Onofrio Corona

Diversity and technological potential of lactic acid bacteria of wheat flours

Lactic acid bacteria (LAB) were analysed from wheat flours used in traditional bread making throughout Sicily (southern Italy). Plate counts, carried out in three different media commonly used to detect food and sourdough LAB, revealed a maximal LAB concentration of approximately 4.75 Log CFU g(-1). Colonies representing various morphological appearances were isolated and differentiated based on phenotypic characteristics and genetic analysis by randomly amplified polymorphic DNA (RAPD)-PCR. Fifty unique strains were identified. Analysis by 16S rRNA gene sequencing grouped the strains into 11 LAB species, which belonged to six genera: Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Pediococcus and Weissella. Weissella cibaria, Lactobacillus plantarum, Leuconostoc pseudomesenteroides and Leuconostoc citreum were the most prevalent species. The strains were not geographically related. Denaturing gradient gel electrophoresis (DGGE) analysis of total DNA of flour was used to provide a more complete understanding of the LAB population; it confirmed the presence of species identified with the culture-dependent approach, but did not reveal the presence of any additional LAB species. Finally, the technological characteristics (acidifying capacity, antimicrobial production, proteolytic activity, organic acid, and volatile organic compound generation) of the 50 LAB strains were investigated. Eleven strains were selected for future in situ applications.

Candida zemplinina for production of wines with less alcohol and more glycerol

We developed a new protocol for winery mixed fermentations, using the selected Candida zemplinina yeast strain Cz3. The results of a two-year study, in which red musts (Merlot in 2010; Merlot, Nero d’Avola and Frappato in 2011) were inoculated with Cz3, is discussed. These wines were compared with wines obtained by inoculation with commercial Saccharomyces cerevisiae yeast strains (NDA21 and AR06 in 2010; NDA21 in 2011), or with those obtained by spontaneous fermentation (only in 2011). The inoculation of Cz3 always resulted in a two-phase fermentation: the first phase was driven by the C. zemplinina strain, while the second was dominated by the indigenous S. cerevisiae yeasts coming from the grapes and/or the winery. In both years the Cz3 wines contained less alcohol and more glycerol than those made with the commercial yeast strains or those obtained by spontaneous fermentation. Triangle tests showed that a sensorial difference between wines could only be achieved through the utilisation of Cz3.

Wine-making with protection of must against oxidation in a warm, semi-arid terroir

To protect varietal aromas from oxidation before alcoholic fermentation, two grape must samples were prepared from white grapes potentially low in copper, pre-cooled and supplemented with ascorbic acid and solid CO2 (trial ACO2) or SO2 (trial BSO2). The wines prepared from musts protected from oxidation had aroma descriptors that included “passion fruit” and “grapefruit skin”. The lower concentrations of flavanols in the ACO2 trial demonstrated that the use of solid CO2 as an oxidation preventative instead of SO2 reduced the extraction of these polyphenols from the grape solids. The higher concentration of hydroxycinnamoyl tartaric acids of the wine from the A CO2 trial with respect to BSO2 was ascribed to the lower grape polyphenoloxidase activity induced by the lower oxygen level in the A CO2 trial, or to the combination of caftaric acid quinone with the SO2 in B SO2. Although the grapes were very ripe (alcohol in wines ~ 14.5% vol), the wines made with musts prepared by the two techniques were characterised by aroma descriptors like “passion fruit” and “grapefruit skin”, and these aromas were not detected in the wines prepared from unprotected musts.

Effect of the mechanical harvest of drupes on the quality characteristics of green fermented table olives.

