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Pleurotus species, commonly known as oyster mushrooms, are edible fungi cultivated worldwide. Pleurotus genus is one of most extensively studied white-rot fungi due to its exceptional ligninolytic properties. These mushrooms have the ability to colonize and degrade a wide variety of lingo-cellulosic wastes with relatively short cycle. The objective of this study was to review published research works on the effect of substrates on nutritional composition and functional property of Pleurotus ostreatus. A literature search was done on the internet and university libraries in this area. It was found that different substrates used in cultivating mushrooms do have effect on the functional, organoleptic and nutritional properties of mushrooms. This review presents a practical checklist of effect of substrates on quality of Pleurotus ostreatus that may help different users.

In questo capitolo vengono discusse le dinamiche di abbattimento della carica cellulare in seguito all'applicazione di trattamenti termici o di condizioni comunque in grado di procurare danni letali alle cellule di microorganismi di interesse alimentare. In particolare, attraverso la discussione critica delle cinetiche di abbattimento di primo ordine, su cui sono basate le decisioni operative di gran parte dell'industria alimentare, si passa alla descrizione dei modelli alternativi più diffusi, nati per spiegare la presenza di "spalle" o "code" nelle cinetiche di morte cellulare, come il modelli di Weibull, le equazioni di Gompertz e Baranyi applicate all’analisi della disattivazione cellulare, i modelli bifasici e i modelli lognormali. In questo capitolo è anche discussa la modellazione secondaria a partire dai parametri primari e la possibilità di costruire modelli in grado di descrivere l’andamento dell’abbattimento cellulare in condizioni non isotermiche. L’ultima parte del capitolo è riservata alla descrizione dei fenomeni di inattivazione, cioè della perdita di vitalità cellulare determinata dall’esposizione prolungata a fattori ambientali stressanti, e all’abbattimento del numero di cellula attraverso l’applicazione di trattamenti stabilizzanti non termici

The composition of four essential oils (EOs) extracted by hydrodistillation from plants of common use in Cameroon (Curcuma longa, Xylopia aethiopica, Zanthoxylum leprieurii L., Zanthoxylum xanthoxyloides) was assessed by gas chromatography-mass. Their bactericidal and bacteriostatic activity was tested in vitro against three food borne pathogenic bacteria: Listeria monocytogenes, Salmonella enteritidis and Staphylococcus aureus. The bacteriostatic activities of this EOs on food borne bacteria were assessed in vitro through optical density measurements. The minimal bactericidal concentrations (MBC) were determined in broth combined with a spot plating method. Z. xanthoxyloides and Z. leprieurii showed a similar composition, with a prevalence of oxygenated monoterpenes (about 58%). The EO of Z. xanthoxyloides was the most effective against the microorganisms tested. Its higher concentration of geraniol could be linked to this higher activity. In almost all cases, the MBC was higher than the maximum concentration tested (3000 ppm). Notwithstanding their low bactericidal effect, the EOs studied showed interesting inhibiting activities against the tested food borne pathogens. S. enteritidis was the most resistant to the bacteriostatic effect of the four EOs. The knowledge of the antimicrobial potential of local plant EOs used in developing countries could help in their choice and their use to improve food safety and shelf-life.

Electronic nose devices are becoming a practical tool for the identification of differences among food products badsed on their origin, intrinsic quality and process conditions. The difficulty in using such instruments is to obtain, from the sensors response patterns, suitable parameters to identify the differences among samples. In this work the electronic nose analyses, trymethilamine determination and panel test were performed on samples of three species of farmed fish []ecentrachus labrax, Sparatus aurata and Salmo salar]tored for 8 days both under ice and abuse temperature of 6°C. Data from electronic nose were analysed choosing a group of features, i.e. average of the last 5 points, maximum point, average of the whole points and average of the signal resposnse characterised by the highest variation. A polynomial regression was performed on the different features in order to identify the contribution of the sensors to the sample response patterns. The data from the best sensors were then used to create an optimum feature (mixed feature). A principal component analysis (PCA)was performed on the data of all the features and the degree of separation of the tridimensional scatterplots used as a selective tool. Based on the results obtained, the features "average of the last 5 points" and "mixed feature" gave a good discrimination of the samples, "mixed feature" being the best. The scatterplot from "mixed feature" data allowed the separation of the fish samples based on species, freshness and storage time. The evolution overtime of the scores of the PCA, accounting for the highest variation of the best two features, was correlated both with TMA content and the overall evaluation of the product given by panelists.

