Characterization of prickly pear juice by means of shelf life, sensory notes, physicochemical parameters and bio-functional properties.

ABSTRACT: The objective of the present work was to characterize prickly pear juice prepared from prickly pear fruits of the wild cultivar in terms of shelf life (air and vacuum packaging), sensory stability (odour, taste, and appearance) physicochemical parameters (acidity, vitamin C, pH, electrical conductivity, total dissolved solids, specific weight, total sugar content, and colour coordinates L*, a*, b*) and bio-functional properties [in vitro antioxidant activity (AA%) and total phenolic content (TPC)]. For this purpose fruits were collected during August 2017 from 3 different geographical zones in Peloponnese. The shelf life of prickly juice was extended by 5 days in vacuum compared to air packaging, whereas it was found to be a rich source of phytochemicals and a natural antioxidant agent (AA of 67.33 ± 5.89-75.63 ± 4.41% and TPC of 3234.5 ± 978.2-7592.1 ± 2441.0 mg GAE L-1), in relation to fruit geographical origin (P < 0.05). The exploitation of prickly pear juice is really a challenge.

Physico-Chemical Parameters, Phenolic Profile, In Vitro Antioxidant Activity and Volatile Compounds of Ladastacho (Lavandula stoechas) from the Region of Saidona.

The aim of the present study was to characterize Lavandula stoechas (Ladastacho) from the region of Saidona by means of physico-chemical parameters, phenolic profile, in vitro antioxidant activity and volatile compounds. Physico-chemical parameters (pH, acidity, salinity, total dissolved solids, electrical conductivity and liquid resistivity) were determined using conventional methods. The phenolic profile was determined using high-performance liquid chromatography electrospray ionization mass spectrometry (HPLC/ESI-MS), whereas a quantitative determination was also accomplished using the total phenolics assay. In vitro antioxidant activity was determined using the 2,2-diphenyl-1-picryl-hydrazyl assay. Finally, volatile compounds were determined using headspace solid phase microextraction coupled to gas chromatography mass spectrometry (HS-SPME/GC-MS). The results showed that Lavandula stoechas aqueous extract had a slightly acidic pH, low salinity content and considerable electrochemical properties (electrical conductivity and liquid resistivity along with electric potential). In addition, aqueous fractions showed a significantly (p < 0.05) higher phenolic content and in vitro antioxidant activity, whereas phenolic compounds, such as caffeic acid, quercetin-O-glucoside, lutelin-O-glucuronide and rosmarinic acid, were identified. Finally, numerous volatile compounds were found to dominate the volatile pattern of this flowering plant, producing a strong, penetrating, cool and menthol-like odour.

Combined effect of ozonation and packaging on shelf life extension of fresh chicken legs during storage under refrigeration.

The aim of the present study was to investigate the effect of different ozone doses (2, 5, and 10 mg/L) on shelf life extension of fresh chicken legs, packaged in polyamide/poleyethylene bags and stored at 4 ± 1 °C, for a period of 12 days. Parameters taken into account were: microbiological (Total viable count, Pseudomonas spp., Lactic acid bacteria, Yeasts and molds, and Enterobacteriaceae), physicochemical (pH, colour) and sensory (odor, appearance, texture, and taste) attributes. Results showed that colour parameter values (L*, a*, and b*) were not affected by the gaseous ozone dose, whereas only L* and b* were reduced during storage in all samples. pH was reduced by storage time but was not affected by ozonation dose and packaging. Total viable count and Pseudomonas spp., increased statistically significant with ozonation dose and storage time, but were not affected by packaging. Yeasts, molds, Enterobacteriaceae, and Lactic acid bacteria, were decreased during storage, packaging and ozonation dose. Finally, sensory examination (appearance, texture, odor and taste) showed that samples treated with ozone concentration of 10 mg/L retained the original characteristic features of fresh chicken legs as compared to the control samples. The gaseous ozone treatment of 10 mg/L for 1 h, to chicken legs packaged in plastic containers of polyamide/polyethylene under refrigeration, is appropriate for maintaining freshness and quality of chicken, since their shelf life was extended by 4 days, as compared to the control samples.

