Aldo Todaro

Preliminary characterization of wild lactic acid bacteria and their abilities to produce flavour compounds in ripened model cheese system

Aims:  The aim of this work was to preliminary characterize wild lactic acid bacteria (LAB), previously isolated during artisanal Pecorino Siciliano (PS) cheese‐making for technological and flavour formation abilities in a model cheese system.

Study and characterization of polyphenol oxidase from eggplant (Solanum melongena L.).

In this study the catecholase and cresolase activities of eggplant polyphenol oxidase (PPO) were investigated. Enzyme activity was determined by measuring the increase in absorbance using catechol as substrate and 3-methyl-2-benzothiazolinone hydrazone (MBTH) as coupled reagent. The effects of substrate specificity, heat inactivation, temperature, pH, and inhibitors were investigated to understand the enzymatic alteration of ready-to-eat preparations. Browning of vegetables was determined through a colorimeter. Decrease of lightness (L*) and increase of color difference values (ΔE*) were correlated with tissue browning. Antibrowning agents were tested on PPO under the same conditions. The enzyme activity was strongly inhibited by 0.4 M citric acid. Under natural pH conditions, the enzyme was also inhibited by tartaric acid and acetic acid. All of the results were used to understand the best conditions for food transformation (ready-to-eat and grilled eggplant slices).

Polyphenol Oxidase Activity from Three Sicilian Artichoke [Cynara cardunculus L. Var. scolymus L. (Fiori)] Cultivars: Studies and Technological Application on Minimally Processed Production

Several papers helped with the development of more methods to control browning, or study thermal polyphenol oxidase (PPO) inactivation, but did not provide any solutions to technological process problems and food process improvement. Artichokes [ Cynara cardunculus L. var. scolymus L. (Fiori)] are susceptible to browning; this alteration could affect and reduce the suitability for its use, fresh or processed. Within this study, the catecholase and cresolase activities of PPO from three different Sicilian artichokes cultivar were characterized with regard to substrate specificity and enzyme kinetics, optimum pH and temperature, temperature and pH stability, and inhibitor test; all of the results were used for technological purposes, particularly to optimize minimally processed productions (ready-to-eat and cook-chilled artichokes).

Effect of freezing/thawing process in different sizes of blue fish in the Mediterranean through lysosomal enzymatic tests.

The assessment of freshness of different sizes of blue fish (Engraulis encrasicolus 12 cm, Sardina pilchardus 15 cm, Trachurus trachurus 40 cm, Scomber japonicus colias 60 cm) was carried out using non-conventional enzymatic methods. The activities of the three lysosomal enzymes (α-glucosidase (AG), β-galactosidase (B-GAL) and β-N-acetylglucosamidase (B-NA)) in extracts of blue fish muscle were measured over a period of 21 days of storage. A significant increase (p<0.05) of AG activity was observed in all species, with a large increase seen after only one day of storage. B-NA activity increased slightly in sardines, horse mackerels and chub mackerel during frozen/thawed storage. Finally, the increase of B-GAL activity was significant (p<0.05) only in the samples of larger blue fish as horse mackerel and chub mackerel. All of these enzyme activities may be helpful predictive markers to limit fraud in these species.

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.

Methods used to evaluate the peroxyl (ROO·) radical scavenging capacities of four common antioxidants

Different methods that are used to measure peroxyl radical (ROO·) scavenging capacity were used in model systems containing four common antioxidant compounds: ascorbic acid, cysteine, gallic acid and Trolox, a water-soluble vitamin E analogue. Five tests were performed, with differences in the method of peroxyl radical generation (lipoxygenase, azo-compound thermal degradation and spontaneous oxidation from a natural source of fatty acids) and in the addition of probes such as linoleic acid, crocin, fluorescein and electron paramagnetic resonance (EPR) by spin-trapping with α-phenyl-N-tert-butyl-nitrone. Significant differences were found in antioxidant reactivity, evaluated by dose–effect semi-logarithmic plots and EC50 values, and a possible explanation for these differences was explored. In assays in which ROO· was generated by the azo-compound or spontaneous oxidation, gallic acid was the most powerful antioxidant. When lipoxygenase was used to produce ROO·, ascorbic acid had the highest scavenging index, while cysteine and gallic acid had low levels of activity. Another difference was identified regarding the molecular probe: ascorbic acid and Trolox were the least reactive in the EPR system and azo-bis system with fluorescein, while in assays with crocin, these compounds had intermediate activities. Ascorbic acid and Trolox were the best antioxidants in an enzymatic-linoleic acid system, with a reciprocal ratio of 6:1, while adding crocin to the same system changed the reciprocal ratio to 2:1. A literature examination indicated that out of the antioxidant compounds tested, cysteine has the highest bond dissociation enthalpy, and this compound showed, as expected, low scavenging activity in three of the five tests in this study.