The aim of this work was to characterize the essential oil (EO) of Eryngium foetidum (EfEO) and assess its activity toward Listeria monocytogenes in broth and during thermal inactivation of the pathogen in pineapple juice. In this respect, EfEO was chemically characterized, and its antilisteria potential in broth as a function of pH, cell load, and EfEO concentration was assessed through a central composite design. Furthermore, the inactivation kinetics of L. monocytogenes in the juice were assessed by combining EfEO and low pasteurization temperatures. A total of 81 compounds were identified from EfEO. The reduction of pH and cell load increased EO activity. The use of only 15 ppm of EfEO during pasteurization of pineapple juice at 60°C reduced the time required for a 4-log reduction in L. monocytogenes CFU/ml by 74.9% (i.e., from 8.5 to 2.1 min) compared with treatment without EfEO. It could be concluded that EfEO activity toward L. monocytogenes increases with the reduction of pH and that it can be used at sublethal concentrations in combination with low temperatures in pineapple juice pasteurization. This study demonstrates that EO-assisted pasteurization is a promising strategy for the reduction of thermal impact during juice production. EfEO is easily available and compatible with many juices and is thus promising for industrial application.

An implemented GC method to separate and quantify the cell cyclopropane fatty acids lactobacillic (C19cyc11) and dehydrosterculic (C19cyc9) was used to study the adaptive response to sublethal acid and cold stresses in Lactobacillus helveticus and Lactobacillus sanfranciscensis . The comparison of the composition of cellular fatty acids of the two strains and their changes after 2 h of stress exposure under micro-aerobic and anaerobic conditions indicated that the aerobic biosynthetic pathway for unsaturated fatty acids is prevalent in L. sanfranciscensis , while the anaerobic pathway is prevalent in L. helveticus . Indeed in the latter strain, in the presence of a source of oleic acid and under micro-aerobic conditions, C18:1n11 and its post-synthetic derivative C19cyc11 accounted for overall proportion ranging from 52 to 28% of the total FAs. On the other hand L. sanfranciscensis synthesizes by aerobic pathway C18:1n9 and transforms it to C19cyc9. However in this species the cumulative level of these two FAs did not exceed 30%. The relevant proportion of dodecanoic acid in the latter species suggests that carbon chain shortening is the principal strategy of L. sanfranciscensis to modulate fluidity or chemico-physical properties of the membranes.

This experimental work aimed to evaluate the potential of high pressure homogenization (HPH) to inactivate Saccharomyces cerevisiae 635 inoculated both in apricot and carrot juices. The sensitivity of the yeast was evaluated both in relation to its initial inoculum level (about 3.0 and 6.0 Log(10) cfu/ml) and number of passes applied at 100 MPa. Moreover, the effects of repeated pressure treatments at 100 MPa were evaluated for pH, water activity and viscosity of carrot and apricot juices. Data obtained showed that repeated high pressure homogenization passes at 100 MPa allowed a significant inactivation of the spoilage yeast inoculated in both juices. However, as expected, the inactivation of the considered strain was greatly affected by the food matrix. In fact, a higher viability loss of S. cerevisiae 635 was observed in carrot juice than in apricot juice. Concerning the recovery, data obtained showed that the decrease of the inoculum level to 3.0 Log(10) cfu/ml prevented (at least for 6 days) cell proliferation in the samples of apricot and carrot juices treated with more than four and seven passes, respectively. Also the refrigeration of the treated samples prevented cell recovery and, in some cases, induced a further decrease in cell viability also in the samples inoculated with 6.0 Log(10) cfu/ml allowing a further increase in the juice shelf-life. An interesting and promising result was the enhanced viscosity of apricot juices treated up to five passes at 100 MPa.

Different lagoon grey mullets such as Liza ramada (thinlip mullet), Liza aurata (golden grey mullet), and Liza saliens (leaping grey mullet) were analyzed for their nutritional, microbiological, and safety parameters. The microbiological values never exceeded the lower limits stipulated by the Italian Higher Institute of Health. The pathogenic species frequently associated with seafood (Salmonella, Listeria monocytogenes, Vibrio cholerae, Vibrio parahaemolyticus, and Aeromonas hydrophila) were never detected. The absence of coliforms and of Escherichia coli was noted in all fish species after 4 days of storage in ice. Heavy metals such as cadmium and mercury were always below the detection limits (0.01 mg/kg). All three fish species had low levels of total biogenic amines (80 to 100 mg/kg), and the presence of histamine was sporadic. All Liza species, particularly L. ramada and L. saliens, are a good source of omega3 long-chain polyunsaturated fatty acids.