Journal of Food Quality and Hazards Control
Volume:8 Issue: 1, Mar 2021

Freezing is a common and ancient method for preservation of foods which is applicable both under household and industrial conditions. The objective of the study was to establish histological and microbiological changes in dorsal and abdominal muscles of rainbow trout (Oncorhynchus mykiss) after freezing once and twice.

Forty-five fresh rainbow trout specimens were distributed into three groups of 15 fish each. The first group was subjected to histological and microbiological analysis immediately after delivery at the laboratory. The second fish group was frozen at -18 °C for 15 days, while the third group of fish was frozen at -18 °C for 15 days, thawed and frozen again at -18 °C for 15 days. Data were analyzed using GraphPad InStat 3 software.

After freezing once, muscle fibers with intracellular void spaces were observed and retained stable peripheral boundary. In some muscle fibers, the endomysium boundaries were visible and with retained integrity. After freezing twice, damages and deformities were observed resulting in completely destructured muscle fibers. Large void spaces among the muscle fibers and bundles were greatly the result of shrinking and grouping of fibers and the laceration of endomysium and perimysium internum. Total microbial count and Enterobacteriaceae count had no significant differences (p>0.05) between fresh, frozen once, and frozen twice trout.

Muscles of rainbow trout (O. mykiss) are histologically damaged to a greater extent after freezing twice and thawing. However, microbiological indicators had no change significantly after freezing once and twice.

Tuber aestivum Vittad., known as black summer truffle, represents high-value food especially used as garnishment in nouvelle cuisine. The aim of this study was to investigate on the viable microbial populations associated with T. aestivum ascomata collected in different sites of Sicily and one locality of Umbria (Italy).

The ripe ascomata of black summer truffles were collected from Central Italy. Cell densities of spoilage bacteria, fecal indicators, potential pathogens, yeasts, and molds were analyzed. Statistical analysis was conducted with XLSTAT software.

The microbiological counts of truffles ranged between 6.00 and 9.63 log Colony Forming Unit (CFU)/g for total mesophilic count and between 6.18 and 8.55 log CFU/g for total psychrotrophic count; pseudomonads were in the range 6.98-9.28 log CFU/g. Listeria spp. and coagulase-positive streptococci detected in no samples. Coagulase-negative streptococci were found in some samples with 2.11-4.76 log CFU/g levels. Yeasts and filamentous fungi were detected at consistent levels of 3.60-7.81 log CFU/g. Significant differences (p<0.01) were found between samples and also for all microbial groups.

This study evidenced that the common brushing procedure applied for preparation of truffles is not sufficient to eliminate microbial risks for consumers. The application of an efficient decontamination treatment is strongly suggested before consumption of fresh truffles.

Drying is the one of the oldest methods for increasing the shelf life of food products. The objective of the present study was evaluation of effect of different drying temperatures on drying time and storage quality parameters of in-shell hazelnut.

Hazelnuts were dried as a thin layer at three temperatures (40, 50, and 60 °C). The time required for drying and quality parameters (lipid and protein content, acidity, and peroxide value) were evaluated. Besides, sensory and oxidation evaluations were performed in order to evaluate the effect of the drying temperatures on quality of hazelnuts before and after 6-month storage. Data were analyzed by SPSS software (V. 16.0).

The mean drying times at 40, 50, and 60 °C were 29.75, 25, and 20.25 h, respectively. In fact, an inverse significant (p<0.05) relationship was observed between temperature and time of the hazelnuts drying process. The mean protein content of the hazelnuts dried at 40, 50, and 60 °C were 13.06, 12.83, and 13.62 (% dry basis), respectively. Lipid content of the samples were significantly (p<0.05) increased with drying temperature. The lowest acidity and peroxide values were recorded for the samples dried at 60 °C with the values of 0.15% oleic acid and 1.3 meq/kg, respectively. Sensory results showed that all of the treated hazelnuts were acceptable after six months storage.

The evidences of the present study point that in-shell hazelnuts drying at temperature of 60 °C can lead to production of good quality products.

Sodium caseinate is a rich source of protein and minerals originating from animals. Numerous food and non-food products are made from sodium caseinate. The present study investigated the chemical components (moisture, crude protein, ash, and soluble crude protein) of sodium caseinate prepared by different acids and drying techniques.

