Effetto dell’estrazione a basso impatto ossidativo sulla capacità antiossidante <i>in vitro</i> e sulla qualità di oli extra-vergini di oliva della Sardegna

Milling technology has a great effect on the quality of olive oils. This paper was aimed to compare the differences in quality between two Sardinian extra virgin monovarietal oils obtained with a traditional and with a low oxidative stress technology. Peroxide value and acidity were lower in oils extracted with a low oxidative stress, which resulted in up to 114% higher total phenol content, with respect to oils obtained with the traditional technology. The low oxidative stress technology, moreover, permitted them to have significantly higher values of antioxidant activity, which is to be ascribed to the higher phenol content

Monitoring raw cork TCA content in Sardinian woodlands

The studies on stopper contamination by TCA have focused on manufacturing phase and on relations between the wine and the cork. Less numerous are the forest and environmental monitoring research useful to evaluate whether different management models of the cork stands may have an influence on the process

Analytical methods for the evaluation of α-L-fucosidase activity in sheep milk

The lack of analytical methods for measuring the activity of highly thermolable endogenous enzymes in sheep milk is a factor that hampers the protection of typical Protected Designation of Origin (PDO) dairy products made from raw milk. In order to provide a solution, this study assesses, tests, and fully validates analytical procedures for the determination of α-L-fucosidase activity in sheep milk. While the UV–VIS method has been optimized for this matrix in order to solve clarification problems before the spectrophotometric reading, a reversed phase high-performance liquid chromatography literature method proposed for bovine milk has been successfully applied also to sheep milk. Both methods have been fully validated in terms of sensitivity, linearity, precision, and accuracy, displaying low detection and quantification limits, excellent linearity over a wide enzymatic activity interval, very good repeatability and reproducibility, and the lack of any bias. The analysis of a number of real samples of whole sheep milk has allowed the evaluation of an average value (46.78 ± 5.49 U mL−1) and range (from 29.27 ± 2.60 to 72.64 ± 1.17 U mL−1) of α-L-fucosidase activity. Such activity does not seem to differ substantially from those measured for bovine milk. Finally, marked seasonal variability has been observed in this preliminary dataset

Assessment and validation of methods for the determination of γ-glutamyltransferase activity in sheep milk

The determination of enzymatic activity in sheep milk is still today a practically unexplored field of research. This study proposes and fully validates two analytical procedures (i.e. by means of UV-vis spectrophotometry and RP-HPLC methods) for the determination of γ-glutamyltransferase activity in sheep milk. Both methods are characterised by low detection and quantification limits, excellent linearity over a wide enzymatic activity interval, very good repeatability and reproducibility, and are bias-free. The RP-HPLC method provides better sensitivity and automation capability levels than that of UV-vis, and its use is hence suggested for screening purposes. These methods have been preliminarily tested with a number of real samples of whole sheep milk, obtaining an average γ-glutamyltransferase activity value of 2.93 ± 0.50 U ml−1 and a range from 2.72 ± 0.10 U ml−1 to 3.46 ± 0.11 U ml−1

Table Olives: An Overview on Effects of Processing on Nutritional and Sensory Quality

Table olives are a pickled food product obtained by a partial/total debittering and subsequent fermentation of drupes. Their peculiar sensory properties have led to a their widespread use, especially in Europe, as an appetizer or an ingredient for culinary use. The most relevant literature of the last twenty years has been analyzed in this review with the aim of giving an up-to-date overview of the processing and storage effects on the nutritional and sensory properties of table olives. Analysis of the literature has revealed that the nutritional properties of table olives are mainly influenced by the processing method used, even if preharvest-factors such as irrigation and fruit ripening stage may have a certain weight. Data revealed that the nutritional value of table olives depends mostly on the balanced profile of polyunsaturated and monounsaturated fatty acids and the contents of health-promoting phenolic compounds, which are best retained in natural table olives. Studies on the use of low salt brines and of selected starter cultures have shown the possibility of producing table olives with an improved nutritional profile. Sensory characteristics are mostly process-dependent, and a relevant contribute is achieved by starters, not only for reducing the bitterness of fruits, but also for imparting new and typical taste to table olives. Findings reported in this review confirm, in conclusion, that table olives surely constitute an important food source for their balanced nutritional profile and unique sensory characteristics

Sensory profile development for an Italian PDO ewe’s milk cheese at two different ripening times

The sensory profile technique was applied to the Italian Protected Designation of Origin (PDO) Fiore Sardo cheese, made exclusively from raw ewe's milk in artisanal farms in Sardinia. The descriptive sensory analysis was used to find the sensory attributes which characterize this PDO cheese at two different ripening times (105 and 180 days). The product specification states that the cheese must have no less than 105 days of maturation before being sold, while at more than 180 days it is usually used grated. Twelve expert panelists, whose efficacy was confirmed by variance analysis, identified and evaluated 10 sensory attributes on cheese samples: smoked and rennet for odor; sour and salty for taste, piquant for trigeminal sensation; smoked and rennet for aroma; floury, grainy and friability for texture. The judges were also asked to provide an overall evaluation of sensory typicality. Cheeses from different farms ripened for 105 days differed significantly for smoked odor, salty, grainy and typicality, whereas the cheeses ripened for 180 days were significantly different for smoked odor, piquant, friability and sensory typicality. The comparison between cheeses from the same farm at 105 and 180 days showed no significant differences

