Chemical properties, fatty-acid composition, and antioxidant activity of Goji berry (Lycium barbarum l. and Lycium Chinense mill.) fruits

In this study, the content composition and antioxidant activity of goji berry fruits from two species (Lycium barbarum and Lycium chinense) were assessed. The total carbohydrate and phenolic contents were evaluated using attenuated total reflection Fourier-transform infrared (ATR-FT-IR) spectroscopy, while the antioxidant activity of fruits was examined with two in vitro methods, which are based on the scavenging activity of the 2,2-diphenyl-1-picrylhydrazyl (DPPH•) and 2,2’-azino-bis(3-ethyl-benzthiazoline-sulfonic acid) (ABTS•+) free radicals. The fatty-acid profile was determined using gas chromatography coupled with mass spectrometry (GC-MS). The results of this study indicate that the fruits of L. barbarum present higher concentrations in carbohydrates and phenolics than L. chinense Mill. fruits. Furthermore, the antioxidant activity based on the half maximal inhibitory concentration (IC50) measurements of DPPH• and ABTS•+ free-radical scavenging was higher in L. barbarum than L. chinense Mill. Also, the GCMS analysis confirms the high levels of linoleic, palmitic, and oleic acids contained in the fruits of both species. Finally, the results of this study clearly show that the concentration of bioactive and antioxidant molecules is higher in L. barbarum than in L. chinense fruits, which was also confirmed by ATR-FT-IR measurements. © 2019 by the authors. Licensee MDPI, Basel, Switzerland

The in vitro antimicrobial activity assessment of ultrasound assisted Lycium barbarum fruit extracts and pomegranate fruit peels

The present study aimed at assessing the antimicrobial properties of a water and ethanol ultrasound-assisted extraction (UAE) of dry goji berries and of lyophilised powdered pomegranate peel in vitro. Minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) methods, turbidity (cell density) measurement, and well diffusion assay were used to determine the antimicrobial activity against several species of foodborne bacteria (Gram – , Escherichia coli, Salmonella typhimurium, Campylobacter jejuni), (Gram + Staphylococcus aureus, Listeria monocytogenes, Clostridium perfringens), yeasts (Yarrowia lipolytica, Metschnikowia fructicola, and Rhodotorula mucilaginosa), and fungi (Penicillium expansum, Aspergillus niger, Fusarium oxysporum, and Rhizoctonia solani). Carbohydrate and phenolic contents were measured, and DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2΄-Azino-bis-(3-ethyl-benzthiazoline-sulphonic acid)) radical scavenging assays were used for the assessment of antioxidant activity. Fourier transform infrared (FTIR) spectrums of all samples were also evaluated in order to determine their chemical profiles. The lyophilised pomegranate peel exhibited the highest antioxidant, antimicrobial, and antifungal activity among all samples, while among the goji berry samples-who had only antibacterial and very little or no antifungal activity—the lyophilised aqueous extract with the lowest content of maltodextrin (2%) and highest phenolic content, had also the highest antioxidant, antimicrobial, and antifungal activity. The antioxidant and antimicrobial bioactivities seemed to be related to the content of polyphenols, the low concentration of maltodextrin in the encapsulated lyophilised samples and the use of optimised ultrasound assisted extraction. Minimum inhibitory concentration or zones of inhibition were in many (but not all) cases lower for the aqueous extracts compared to the ethanol or ethanol/hexane extracts of goji berries. In conclusion, the lyophilized powder of pomegranate peels and the aqueous extracts of goji berries encapsulated with minimal maltodextrin content and high polyphenol content exhibited high antioxidant and antimicrobial activity which could be utilized in food preservation or plant protection. © 2019, Springer Science+Business Media, LLC, part of Springer Nature