the active compound on the bacterial growth was assessed from growth kinetics curves and dose-response profiles in a wide range of thymol concentrations, i.e., from 50 to 1,000 ppm. Inhibitory data were produced using a macrodilution methodology based on a turbidimetric technique. Microbial response was discussed in terms of Gompertzs parameters as well as in terms of the active concentration of thymol affecting the growth status of microbial suspension (noninhibitory concentration and MIC). Results suggested that thymol can be successfully used as an alternative antimicrobial to increase the lag time as well as to decrease the maximum value of the growth index as reached in the stationary phase of the growth cycle for all investigated bacteria. Due to their high sensitivity to the antimicrobial stress as observed at sub-MIC, it is arguably a potential use of thymol for assurance of food safety and hygiene in combination with other preservative technologies. A quantitative evaluation of the antimicrobial properties of the active compound was performed using a macrodilution methodology based on a turbidimetric technique to produce inhibitory data. Both the growth kinetics and inhibition profile in a wide range of thymol concentrations were obtained for each test bacterium, mathematically modeled, and analyzed. Noninhibitory concentration and MIC were determined to investigate both the microbial sensibility and resistance toward thymol, and Gompertzs parameters were evaluated to assess the microbial response at each phase of growth cycle. The in vitro-obtained results suggested that thymol may be successfully used as a alternative preservative to increase the lag time as well as to decrease the maximum cell load reached in the stationary phase of growth cycle for all investigated bacteria.

Combined effect of active coating and modified atmosphere packaging on prolonging the shelf life of low-moisture Mozzarella cheese

In this work, the effect of active coating on the shelf life of low-moisture Mozzarella cheese packaged in air and modified atmosphere (MAP) was studied. The active coating was based on sodium alginate (2%, wt/vol) and potassium sorbate (1%, wt/vol). The MAP was made up of 75% CO₂ and 25% N₂ (MAP1), 25% CO₂ and 75% N₂ (MAP2), or 50% CO₂ and 50% N₂ (MAP3). The product quality decay was assessed by monitoring microbiological and sensory changes during storage at 4, 8, and 14°C. Results showed that the combination of active coating and MAP was able to improve the preservation of low-moisture Mozzarella cheese. Specifically, the shelf life increased up to 160 d for samples stored at 4°C, and 40 and 11 d for those at 8 and 14°C, respectively. A faster quality decay for untreated samples packaged in air was observed. In particular, the Pseudomonas spp. growth and the appearance of molds were responsible for product unacceptability. The combination of active coating and MAP represents a strategic solution to prolong the shelf life of low-moisture Mozzarella cheese and to ensure the safety of the product under thermal abuse conditions.

Packaging optimisation to prolong the shelf life of fiordilatte cheese

In this work, an active coating and modified atmosphere packaging (MAP) were investigated to prolong the shelf life of Fiordilatte packaged in traditional brine. First, the screening of MAP was performed in order to select the best gas composition. Then, the combined effect of MAP and coating was investigated. Finally, the coating was loaded with potassium sorbate and its effects under MAP conditions were also assessed. Results highlighted that MAP was able to control growth of the main spoilage microbial group (Pseudomonas spp.); however, the solubilisation of carbon dioxide into the brine compromised Fiordilatte texture. Therefore, the presence of the active coating avoided the damage of gas solubilisation and promoted a shelf life prolongation by about 157%.

Influence of the Milk Bactofugation and Natural Whey Culture on the Microbiological and Physico-Chemical Characteristics of Mozzarella Cheese

In this work the effect of the milk bactofugation and natural whey culture on the microbiological and physicochemical quality of Mozzarella cheese was studied. To this aim, the microbiological, sensory and physico-chemical parameters of the Mozzarella cheese were monitored during the storage at 8°C. The bactofugation treatment did not significantly affect the growth of typical dairy microorganisms, while a significant decrease of Enterobacteriaceae in milk was found. The Mozzarella manufactured with natural whey culture and bactofugated milk showed a slower increase in the Pseudomonas spp. cell load during storage. Moreover, the absence of natural whey culture in the Mozzarella cheese manufacture caused a faster sensorial quality loss during storage (~4.5 days) respect to the product with natural starter (~6 days). However, the factor limiting the shelf life of Mozzarella cheese was the growth of Pseudomonas spp. In particular, a shelf life value of about 4.0 days was obtained for Mozzarella produced with bactofugated milk and natural whey culture versus 3.5 days for the control, with citric acidification, and samples manufactured with natural whey culture and no bactofugated milk. The compositional characteristics of the cheeses were influenced by the use of the natural starter, especially at the end of the storage period. In fact, the control cheese tended to lose soluble compounds (WSN and NaCl) faster and, increase in moisture content.

A new example of nanotechnology applied to minimally processed fruit: the case of fresh-cut melon.

The effects of silver nanoparticles (Ag-MMT) incorporated into an alginate-based coating applied to fresh-cut melon (Cucumismelo L.) were assessed on the product shelf life. Different concentrations of Ag-MMT nanoparticles were tested in coated melon that was packaged in an oriented polypropylene-based bag and stored at 5°C. Results showed that the active coating was effective from the microbiological and the sensory point of view, if compared to the uncoated fruit that rapidly lost the characteristics responsible for fruit acceptance. A significant shelf life prolongation was recorded from less more than 3 days of the control samples to 11 days of coated fruit, thus promoting further investigation on Ag- MMT coating as valid preservation strategy.

Effect of raw material on cooking quality and nutritional composition of durum wheat spaghetti.

Abstract In this study the effect of semolina and wholemeal flour from six durum wheat cultivars on the pasta cooking and nutritional quality was evaluated. The wholemeal spaghetti samples showed an improvement in the chemical composition (high protein and insoluble dietary fibre content) but they have a decline in the cooking quality (high cooking loss) with respect to the semolina spaghetti. In particular, the wholemeal spaghetti Cappelli and Core samples recorded the highest protein and insoluble dietary fibre content, respectively. As compared to the other samples, the wholemeal spaghetti Iride recorded a higher cooking loss. Moreover, the wholemeal spaghetti showed the lowest overall quality due to the low score of elasticity, firmness and colour. Specifically, the wholemeal Cappelli recorded a slight rise of the overall quality with respect to other wholemeal samples. In conclusion, the wholemeal spaghetti Cappelli was found to be an optimum compromise between the sensory and nutritional quality.

Modelling the interactions between Pseudomonas putida and Escherichia coli O157:H7 in fish‐burgers: use of the lag‐exponential model and of a combined interaction index

Aims:  The objective of the current study was to examine the interactions between Pseudomonas putida and Escherichia coli O157:H7 in coculture studies on fish‐burgers packed in air and under different modified atmospheres (30 : 40 : 30 O2 : CO2 : N2, 5 : 95 O2 : CO2 and 50 : 50 O2 : CO2), throughout the storage at 8°C.