Effect of irradiation, active and modified atmosphere packaging, container oxygen barrier and storage conditions on the physicochemical and sensory properties of raw unpeeled almond kernels (Prunus dulcis).

BACKGROUND: The present study investigated the effect of irradiation, active and modified atmosphere packaging, and storage conditions on quality retention of raw, whole, unpeeled almonds. Almond kernels were packaged in barrier and high-barrier pouches, under N(2) or with an O(2) absorber and stored either under fluorescent lighting or in the dark at 20 °C for 12 months. Quality parameters monitored were peroxide value, hexanal content, colour, fatty acid composition and volatile compounds. Of the sensory attributes colour, texture, odour and taste were evaluated. RESULTS: Peroxide value and hexanal increased with dose of irradiation and storage time. Irradiation resulted in a decrease of polyunsaturated and monounsaturated fatty acids during storage with a parallel increase of saturated fatty acids. Volatile compounds were not affected by irradiation but increased with storage time indicating enhanced lipid oxidation. Colour parameters of samples remained unaffected immediately after irradiation. For samples packaged under a N(2) , atmosphere L and b values decreased during storage with a parallel increase of value a resulting to gradual product darkening especially in irradiated samples. CONCLUSION: Non-irradiated almonds retained acceptable quality for ca. 12 months stored at 20 °C with the O(2) absorber irrespective of lighting conditions and packaging material oxygen barrier. The respective shelf life for samples irradiated at 1.0 kGy was 12 months packaged in PET-SiOx//LDPE irrespective of lighting conditions and 12 months for samples irradiated at 3 kGy packaged in PET-SiOx//LDPE stored in the dark.

Determination of diethylhexyladipate and acetyltributylcitrate in aqueous extracts after cloud point extraction coupled with microwave assisted back extraction and gas chromatographic separation.

The determination of commercial plasticizers (di-(2-ethylhexyl)adipate (DEHA) and acetyl tributyl citrate (ATBC)) in aqueous solutions is described. The newly proposed technique of applying microwaves to cloud point extracts in order to enable combination with gas chromatographic analysis has been used for this purpose. Both plasticizers were entrapped in the micelles of the non-ionic surfactant Triton X-114 and removed from the bulk phase by centrifugation. Micellization was enhanced by increasing the ionic strength of the solution with concentrated NaCl. Extraction recoveries of the proposed method were over 95% for water and 3% (w/v) aqueous acetic acid and over 85% for 10% (v/v) aqueous ethanol, respectively. The calibration curves obtained, following the proposed methodology have a linear range between 50 and 2000 microg/L for each analyte while the detection limits were as low as 15 and 19 microg/L for DEHA and ATBC, respectively, with an RSD below 5% even for low concentrations. As an analytical demonstration the proposed methodology was applied for the determination of the migration levels of the selected plasticizers from a PVC food packaging film into aqueous simulants.

Control of natural microbial flora and Listeria monocytogenes in vacuum-packaged trout at 4 and 10 degrees C using irradiation.

The effect of gamma irradiation on the natural microflora of whole salted vacuum-packaged trout at 4 and 10 degrees C was studied. In addition, the effectiveness of gamma irradiation in controlling Listeria monocytogenes inoculated into trout was investigated. Irradiation at doses of 0.5 and 2 kGy affected populations of bacteria, namely, Pseudomonas spp., Brochothrix thermosfacta, lactic acid bacteria, H2S-producing bacteria typical of Shewanella putrefaciens, and Enterobacteriaceae, at both 4 and 10 degrees C. This effect was more pronounced at the higher dose (2 kGy) and the lower temperature (4 degrees C). Pseudomonads, H2S-producing bacteria typical of S. putrefaciens, and Enterobacteriaceae showed higher sensitivity to gamma irradiation than did the rest of the microbial species. Sensory evaluation did not show a good correlation with bacterial populations. On the basis of sensory odor scores, a shelf life of 28 days (2 kGy, 4 degrees C) was obtained for salted vacuum-packaged freshwater trout, compared with a shelf life of 7 days for the unirradiated sample. Under the same conditions, the growth of L. monocytogenes inoculated into the samples was suppressed by 2 log cycles after irradiation (2 kGy) and storage for up to 18 days at 4 degrees C.