BACKGROUND Because of damage caused by mechanical harvesting, the drupes for table olive production are traditionally hand harvested. Until now, no data have been available on the microbiological and chemical features of mechanically harvested drupes during fermentation. RESULTS Drupes mechanically harvested and inoculated with Lactobacillus pentosus OM13 were characterized by the lowest concentrations of potential spoilage microorganisms. On the other hand, drupes mechanically harvested and subjected to spontaneous fermentation showed the highest concentration of Enterobacteriaceae and pseudomonads during transformation. The lowest decrease of pH (4.20) was registered for the trials inoculated with the starter culture. Differences in terms of volatile organic compounds were estimated among trials. Multivariate analysis showed that the olives processed from the drupes mechanically harvested and inoculated with starter were closely related to control production (drupes manually harvested) in terms of microbiological and pH values. Sensory analysis evidenced negative evaluations only for the uninoculated trials. CONCLUSION Drupes mechanically harvested and subjected to a driven fermentation with Lactobacillus pentosus OM13 determined the production of table olives with appreciable organoleptic features. Thus mechanical harvesting performed using a trunk shaker equipped with an inverse umbrella and the addition of starter lactic acid bacteria represents a valuable alternative to manual harvesting for table olive production at the industrial level.

Development of a method for the direct fermentation of semolina by selected sourdough lactic acid bacteria

Three obligately heterofermentative lactic acid bacteria (LAB) strains (Lactobacillus sanfranciscensis PON100336, Leuconostoc citreum PON10079 and Weissella cibaria PON10030) were used in this study as a multi-species starter culture for sourdough production. The starter inoculum was prepared and propagated in sterile semolina extract (SSE) broth. Acidification kinetics, microbiological counts detected on specific media for sourdough LAB, polymorphic profile comparison and species-specific PCRs evidenced a stability of the liquid inoculum over time determining its suitability for direct addition to semolina. In order to validate this innovative method for the production of durum wheat (Triticum durum Desf) sourdoughs, 15 semolinas (from ten old and five modern genotypes cultivated in Sicily, southern Italy) were used to prepare the SSEs and to produce sourdoughs and finally breads. Chemical and microbiological analyses of the sourdoughs and the evaluation of the quality parameters (weight loss, height, crumb and crust colour, image analysis and volatile organic compound generation) of the resulting breads indicated that the direct addition of the liquid inocula propagated in SSE is a valuable method to stabilise the production of sourdoughs. The differences registered during the technological characterisation of the breads were underlined by the sensory tests and the multivariate analysis and are mainly imputable to the type of semolina.

Valorization of indigenous dairy cattle breed through salami production

The aim of the research was to produce salami manufactured with meat of three different commercial categories of bovine breed: cow on retirement, beef and young bull. A total of six experimental productions, at small-scale plant, were carried out with and without starter culture inoculums. The evolution of physico-chemical parameters in all trials followed the trend already registered for other fermented meat products. Several LAB species were found during process with different levels of species diversity and frequency of isolation among inoculated (mainly Pediococcus pentosaceus and Staphylococcus xylosus) and uninoculated (mainly Enterococcus devriesei, Lactobacillus curvatus and Lactobacillus sakei) trials. Enterobacteriaceae were found at very low levels during the entire ripening period and no pathogenic bacteria were found in any samples. The multivariate analysis showed that starter inoculums and meat affected significantly the physico-chemical and the microbiological composition of salami. The sensory analysis evidenced the highest overall acceptability was displayed by salami produced with meat from cow on retirement.

Pomological Traits, Sensory Profile and Nutraceutical Properties of Nine Cultivars of Loquat (Eriobotrya japonica Lindl.) Fruits Grown in Mediterranean Area

In this paper the diversity of fruit quality within nine loquat cultivars, including five international affirmed cultivars (Algerie, Golden Nugget, Peluche, Bueno, El Buenet) and four local cultivars (Sanfilippara, Nespolone di Trabia, BRT20 and Claudia), were investigated in order to discriminate the variation in pomological characteristics, sensory profile, and antioxidant properties. Finally, to evaluate potential bioactivity, antiproliferative activity of hydrophilic extracts from loquat fruits was assessed, at dietary relevant concentrations, against three human epithelial cell lines. Even though the international cultivars confirmed an appropriate level of commercial qualities in association to high levels in antioxidant compounds, the local cultivars revealed the best performances in a wide range of chemical-physical and sensory characteristics. Concerning bioactivity, our results indicate that hydrophilic extracts from all tested cultivars showed concentration-dependent antiproliferative activity with a significant variability of effects between different cell lines and between different cultivars. HeLa cells, the most sensitive and hydrophilic extracts from Peluche, showed the highest inhibitory effect followed by Nespolone di Trabia and Claudia. The results of this trial provide useful information on the pomological traits and the not yet known specific nutritional and functional properties of loquat fruits. Our data, besides helping to promote specific local cultivars, could serve to establish a database that will permit to improve the utilization of specific genetic resources in breeding programs.

