Investigating the effect of acoustic waves on spoilage fungal growth and shelf life of strawberry fruit.

The effects of acoustic waves on growth inhibition of food spoilage fungi (Aspergillus niger, Aspergillus flavus, Aspergillus parasiticus and Botrytis cinerea) on the medium and strawberry surfaces were investigated. Firstly, single-frequency sound waves (250, 500, 1000, 2000, 4000, 8000, 12,000 and 16,000 Hz) were induced on inoculated medium with fungi spores for 24 h and growth diameter of each mold was evaluated during the incubation period. In the second stage, the sound waves with two frequencies of 250 Hz and 16,000 Hz were induced on inoculated strawberries with fungi spores at 5 °C for different times (2, 4, 6, 8 and 10 days). The results from the first stage indicated that the sound waves inhibited the growth of A. niger (20.02%) at 250 Hz and B. cinerea (4/64%) at 4000 Hz on potato dextrose agar (PDA) surface. Also, comparison of the growth diameter of some species of Aspergillus revealed various responses in presence of 250 Hz frequency. In the second stage, applying a frequency of 250 Hz over a period of 10 days proved to be more effective in inhibiting the growth of A. niger and B. cinerea on strawberries inoculated with fungal spores. Consequently, the shelf lives of the strawberries significantly increased to 26 days and 18 days, respectively, under this treatment. Based on the findings, it is concluded that sounding with acoustic waves can be used as a green and cheap technology along with other technologies to improve food safety.

Ferula asafoetida: chemical composition, thermal behavior, antioxidant and antimicrobial activities of leaf and gum hydroalcoholic extracts.

This is the first original study on chemical, thermal, antimicrobial, and antioxidant activity of the leaf and gum hydroethanolic (20:80 v/v) extracts of Ferula asafoetida endemic for Iran. The ratio of solvent to the dried matters was 3:1 (w/w) and after filtering, the solvent was evaporated under vacuum (at 40 °C). Leaf extract contained greater phenolic and flavonoid compounds and thus higher DPPH scavenging and ferric reducing power. Leaf extract constituted high levels of carvacrol (15.40%) and α-bisabolol (9.75%) while in gum extract contained high levels of (Z)-b-ocimene (20.91%) and (E)-1-propenyl-sec-butyl-disulfide (17.62%). Umbelliprenin and ferulic acid were the major phenolic compounds in both extracts. Results of TGA and DSC revealed temperatures below and upper 100 °C and 160 °C as dominant regions of weight loss for gum and leaf extracts, respectively. Minimal inhibitory concentration for Escherichia coli, Staphylococcus aureus, Aspergillus niger, and Saccharomyces cerevisiae growth were 62.5, 62.5, 125, 125 mg/l and 400, 300, 50, 300 mg/l of leaf and gum extracts, respectively. Ferula asafoetida extracts can have particular applications in the food industry due to beneficial biological activity.

Quantification of crocin, picrocrocin and safranal in saffron stigmas obtained from sounded corms with acoustic waves.

INTRODUCTION: Plant acoustic frequency technology (PAFT) is the effect or treatment of a plant with a specific frequency sound wave. OBJECTIVE: The sound waves with different frequencies and a sound pressure level 77 dB were emitted on the saffron corms in a controlled environment using aeroponic cultivation and the contents of crocin, picrocrocin and safranal in their produced stigmas were analysed by high-performance liquid chromatography. For this purpose, the corms were divided into two groups. In group 1, sound waves with the frequencies of 0.5, 1 and 2 kHz were emitted on saffron corms in different stages of sprouting, flowering and the whole stage of sprouting and flowering. In group 2, sonication was performed on the corms during the flowering stage at 4, 8, 12 and 16 kHz frequencies. RESULTS: The changes in the contents of crocin, picrocrocin and safranal were not significantly compared to the control at 0.5, 1 and 2 kHz frequencies in the stages of sprouting and flowering of corms. While the higher frequencies (4, 8, 12 and 16 kHz) in flowering stage were affected significantly, the crocin and picrocrocin content increased 8.5% and 30%, applying the frequency of 12 and 8 kHz, respectively. Also, the effect of sound exposure time per day with the frequency of 16 kHz at 15, 30 and 60 min were investigated. CONCLUSION: The findings showed that the corms could be affected by sounding in the different stages of growth of the corm and also in the content of secondary metabolites.

Characterization of polyamide-6/ propolis blended electrospun fibers.

Polyamide-6 (PA-6) nanofibers and PA-6/propolis ethanolic extract (EEP) blended fibers were prepared having electrospun their solutions in formic acid as solvent. The effect of concentrations of PA-6 and also EEP in polymer solutions on the morphology and physicochemical characteristics of their electrospun fibers was investigated. The analysis of FESEM images showed the mean diameter of fibers increased from 487- 682 nm with increasing PA-6 concentration in the range of 25-40 % w/v. While, increasing EEP concentration (20-50% (w/w)) in PA-6/EEP system caused the increasing fiber mean diameters from 943- 1773 nm. Partially high aspect ratio nanofibers were observed only in the PA-6 systems. Antioxidant activity of the fibers enhanced with increasing EEP concentration in the fiber mats. FTIR spectrums and thermal properties of electrospun fibers exhibited the simple mixtures of PA-6 and EEP in blend fibers which did not contain very complex interactions.

Detection of chloramphenicol using a novel apta-sensing platform based on aptamer terminal-lock in milk samples.

In this paper, a novel apta-sensing colorimetric platform for rapid detection of chloramphenicol (CAP) in raw milk was developed. The AuNPs are stabilized by short-sequences aptamers against salt induced aggregation and this is the base of most colorimetric aptasensors development. However, the statute shows low sensitivity for the long-sequence aptamers. Herein, we propose an alternative strategy that use intact long-sequence aptamers for develop a highly sensitive AuNP-based colorimetric aptasensor. Determination of CAP in animal derived foods is an urgent demanded in the effort to minimize food safety risk. Therefore, we chose it as the representative model to construct the colorimetric sensing platform based on aptamer terminal-lock (ATL). In the ATL, intact aptamer was used as a molecular recognition element and a short-sequence oligonucleotide serving as a locker probe (LP) which is complementary of aptamer terminal fragments. By formation of aptamer/target complex, the LP leaves the ATL and adsorbs on the surface of AuNPs, leading to the AuNPs stabilization against salt-induced aggregation. This aptasensor shows a low limit of detection (0.03 nM) with high selectivity toward CAP. Moreover, the designed sensing platform was successfully applied to detect CAP in the milk samples. These results demonstrate our introduced label-free method for CAP detection is simple, sensitive, and highly selective.