Biocontrol activity of four non- and low-fermenting yeast strains against <i>Aspergillus carbonarius</i> and their ability to remove ochratoxin A from grape juice

Aspergillus spp. infection of grape may lead to ochratoxin A (OTA) contamination in processed beverages such as wine and grape juice. The aim of the current study was to evaluate the biocontrol potential of two non-fermenting (Cyberlindnera jadinii 273 and Candida friedrichii 778) and two low-fermenting (Candida intermedia 235 and Lachancea thermotolerans 751) yeast strains against the pathogenic fungus and OTA-producer Aspergillus carbonarius, and their ability to remove OTA from grape juice. Two strains, 235 and 751, showed a significant ability to inhibit A. carbonarius both on grape berries and in in vitro experiments. Neither their filtrate nor their autoclaved filtrate culture brothwas able to prevent consistently pathogen growth. Volatile organic compounds (VOCs) produced by all four selected yeasts were likely able to consistently prevent pathogen sporulation in vitro. VOCs produced by the non-fermenting strain 778 also significantly reduced A. carbonarius vegetative growth. Three yeast strains (235, 751, and 778) efficiently adsorbed artificially spiked OTA from grape juice, while autoclaving treatment improved OTA adsorption capacity by all the four tested strains. Biological control of A. carbonarius and OTA-decontamination using yeast is proposed as an approach to meet the Islamic dietary laws concerning the absence of alcohol in halal beverages

Thermal inactivation and variability of γ-glutamyltransferase and α-<span>L</span>-fucosidase enzymatic activity in sheep milk

We present a study of the thermal inactivation and variation of activity of two enzymes in sheep milk: γ-glutamyltransferase and α-L-fucosidase. We find that the thermal treatment of milk causes inactivation of α-L-fucosidase between 57 °C and 68 °C, and γ-glutamyltransferase between 68 °C and 80 °C. In untreated sheep milk, the highest level of enzymatic activity (EA) for these two enzymes is in the pH range 5.5–6.0 and 8.0–8.5, respectively. Skimming treatment causes the loss of 35% of the activity of γ-glutamyltransferase. No differences in the EA were ascribable to the diets evaluated in this study. We observed EAs of α-L-fucosidase and γ-glutamyltransferase over the entire lactation cycle, noting that the EA of the former increased from 81 to 207 U mL−1 (average 159 ± 30 U mL−1) while the EA of the latter from 3.12 to 4.89 U mL−1 (average 3.83 ± 0.34 U mL−1). Relationships between both enzymes and selected milk parameters (lipids, proteins, lactose, urea and somatic cells) are highlighted by Principal Component Analysis

Adsorption of ochratoxin A from grape juice by yeast cells immobilised in calcium alginate beads

Grape juice can be easily contaminated with ochratoxin A (OTA), one of the known mycotoxins with the greatest public health significance. Among the different approaches to decontaminate juice from this mycotoxin, microbiological methods proved efficient, inexpensive and safe, particularly the use of yeast or yeast products. To ascertain whether immobilisation of the yeast biomass would lead to successful decontamination, alginate beads encapsulating Candida intermedia yeast cells were used in our experiments to evaluate their OTA-biosorption efficacy. Magnetic calcium alginate beads were also prepared by adding magnetite in the formulation to allow fast removal from the aqueous solution with a magnet. Calcium alginate beads were added to commercial grape juice spiked with 20μg/kg OTA and after 48h of incubation a significant reduction (>80%), of the total OTA content was achieved, while in the subsequent phases (72–120h) OTA was slowly released into the grape juice by alginate beads. Biosorption properties of alginate-yeast beads were tested in a prototype bioreactor consisting in a glass chromatography column packed with beads, where juice amended with OTA was slowly flowed downstream. The adoption of an interconnected scaled-up bioreactor as an efficient and safe tool to remove traces of OTA from liquid matrices is discussed.This publication was made possible by NPRP grants # NPRP 4-259-2-083 and # NPRP 8-392-4- 003 from the Qatar National Research Fund (a member of Qatar Foundation)

Dose-effect study on the antioxidant properties of leaves and outer bracts of extracts obtained from <i>Violetto di Toscana</i> artichoke

Artichoke (Cynara scolymus L.) is an edible vegetable largely used in the Mediterranean diet and in folk medicine. The present paper discusses the analysis of the polyphenol content of leaves and outer bracts of Violetto di Toscana artichoke using different extraction procedures with the aim of establishing a correlation between polyphenol subclasses and antioxidant activity measured on human LDL oxidized by copper ions. HPLC/DAD and HPLC/MS analyses revealed that both the matrixes contain identical polyphenol subclasses, with mainly quantitative differences. The antioxidant effect of four artichoke extracts decreases in the following order when the sum of total phenolic compounds was considered: ethanolic extract from leaves (IC50 = 2.92 ± 0.46 μM); ethanolic extract from outer bracts (IC50 = 4.04 ± 0.21 μM); ethyl acetate extract from leaves (IC50 = 4.91 ± 0.11 μM); ethyl acetate extract from outer bracts (IC50 = 10.18 ± 1.6 μM). IC50 were also calculated considering the concentrations of single polyphenol subclasses. In both cases, the potency of antioxidant properties was not related to the amount of total polyphenols or the single subclasses