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R Lanciotti

Publications and source records attributed to R Lanciotti.

27 records · Page 2Linked to original sources
PubMed1998

Hansenula anomala as spoilage agent of cream-filled cakes.

The aims of this work were to identify the causal agents of the sporadic off-odour occurrence in Italian cream-filled cakes and to investigate the yeasts associated to various ingredients as well as the final products. In the overall production of the considered confectionery, the phenomenon was linked to a specific type of filled-cake such as the one having the hazel nut pastry as an ingredient. This ingredient as well as the final products were characterized by high frequencies of the spoilage yeast Hansenula anomala. This species, due to attributes such as osmotolerance and the ability to produce high concentration of ethyl acetate, could exercise a decisive role in the occurrence of the off-flavour.

Acetates↗
PubMed1998

Microbiological quality of filled pasta in relation to the nature of heat treatment.

The microbial population present in 49 samples of Italian industrially processed filled pasta was characterized and its changes during refrigerated storage were evaluated. The most frequently isolated species belonged to the genus Bacillus. No pathogenic organisms were isolated from the processed industrial pasta. As a consequence of the diversity of composition and thermal treatment a wide variability was observed (from less than 3 days to more than 1 month) in the shelf life at 4 degrees C of the industrial "fresh filled pasta." However, the results obtained suggested that the shelf life of the processed products depend not only on the number of surviving cells but also on the textural or microstructural changes induced by the heat treatment. Challenge tests using Staphylococcus aureus showed that even pasteurization values (P 70(10), expressed as an equivalent process time, in minutes, necessary to obtain at 70 degrees C the same lethal effect as during the actual process) not exceeding 2 were able to remarkably reduce the cell load of this organism. Subsequent growth of the surviving S. aureus cells occurred only at temperatures > 7 degrees C, particularly when the water activity (aw) values were higher than 0.97.

Food Handling↗
PubMed1996

Effects of growth conditions on the resistance of some pathogenic and spoilage species to high pressure homogenization.

The effects of chemico-physical growth conditions such as pH, temperature and water activity (aw) on lethal high homogenization pressure effects on Listeria monocytogenes, Staphylococcus aureus, Escherichia coli and Yarrowia lipolytica were investigated. The results, though based on standard media, emphasize the importance of food system composition and its thermal history on the high pressure tolerance of the microbial population.

Bacteria↗
PubMed1994

Growth modelling of Listeria monocytogenes and Yersinia enterocolitica in food model systems and dairy products.

The growth potential of Listeria monocytogenes, measured with a gaschromatographic method, was evaluated in model systems simulating dairy products in which NaCl concentration, pH and lipid concentration ranged from values corresponding to matured hard cheeses to some light cheeses and other dairy products. The growth data from the model systems, calculated on the basis of the polynomial models obtained, were compared with values observed for dairy products. Growth parameters of Yersinia enterocolitica in traditional and light cheeses were also available. The comparison between predicted and observed data suggested that individual or interactive effects of chemicophysical variables such as pH, salt and lipid concentration are not sufficient to predict the fate of L. monocytogenes in dairy products. Microstructural factors as well as the pH effect on water binding capacity of proteins could also be implicated.

Cheese↗
PubMed1994

Analysis of the interaction between autochthonous bacteria and packaging material in PVC-bottled mineral water.

A study with about 10,000 bottles produced by a mineral water company was undertaken in order to identify the causal agent of an off-odour occurrence in the bottled water. Some physiological attributes of the dominant species over an 8-month period, as well as their interaction with packaging material, were investigated. Pseudomonas maltophilia, P. acidovorans, Acinetobacter calcoaceticus var. lowffi, frequently associated with bottles having an off-odour, seemed to play a decisive role in the phenomenon due to their elevated lipolytic activity, their cell hydrophobicity and adhesivity to the PVC walls. Their ability to attack the sodium polysulfide included in the ultramarine blue dye present in PVC, transforming it to H2S was investigated.

Bacteria↗
PubMed1994

Biochemical and physiological characteristics of Yarrowia lipolytica strains in relation to isolation source.

The physiological characteristics and fatty acid composition of 40 strains of Yarrowia lipolytica isolated from irradiated poultry meat, commercial chilled foods, the superficial water of lagoons of an Italian river delta, and commercial light butter were compared. Discriminant analysis of the results permitted the 40 strains to be classified into four groups according to their isolation source. The lag phase length at 3, 5, and 7 degrees C, the proteolytic and lipolytic activities, and the growth on sorbitol, gluconate, and N-acetylglucosamine, as well as the relative percentages of C12:0, C15:0, C17:1, C18:1, C18:2, the unsaturation level, and the percentage of total odd chain fatty acids were the characteristics exhibiting the highest discriminatory power. These results indicate that the isolates are well adapted and significant biochemical characteristics may account for the success of individual strains in their original habitat.

Fatty Acids↗
PubMed1994

Influence of some selected ions on system water activity and on ethanol vapour pressure and its inhibitory action on Saccharomyces cerevisiae.

The individual and interactive effects of some ionic species on the ethanol vapour pressure in equilibrium with the system, the water activity, and the fermentative performance of Saccharomyces cerevisiae were investigated. The concentrations of the ions Ca2+, Mg2+, and NH4+ were modulated according to a central composite design, within a range of values that can be individually considered optimal for S. cerevisiae. Although the temperature and ethanol and glucose concentrations were kept constant, the initial water activity and ethanol vapour pressure of the systems were remarkably affected by the interactions between the three ions studied. The data concerning the fermentative activity emphasize the role of the physical state of ethanol. In fact, when the ethanol concentration was kept constant, the highest fermentative performances of yeast were obtained when the ethanol vapour pressure, depending particularly on the Ca2+ and Mg2+ interaction, was the lowest in the matrix of values considered.

Ethanol↗
PubMed1993

Survey of the physiological properties of the most frequent yeasts associated with commercial chilled foods.

A comparative analysis of the initial and final population of yeasts, lactic acid bacteria and psychrotrophic bacteria, in a number of chilled foods, varying in ingredients, physico-chemical characters and origin, gave evidence that yeasts could play a significant role in the spoilage. The yeast populations appeared to be unexpectedly uniform and comprised principally strains of Yarrowia lipolytica, Debaryomyces hansenii and Pichia membranaefaciens. A survey of 62 isolates, comprising physiological characteristics such as growth temperatures, proteolytic and lipolytic activities, hydrophobicity, aw and preservative tolerance, in addition to organic acid production, indicated that these dominant species have very few common characters and that they are endowed with a spoilage potential probably linked to different physiological properties. The isolates of Y. lipolytica exhibited the strongest proteolytic and lipolytic activities and a pronounced hydrophobicity while D. hansenii isolates were characterized by a high growth rate at low temperature and at intermediate aw. P. membranaefaciens isolates showed a remarkable tolerance to acetic acid as a sole selective factor. A hypothesis of separate growth loci, in multicomponent or polyphasic food systems, was formulated.

Endopeptidases↗