Effect of Salt Concentration and Extremely Halophilic Archaea on the Safety and Quality Characteristics of Traditional Salted Anchovies

ABSTRACT Extremely halophilic archaea (EHA) might play an important role in salted fish production. So far, limited information has been available on the effect of EHA and salt concentration on the safety and quality characteristics of salted anchovies. Eight Halobacterium salinarum strains were isolated from different sea salt samples and subjected to phenotypic and genotypic characterization. The strains were then inoculated into fresh salt before addition to anchovies. A total of 18 experimental productions were performed. The inoculated trials showed the lowest counts of undesired microorganisms. In particular, salted anchovies produced with Hbt. salinarum H11 showed the lowest histamine concentration as well as the highest sensory scores. Differences in terms of volatile organic compounds (VOCs) were estimated among trials. Furthermore, multivariate analysis showed that experimental production performed with a reduced amount of salt (175 g of sea salt per kg of anchovies) did not affect the final quality of salted anchovies. The strain Hbt. salinarum H11 produced salted anchovies with well-appreciated organoleptic features. Thus, the addition of EHA and the use of a lower amount of sea salt might represent a valuable alternative to the traditional method for production of salted anchovies.

Isolation, identification and oenological characterization of non-Saccharomyces yeasts in a Mediterranean island

We isolated, identified and characterized yeast strains from grapes, and their fermented musts, sampled in the small island of Linosa, where there are no wineries and therefore the possibility of territory contamination by industrial strains is minimal. By traditional culture‐dependent methods, we isolated 3805 colonies, distinguished by molecular methods in 17 different species. Five hundred and forty‐four isolates were analysed for the main oenological characteristics such as fermentative vigour with and without sulphites, sugar consumption and production of alcohol, volatile acidity, hydrogen sulphide, glycerol and β‐glucosidase. This analysis identified Kluyveromyces marxianus (seldomly used in winemaking) as the most interesting candidate yeast for the production of innovative wines.

Characterisation of vernaccia Nera (Vitis vinifera L.) grapes and wine

Vernaccia Nera (VN) is a minor Italian red grape cultivar whose oenological properties have not been investigated, yet. The traditional winemaking procedures with VN may include grape drying and even triple sequential fermentations, but a rational vinification approach should be based on the grape composition. Since a comprehensive characterization of VN grape is still missing, the ripening of VN grape was monitored by evaluating flavour compounds, proanthocyanidins and anthocyanins. The grapes were used to produce red wine whose chemical composition and sensory properties were assessed. Ripe VN grape contained high amounts of extractable anthocyanins (875 mg/kg). The most abundant anthocyanin was malvidin (56.6%) and high relative amounts of cumarate forms (11.3%) were also found. The grape skin showed high concentration of proanthocyanidins (2 g/kg) whose degree of polymerization was low (10.3). Epigallocatechin accounted up to 39% of the flavan-3-ol units in the skin. Flavour compounds in grape included glycosylated norisoprenoids (mainly 3-oxo-?-ionol and vomifoliolo) and benzenoids. The VN red wine showed high amount of anthocyanins, but the level of proanthocyanidins (0.93 g/L) was lower than expected. The spicy flavors were the notes mostly recognized with the sensory. Our data highlight VN grape is suitable for the production of ready-to-drink or shortly aged red wine due to the high acidity and low astringency.