Storage In Different Conditions Research Articles

Kinetic study on unsaponifiable fraction changes and lactose hydrolysis during storage of Mozzarella di Bufala Campana PDO cheese

Cholesterol, vitamin E and vitamin A isomers, components of the unsaponifiable fraction, and lactose contents in Mozzarella di Bufala Campana PDO cheese have been studied during storage in different conditions: at 6–8°C, and at room temperature (traditional habits). During cold storage there were no significant differences in the unsaponifiable compounds, while during storage at room temperature an increase of the 13-cis isomer and a decrease of all-trans-retinol were observed. Trans/cis-retinol isomerization, expressed as the Degree of Retinol Isomerization (13-cis/all-trans%) showed an increase in all samples during storage at room temperature following a linear correlation. The decrease of lactose content during storage was studied by a first-order differential relaxation equation. Apart from the traditional habits, consumers should be aware that, during storage at room temperature, the most important changes in the considered nutrients occur. These changes can be negative (vitamin A reduction) but also positive (lactose reduction).

Hop pellets type 90: Influence of manufacture and storage on losses of α-acids

Hop pellets type 90 are the most frequent hop products used in brewing. They are usually manufactured by drying hop cones, temporary storage of dry and pressed cones, milling and pelletising. Other possibility is a complete integration of hop harvest, cone drying, milling and pelletising in continuous process without temporary storage of pressed cones. The paper deals with the losses of bitter substances (primary α-acids) during hop cones drying, their pelletisation by two manufacturing procedures and storage in different conditions. The results of this study show that integrated procedure of hop pelletising decreases the total loss of α-acids compared to the usual procedure. During storage of hop pellets (produced by integrated procedure) the highest decrease (loss) of α-acids content was observed in pellets stored at 21 °C in the presence of air and the lowest under inert atmosphere (N 2 ) at 4 to 7 °C, respectively.

Fluorescence spectroscopy in monitoring of extra virgin olive oil during storage

SummaryThe present study demonstrates the use of fluorescence spectroscopy for monitoring changes in virgin olive oil during storage. Total luminescence and synchronous scanning fluorescence spectroscopy techniques were tested with the purpose to check their ability to monitor changes occurring in olive oil during storage in different conditions: in clear and green glass bottles exposed to light, and in darkness. Total luminescence spectra of the initial oil samples in n‐hexane solutions exhibited intense peaks, one with a maximum appearing at 320 nm in emission and 290 nm in excitation, attributed to tocopherols, and another appearing at 670 nm in emission and 405 nm in excitation, belonging to the pigments of the chlorophyll group. The intensity of these emissions decreased during storage depending on the storage conditions. Additional bands appeared in oils exposed to light in the intermediate range of excitation and emission wavelengths, arising from unidentified compounds. Bands attributed to tocopherols, chlorophylls and those tentatively ascribed to phenolic compounds were observed in the synchronous scanning fluorescence spectra, allowing monitoring of the storage effects on these constituents and their quantitative assessment after appropriate calibration. The results presented confirm the capability of the fluorescence techniques to monitor the quality of oil products.

Use of microwave in chicken breast and application of different storage conditions: consequences on oxidation

Slices of chicken breast were subjected to microwave heating (750 W, 3 min) and further storage in different conditions (refrigeration at 4 °C and freezing at −18 °C combined with aerobic, vacuum, and modified atmosphere packaging). Evaluation of the intensity of the oxidation process was carried out. A 16-fold increment in the amount of cholesterol oxidation products (COP) was found as a consequence of microwave cooking (45.86 μg/g lipid after microwave and 2.88 μg/g lipid in raw samples). 7-ketocholesterol was the most affected COP by microwave, accounting for a 25% of the total COP. Storage of microwaved samples under aerobic refrigeration led to the highest oxidation status with the following values: peroxide 19.41 meqO2/kg lipid, TBA 0.32 ppm and COP 123.50 μg/g lipid. MAP refrigerated samples showed 50.94 μg/g lipid of total COP, an amount slightly higher than in vacuum conditions (46.81 μg/g lipid). Under frozen storage MAP and vacuum samples showed the lowest amounts of total COP (29.76 and 39.28 μg/g lipid, respectively).

Changes in Insoluble and Soluble Dietary Fiber of White Asparagus (Asparagus officinalis L.) during Different Conditions of Storage

Changes occurring in the content and composition of dietary fiber of white asparagus during storage in different conditions were studied (room temperature; 2 °C in polyethylene bags; 2 °C and 95% relative humidity). The neutral sugars and uronic acid composition of dietary fiber was determined by gas chromatography and by a spectrophotometric method. In the insoluble dietary fiber, glucose was found in a major amount followed by galactose, xylose, arabinose, mannose, rhamnose, and fucose. In the soluble dietary fiber, galactose was the predominant neutral sugar followed by arabinose, mannose, glucose, and rhamnose. The content of uronic acids was significantly higher in the soluble dietary fiber than in the insoluble one. The modifications observed in dietary fiber of the asparagus stored at room temperature are more rapid and pronounced than those in the refrigerated conditions, which prolong the conservation. Statistical analysis indicated that the changes were significantly affected by the type of storage and time. Keywords: Dietary fiber; asparagus; changes; storage

Bacteriocin Production by Lactic Acid Bacteria Isolated from Regional Cheeses: Inhibition of Foodborne Pathogens

Four strains of enterococci isolated from Argentina regional cheeses were found to produce bacteriocins that were active against several lactic acid bacteria. Among them, enterocin CRL35 produced by Enterococcus faecium CRL35 was also inhibitory to foodborne pathogens like Listeria monocytogenes and Staphylococcus aureus. These antimicrobial compounds were sensitive to proteases and heat stable; inhibitory activity of enterocin CRL35 showed also to be stable at extreme pHs, heat treatment, and storage in different conditions.

Effect of serum pH on bilirubin-protein binding.

Progressive increase of the serum pH upon standing and storage in different conditions is documented. Bilirubin albumin titration studies were performed on serum of different pH by Sephadex gel filtration and horseradish peroxidase oxidation methods. Results showed that different pH produced different titration curves and that more reproducible and consistent results were obtained with the peroxidase oxidation titration method. Addition of HCl and CO2 to the serum also produced different bilirubin-protein titration results. For bilirubin albumin binding studies, we suggest to adjust the pH to 7.4 with CO2 to obtain clinically meaningful data.

Endogone Spores in a Heathland Area of South-Eastern Australia

An area of heath occurring on sandy podzolic soil at Cranbourne in Victoria has been studied. Relative spore numbers of vesicular-arbuscular mycorrhizal fungi have been monitored over a period of 2 years at sites containing disturbed and undisturbed native vegetation, as well as recolonizing areas of mixed indigenous and introduced species. A large number of 'Endogone' spores were found, and some correlation between peak spore numbers and periods of high rainfall was recorded at the disturbed sites. No such correlation was found in undisturbed heath. Many spores of varying morphology were examined, and eight spore types belonging to the non-sporocarpic members of the Endogonaceae have been described in detail. The viability of a white, bulbous-based spore type was investigated following storage in different conditions for varying lengths of time.