A completely randomized factorial design was used by different acids including hydrochloric acid (HCl) and acetic acid, and also drying methods including oven (50 °C for 48 h) and freeze drying (-40 °C for 48 h). In each experimental group, sodium caseinate was obtained for determination of moisture, crude protein, ash, and soluble crude protein. Data were statistically evaluated using an ANOVA in SPSS 18.0.

The interaction of both acids and drying methods significantly (p<0.01) affected moisture, crud protein, and ash content. HCl treatment coupled with freeze drying was the best combination, resulting in an appreciably higher content of crude protein (52.90%), moisture (5.38%), and soluble protein (0.85%).

The kinds of acid and drying method altered the chemically profile of sodium caseinate. The combination of HCl and freeze drying could be the considered as the best approach, resulting in good chemical characteristics of sodium caseinate.

Essential Oils (EOs) are natural metabolic products of plants that contain a condensed chemical hydrophobic liquid compounds. The aim of this study was to evaluate inhibitory effects of EOs of Cinnamon zeylanicum and Myristica fragrans against Brucella abortus 544 inoculated in fresh Baladi cheese.

Fresh Baladi cheese was manufactured from experimentally contaminated milk with B. abortus 544 in combination of EOs of C. zeylanicum or M. fragrans. Cheese samples were periodically subjected to further microbiological surveys at different storage times (0, 1, 24, 48, 72, and 96 h). The inhibition zone diameter and Minimum Inhibitory Concentration (MIC) against tested strain were also determined. Statistical analyses were conducted by GraphPad Prism Statistical Software.

The inhibition zone diameter of the paper disk were 9.5±0.5 and 16±0.57 mm at 1% concentration of M. fragrans and C. zeylanicum EOs, respectively; and 15±0.28 and 21±0.76 mm at 5% concentration of M. fragrans and C. zeylanicum EOs, respectively. The values of inhibition zone diameters were significantly (p<0.0001) different between the two selected concentrations of 1% and 5% for the studied EOs. Also, anti-Brucella activity of C. zeylanicum was significantly (p<0.0001) more than that of M. fragrans EO.

Due to the appropriate anti-Brucella activity, C. zeylanicum EO could be applied as an effective natural preservative in the production of fresh Baladi cheese. Conversely, using M. fragrans EO could not protect the fresh Baladi cheese against Brucella.

Among important fungi associated with foods are Aspergillus spp., Penicillium spp., and Geotrichum spp. In this study, we evaluated antifungal effects of Essential Oils (EOs) of Zataria multiflora, Mentha pulegium, and Mentha piperita.  

Antifungal properties of EOs of M. piperita, M. pulegium, and Z. multiflora against Aspergillus spp., Penicillium spp., and Geotrichum candidum were determined by agar well diffusion and broth macrodilution method. Data were analyzed by SPSS 20.

Among three studied plant EOs, Z. multiflora EO had the strongest antifungal activity (p<0.05) on tested fungi; so that the Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC) were 0.01 and 0.3% for G. candidum, 0.005 and 0.3% for Penicillium spp., and 0.1 and 0.3% for Aspergillus spp.

All three studied plant EOs showed antifungal activities. However, as Z. multiflora EO showed the most antifungal effect, it could be specially suggested as natural powerful antifungal preservatives in the food industry.

Zataria multiflora Boiss. (Avishan-e Shirazi), as an Iranian endemic plant, belongs to the Lamiaceae family and may be used as a food preservative. This study aimed to detect potential genotoxic effects of Z. multiflora extract. 

Hydro-alcoholic extract of Z. multiflora was prepared. Human B lymphocytes were treated with 1% extract within 3 and 24 h. Sterile Phosphate Buffered Saline (PBS) and cisplatin were used as negative and positive controls, respectively. DNA damage profiles were examined using comet assay (Single Cell Gel Electrophoresis). Data were statistically analyzed by SPSS software v. 21.

No statistically significant (p=0.071) DNA damage was observed in B lymphocytes treated with either Z. multiflora extract or PBS after 3 and 24 h. However, there was a statistically significant difference (p=0.0001) between DNA damage in B lymphocytes that treated with cisplatin and Z. multiflora after 3 and 24 h.

The comet assay used in the current study showed that Z. multiflora had no genotoxic effect.