Incorporation of defatted apple seeds in chewing gum system and phloridzin dissolution kinetics

Highlights

• Defatted apple seeds demonstrated significant antioxidant activity.

• Phloridzin was a characteristic phenolic compound of defatted apple seeds.

• Chewing gum could be a suitable material for phloridzin uptake.

• 5 min chewing was enough for the dissolution of almost all phloridzin.

• Novel model was developed to describe dissolution kinetics.

Abstract

Apple seeds are among the major natural sources of antioxidants and can be used in various industries. In this regard, antioxidant activity, total phenolic content, and individual phenolic compounds analyzes of defatted apple seed flours were firstly done in our study. According to these analyzes, total phenolic content, DPPH and ABTS radical scavenging activity of defatted seed flours were determined between 2861 and 5141 mg GAE/kg defatted seed, 21.45–43.56 μmol, and 291.50–391.79 μmol Trolox/g defatted seed, respectively. It was observed that the content of phloridzin represented 52–67% and 75–83% of the total phenolics that measured by the Folin-Ciocalteu assay and HPLC method, respectively. In the second part, chewing gums including defatted seeds were prepared and characterized in terms of phloridzin dissolution. The novel model described dissolution kinetics of phloridzin from chewing gum better than Higuchi and Korsmeyer-Peppas models. The results demonstrated that 5 min was enough for the dissolution of almost all phloridzin (88.43–96%) determined by centrifugation method and according to the model parameters, the chewing gum formulation can be optimized for providing controlled dissolution. In conclusion, chewing gum could be a suitable delivering material for phloridzin uptake, and apple seeds, a valuable agricultural by-product, could be evaluated in this way.

Introduction

The increase in the production of apples in parallel with the world population and the widespread consumption of apples and its derivative products have increased the amount of by-products that are released after processing. In this respect, two branches of the industry that produce large amounts of apple by-products are the juice and fresh-cut fruit salad production (Górnaś, 2015). For instance, the apple pomace (press cake) obtained during juice pressing represents approximately 20–35% of the initial amount of fruits, and the composition of pomace consists of 94.5% flesh and skin, 4.1% seeds and 1.1% fruit stems (Candrawinata et al., 2015). Therefore, the scientific studies were not only confined to fruit juices, flesh, and peels but also were carried out on apple seeds.

Recently, it has been determined that the apple seeds are a rich source of polyphenols and show significant antioxidant activities. These polyphenols are mainly composed of dihydrochalcones; hydroxycinnamic acids; flavan-3-ols and flavonols (Fromm et al., 2012, Fromm et al., 2013, Xu et al., 2016). From these compounds, phloridzin, a chalcone derivative, is known as the characteristic polyphenol of apple and it protects the plant against some pathogens (Mikulic Petkovšek et al., 2008). It has antidiabetic effect by interfering glucose adsorption by inhibition of the sodium-linked glucose transporters (Manzano and Williamson, 2010). In addition, this important compound has antioxidant activity; therefore, it can inhibit lipid peroxidation and a series of new bioactive functions of this compound have been reported recently, such as prevention of bone loss, enhancement of memory and life extension as well as inhibition of cancer cell growth (Baldisserotto et al., 2012). Nair et al. (2014) reported that fatty esters of phloridzin have potential chemotherapeutic effects against human liver cancer cells through different mechanisms. Therefore, since the discovery of these properties of apple seeds and its constituents, it has been stated that they can be evaluated in different sectors such as food, pharmacy and cosmetic (Arain et al., 2012; Fromm et al., 2013). For this aim, different efforts are needed to increase the economic value of these seeds and to benefit from their potential health effects.

Among food products, chewing gum is widely consumed all over the world and has potent for delivering of bioactive compounds. As well as usual consumption, its formulations have been evaluated for several drugs and plant materials so as to improve their releasing and bioavailability (Paradkar et al., 2016). Therefore, it has been used as a drug delivery system in some medical treatments and stated that the gum formulations offer several advantages over the tablet or liquid formulations (Swamy et al., 2012). The benefits of chewing gum in medical applications include local and systemic effect, consumption without water, high acceptance by children and teenagers, fewer side effects, suitable stability and effective on the dry mouth (Aslani and Rostami, 2015). Besides all these, taking into account that the mild production conditions, having the longest duration of staying in mouth compared to other foods and low dose active ingredients are being the prime candidates for the formulation (Chandran et al., 2014, Konar et al., 2016); it turns out that chewing gum may be a potential delivering material in the administration of bioactive compounds.

To the best of our knowledge, no study has been carried out on the evaluation of defatted apple seeds in food products and therefore, the first purpose of this research is to determine the phenolic profiles and antioxidant activities of the phenolic extracts obtained from defatted seed flours of 5 different commercial apple cultivars after oil extraction. Secondly, considering the advantages of chewing gum as a potential delivering system and scientific studies based on the effects of phloridzin as an antioxidant and antimicrobial agent, it was decided to formulate a new chewing gum with defatted apple seed flour and to determine the dissolution kinetics and mechanism of phloridzin from the chewing gum matrix.