Microbial diversity and dynamics of Pecorino di Filiano PDO,a traditional cheese of Basilicata region (Southern Italy)

The evolution of microbial populations of ‘Pecorino di Filiano’ (PF) cheese was investigated during ripening in natural cave and storeroom. 62.5% of isolates grow at 45 and 15 °C and 77.7% showed high salt concentrations tolerance. Brevibacterium linens was dominant in surface samples. Lactobacillus delbrueckii subsp. bulgaricus and Lactobacillus paracasei subsp. paracasei were more frequently isolated both surface and core samples, while Leuconostoc lactis and Leuconostoc mesenteroides subsp. mesenteroides prevailed among Leuconostoc isolates. Our results suggest the importance of the ripening environment of cheeses and how a biological ecosystem affects and produces the typical features of artisanal products.     

RHEOLOGY OF SUCROSE-CMC MODEL SOLUTION

The rheological behavior of an aqueous solution composed of 65% sucrose and 0.1% CMC was experimentally determined from -10C to 50C using a rotational viscometer equipped with coaxial cylinders. The model solution behaved as pseudoplastic fluid, represented by the power-law model. Flow behavior and consistency indices determined at -10.1, 0.5, 9.8, 19.0, 30.1 and 50. OC, showed values between 0.79 to 0.86 and 0.15 to 10.22 Pa. sⁿ, respectively. The effect of temperature on the rheological parameters was represented by Arrhenius-type relationships, with R²≥ 0.97. They were compared to the rheological behavior of a concentrated orange juice with 65° Brix and 7% pulp content. The comparison of separate rheograms for both fluids showed that the model solution can be used to represent concentrated orange juice.     

STARCH MOBILIZATION AND SUCROSE ACCUMULATION IN THE PULP OF KEITT MANGOES DURING POSTHARVEST RIPENING

Sugar is a determinant for the quality of mangoes, but information about its accumulation is scarce. Although starch can contribute to sugar production during ripening, not much is known about the enzymes involved. This work presents the changes in carbohydrate and enzymes during the development and ripening of Keitt mangoes. Starch disappearance was concomitant to a fivefold increase of sucrose, the most abundant sugar of the ripe fruits. The activities of α-amylase, β-amylase, phosphorylase and isoamylase were detected in the pulp, and while α-amylase increased parallel to the starch content, β-amylase presented a 20-fold increase during ripening. On the other hand, high phosphorylase activity was observed when fruits were still accumulating starch, and lowered during ripening. Isoamylase was detected during development and increased slightly during ripening, which would be in agreement to the expected role for isoamylases as acting on both subproduct of starch synthesis and degradation.

PRACTICAL APPLICATIONS

The present work reinforces our previous works that Keitt mangoes do not ripen when attached to the tree. This fact allowed us to study all the starch degradation after mango harvesting which does not occur with the other cultivars. Data obtained in this work reinforce the role of α-amylase, β-amylase and isoamylase rather than the starch phosphorylases on starch granule degradation in mangoes, and the subsequent soluble sugar accumulation.     

CHEMICAL CHARACTERIZATION AND PREPARATION OF SALTED MINCES FROM BIGEYE GRUNT AND LONGFIN BONEFISH

The proximate chemical composition, amino add and fatty add profile of bigeye grunt (Brachydeuterus auritus) and longfin bonefish (Pterothrissus belloci) minces were determined. Both minces contained a low fat content. Polyunsatu‐rated fatty adds represented more than 50% of the fatty adds in bigeye grunt but in the case of longfin bonefish the percentages of saturated, mono‐, and polyunsaturated were similar. The amino add profile of minces from these species was very similar. The preparation of salted minces using different drying methods is described. The chemical and physical characteristics of raw and dried salted minces as well as cooked products were measured. Dried salted minces from these species had high water uptake and cooked products presented a low salt content (1 %). Cooked rehydrated salted minces from longfin bonefish were lighter in color than those from bigeye grunt and color values were not significantly influenced by the salt level used in the preparation.     

Cholesterol Oxidation in Baked Foods Containing Fresh and Powdered Eggs

The degree of cholesterol oxidation in commercial sweet baked foods (biscuits and snacks) and in laboratory baked biscuits, all containing fresh or powdered eggs, was determined. 7-Ketocholesterol was used as index of cholesterol oxidation and detected by two analytical methods. The analysis of the biscuits showed higher levels of 7-ketocholesterol and a more marked oxidative instability of cholesterol when prepared with powdered eggs. The significant amounts of 7-ketocholesterol found in some samples of commercial biscuits were attributed to the use of powdered eggs. These data are of importance to industries using eggs in sweet baked products which are mainly consumed by children.     

Effect of Phytic Acid on the In-Vitro Rate of Digestibility of Rapeseed Protein and Amino Acids

Phytic acid in rapeseed flour was reduced by pH adjustment to 5.15 with subsequent dialysis or by phytase treatment at pH 5.15 with subsequent dialysis. The effect of phytate reduction on the rate and extent of protein and amino acid digestibilities was then determined using an in vitro pepsin-pancreatin proteolysis method with simultaneous dialysis of reaction products. A 51% reduction in phytic acid increased the rate of release of many essential amino acids but a further 89% reduction in phytic acid did not enhance that effect. Phytate removal did not improve the protein digestibility.     

Metastability of Tetragonal Zirconia Powders

The formation of metastable t -ZrO₂ by thermal treatment was studied in a systematic way on two different samples: a gel (G) and zirconyl acetate (A). The results show that initially nucle-ation of t -ZrO₂ is favored by creation of anionic vacancies with trapped electrons. At higher temperatures the electronic defects disappear, the crystallites grow, and the m -phase can nucleate. This evolution is observed perfectly on sample A because of its special morphological characteristics.     

EFFECT OF FISH PROTEIN PREPARATIONS ON RHEOLOGICAL PROPERTIES OF MEAT SAUSAGES

The properties of sausage emulsions, containing up to 30% fish proteins in respect to total N × 6.25, were characterized by viscosity and water holding capacity and after heating by yield, quantity of expressible fluid, water holding capacity, yield limit, creep curve, and sensory quality. Substitution of 15% meat protein by fish protein does not decrease the sausage yield nor impair the rheological properties of the formulation or of the cooked product. Sensory differences were detectable between the controls and sausages containing up to 10% of fish isolate or 20% concentrate.