Hazelnut Shells as Source of Active Ingredients: Extracts Preparation and Characterization

Abstract

Hazelnut shells represent a waste material (about 42% of the total biomass) deriving from hazelnut harvest. These are mainly used as a heating source; however, they represent an interesting source of polyphenols useful in health field. The impact on phenolic profile and concentrations of hazelnut shell extracts obtained by three extraction methods (maceration, ultrasonic bath, and high-power ultrasonic), as well as temperature, extraction time, and preventive maceration, was studied. The prepared extracts were characterized in terms of chemical composition, antioxidant and antimicrobial activities. Eighteen different phenolic compounds were identified and quantified by chemical analysis and gallic acid was the most abundant in all the extracts analyzed. Other relevant compounds were chlorogenic acid, protocatechuic acid and catechin. Preventive maceration had a positive effect on the extraction of different types of compounds regardless of the method performed. Application of the high-power ultrasonic method had different effects, either positive or negative, depending on the type of compound and extraction time. All the prepared extracts showed antioxidant activity especially those prepared by maceration, and many of them were able to inhibit the growth of both B. subtilis and B. cereus.

Effect of the Application of a Green Preservative Strategy on Minced Meat Products: Antimicrobial Efficacy of Olive Mill Wastewater Polyphenolic Extract in Improving Beef Burger Shelf-Life

“…The evaluation of the antimicrobial activity of CM and PE extract was performed through the agar well diffusion technique [ 31 , 32 ] on some micro-organisms relevant for the food industry, such as Staphylococcus aureus (WDCM 00034), Escherichia coli (WDCM 00013) and Pseudomonas fluorescens (WDCM 00115). The selected reference strains were revitalized in Brain Heart Infusion (BHI) broth and incubated at 37 °C for 24 h with the exception of P. fluorescens , which was incubated at 25 °C for 24–48 h. An initial suspension of 0.5 McFarland in 0.9% sterile saline solution was prepared for each micro-organism, and 100 µL was then distributed on Mueller–Hinton Agar (MHA, Thermo Fisher Scientific, Milan, Italy) plates with a swab, making four 90° rotations.…”

“…At the time of use, the extracts were suspended with sterile demineralized water to obtain a concentration of 750 mg/mL, and then two dilutions were performed at 375 and 187 mg/mL. In each inoculated MHA plate, 7 mm-diameter holes were produced with a sterilized cork borer and then filled with 50 µL of extract suspension at different concentrations [ 31 , 32 ]. The plates were incubated according to the most suitable growth conditions, as reported above.…”

Crocus sativus L. Petal Extract Inhibits Inflammation and Osteoclastogenesis in RAW 264.7 Cell Model

“…Total duration of the analysis was of 12 min. Compounds' identifications were performed through a QTRAP 4500 tandem mass spectrometer (Sciex, Concord, ON, Canada), coupled with an electrospray ionization source (V-source) operating in negative ionization mode as previously described [25].…”

Circular Hazelnut Protection by Lignocellulosic Waste Valorization for Nanopesticides Development

“…The chemical composition of shoots (taken as a hardwood) and shells are as follows, respectively: 40-55% and 25-30% cellulose, 25-40% and 25-30% hemicellulose and 15-25% and 30-40% lignin, representing an attractive source of organic compounds of interest [31,32]. Indeed, these lignocellulosic residues can be valorized through the extraction of organic fractions, such as polyphenols and other secondary metabolites, and converted into high value-added compounds, following the circular economy concept [33][34][35]. Cellulose and lignin can be extracted too and further converted in their nanoscale form, exhibiting many more exploitable features with respect to their bulk counterpart [36].…”