Optimization of ultrasonic-assisted extraction of pomegranate (Punica granatum L.) peel antioxidants by response surface methodology

Standardization of the conditions for extraction of polyphenols from pomegranate peel

Pomegranate (Punica granatum) peel possess higher antioxidant activity than the edible portion. Efforts were made to extract dry peel powder at room temperature (28-30 °C) using combination of water and ethanol (EtOH, a green combination) and standardize the factors that may affect the extraction efficiency. The storage stability of the extract has been studied for >100 days at room temperature (28-30 °C), 4, 0 and -80 °C. The extract quality was monitored by measuring the radical scavenging activity (RSA) by diphenyl picrylhydrazyl (DPPH) method, total polyphenol content and by estimating the contents of punicalagins and ellagic acid, the two major ellagitannins present in the peel. The standardized conditions for extraction were found to be; Water and EtOH in 1:1 (v/v) ratio, duration of 24-48 h, ratio of 1:10 for solid to solvent and particle size in the range of 100-400 μ. Consecutive extraction of the peel powder did neither improve the yield nor polyphenol content, hence single extraction was adopted. The extract stored at room temperature for 110 days resulted in 13.2 % loss of polyphenol content followed by 8.9, 2.8, 27.5 and 14.1 % loss in Punicalgin A, B, Ellagic acid and RSA content, respectively.

Optimization of pulsed ultrasound-assisted technique for extraction of phenolics from pomegranate peel of Malas variety: Punicalagin and hydroxybenzoic acids

Pomegranate peel is a rich source of phenolic compounds (such as punicalagin and hydroxybenzoic acids). However, the content of such bioactive compounds in the peel extract can be affected by extraction type and condition. It was hypothesized that the optimization of a pulsed ultrasound-assisted extraction (PUAE) technique could result in the pomegranate peel extract with higher yield and antioxidant activity. The main goal was to optimize PUAE condition resulting in the highest yield and antioxidant activity as well as the highest contents of punicalagin and hydroxybenzoic acids. The operation at the intensity level of 105W/cm(2) and duty cycle of 50% for a short time (10min) had a high efficiency for extraction of phenolics from pomegranate peel. The application of such short extraction can save the energy and cost of the production. Punicalagin and ellagic acid were the most predominant phenolic compounds quantified in the pomegranate peel extract (PPE) from Malas variety. PPE contained a minor content of gallic acid.

Pomegranate peel and peel extracts: chemistry and food features

The present review focuses on the nutritional, functional and anti-infective properties of pomegranate (Punica granatum L.) peel (PoP) and peel extract (PoPx) and on their applications as food additives, functional food ingredients or biologically active components in nutraceutical preparations. Due to their well-known ethnomedical relevance and chemical features, the biomolecules available in PoP and PoPx have been proposed, for instance, as substitutes of synthetic food additives, as nutraceuticals and chemopreventive agents. However, because of their astringency and anti-nutritional properties, PoP and PoPx are not yet considered as ingredients of choice in food systems. Indeed, considering the prospects related to both their health promoting activity and chemical features, the nutritional and nutraceutical potential of PoP and PoPx seems to be still underestimated. The present review meticulously covers the wide range of actual and possible applications (food preservatives, stabilizers, supplements, prebiotics and quality enhancers) of PoP and PoPx components in various food products. Given the overall properties of PoP and PoPx, further investigations in toxicological and sensory aspects of PoP and PoPx should be encouraged to fully exploit the health promoting and technical/economic potential of these waste materials as food supplements.

Optimisation of ultrasonic-assisted extraction of phenolic compounds, antioxidants, and anthocyanins from sugar beet molasses

Response surface methodology was used to optimise experimental conditions for ultrasonic-assisted extraction (UAE) of functional components from sugar beet molasses. The central composite design (CCD) was used for the optimisation of extraction parameters in terms of total phenolic contents, antioxidant activities and anthocyanins. Result suggested the optimal conditions obtained by RSM for UAE from sugar beet molasses were as follows: HCl concentration 1.55-1.72 mol/L, ethanol concentration 57-63% (v/v), extraction temperature 41-48 °C, and extraction time 66-73 min. In the optimal conditions, the experimental total phenolic contents were 17.36 mg GAE/100mL, antioxidant activity was 16.66 mg TE/g, and total anthocyanins were 31.81 mg/100g of the sugar beet molasses extract, which were well matched the predicted values. Teen compounds, i.e. gallic acid, vanillin, hydroxybenzoic acid, syringic acid, cyanidin-3-O-rutinoside, cyanidin-3-O-glucoside, catechin, delphinidin-3-O-rutinoside, delphinidin-3-O-glucuronide and ferulic acid were determined by HPLC-DAD-MS/MS in sugar beet molasses.