Physico-chemical properties and sensory profile of durum wheat Dittaino PDO (Protected Designation of Origin) bread and quality of re-milled semolina used for its production

To help future quality checks, we characterized the physico-chemical and sensory properties of Dittaino bread, a sourdough-based durum wheat bread recently awarded with Protected Designation of Origin mark, along with the quality features of re-milled semolina used for its production. Semolina was checked for Falling Number (533-644s), protein content (12.0-12.3g/100gd.m.), gluten content (9.7-10.5g/100gd.m.), yellow index (18.0-21.0), water absorption (59.3-62.3g/100g), farinograph dough stability (171-327s), softening index (46-66B.U.), alveograph W (193×10-4-223×10-4J) and P/L (2.2-2.7). Accordingly, bread crumb was yellow, moderately hard (16.4-27.1N) and chewy (88.2-109.2N×mm), with low specific volume (2.28-3.03mL/g). Bread aroma profile showed ethanol and acetic acid, followed by hexanol, 3-methyl-1-butanol, 2-phenylethanol, 3-methylbutanal, hexanal, benzaldehyde, and furfural. The sensory features were dominated by a thick brown crust, with marked toasted odor, coupled to yellow and consistent crumb, with coarse grain and well-perceivable sour taste and odor.

Fermentation of Nocellara Etnea table olives by functional starter cultures at different low salt concentrations

Nocellara Etnea is one of the main Sicilian cultivars traditionally used to produce both olive oil and naturally fermented table olives. In the present study, the effect of different salt concentrations on physico-chemical, microbiological, sensorial, and volatile organic compounds (VOCs) formation was evaluated in order to obtain functional Nocellara Etnea table olives. The experimental design consisted of 8 treatments as follow: fermentations at 4, 5, 6, and 8% of salt with (E1-E4 samples) and without (C1-C4 samples) the addition of starters. All the trials were carried out at room temperature (18 ± 2°C) and monitored for an overall period of 120 d. In addition, the persistence of the potential probiotic Lactobacillus paracasei N24 at the end of the process was investigated. Microbiological data revealed the dominance of lactic acid bacteria (LAB), starting from the 7th d of fermentation, and the reduction of yeasts and enterobacteria in the final product inoculated with starters. VOCs profile highlighted a high amount of aldehydes at the beginning of fermentation, which significantly decreased through the process and a concomitant increase of alcohols, acids, esters, and phenols. In particular, esters showed an occurrence percentage higher in experimental samples rather than in control ones, contributing to more pleasant flavors. Moreover, acetic acid, ethanol, and phenols, which often generate off-flavors, were negatively correlated with mesophilic bacteria and LAB. It is interesting to note that salt content did not affect the performances of starter cultures and slightly influenced the metabolome of table olives. Sensory data demonstrated significant differences among samples registering the highest overall acceptability in the experimental sample at 5% of NaCl. The persistence of the L. paracasei N24 strain in experimental samples, at the end of the process, revealed its promising perspectives as starter culture for the production of functional table olives with reduced salt content.

Effects of innovative and conventional sanitizing treatments on the reduction of Saccharomycopsis fibuligera defects on industrial durum wheat bread

Wickerhamomyces anomalus, Hyphopichia burtonii and Saccharomycopsis fibuligera are spoilage yeasts causing chalk mold defects on sliced bread packaged under modified atmosphere. The first objective of this study, carried out in a bread-making company for two consecutive years, was to genetically identify yeasts isolated from spoiled sliced bread in Modified Atmosphere Packaging (MAP) and to determine the dominant species among identified strains. The second objective was to evaluate the effects of hydrogen peroxide and silver solution 12% (HPS) treatment in the leavening cells and cooling chambers, in comparison with the conventional Ortho-Phenylphenol (OPP) fumigating treatment, on the incidence of chalk defects of the commercialized products. One-hundred percent of the isolated yeasts were identified as S. fibuligera, while H. burtonii and W. anomalus were not detected. Concerning mean water activity (aw) and moisture content values, packaged bread samples were, respectively, included in the range 0.922-0.940 and 33.40-35.39%. S. fibuligera was able to grow in a wide range of temperature (11.5 to 28.5°C) and relative humidity (70.00 to 80.17%) in the processing environments, and product aw<0.94. Compared to OPP, the combined treatment with hydrogen peroxide and silver solution, in association with MAP, reduced to a negligible level yeast contamination of industrial sliced bread. The identification of the spoilage organisms and a comprehensive understanding of the combined effects of aw, pO2/pCO2 inside the packages, environmental conditions and sanitizing treatment on the growth behaviour is essential for future development of adequate preventive process strategies against chalk mold defects.

Effects of different emulsifiers and refining time on rheological and textural characteristics of compound chocolate.

The purpose of this study was to investigate the possibility of producing reduced fat dark compound chocolate in the ball mill refiner and using some selected emulsifiers. The effects of selected emulsifiers including lecithin, Polyglycerol polyricinoleate (PGPR) and citrem in two levels and two refining times on the characteristics such as moisture, particle size, hardness and rheological properties of the samples was examined. Data analysis revealed that the Casson model was appropriate to describe the rheological behavior of the samples containing lecithin and citrem; however, Power law model was appropriate for the samples containing PGPR. The results showed that citrem is the most effective emulsifier to reduce hardness and rheological parameters such as apparent viscosity; casson viscosity and casson yield value and using citrem as a part of formulation in the production of reduced fat dark compound chocolate can solve many technological problems.