NFS Journal 13 (2018) 1–9 Contents lists available at ScienceDirect NFS Journal journal homepage: www.elsevier.com/locate/nfs Original article A potential natural coloring agent with antioxidant properties: Microencapsulates of Renealmia alpinia (Rottb.) Maas fruit pericarp Jimenez-Gonzalez O.a, Ruiz-Espinosa H.a, Luna-Guevara J.J.a, Ochoa-Velasco C.E.b, ⁎ Luna Vital D.c, Luna-Guevara M.L.a, a Ingenieria en Alimentos, Facultad de Ingenieria Quimica, Benemerita Universidad Autonoma de Puebla, 14 Sur y Av. San Claudio, Ciudad Universitaria, Col. San Manuel, 72420, Puebla, Puebla, Mexico. b Departamento de Bioquimica-Alimentos, Facultad de Ciencias Quimicas, Benemerita Universidad Autonoma de Puebla, 14 Sur y Av. San Claudio, Ciudad Universitaria, Col. San Manuel, 72420, Puebla, Puebla, Mexico. c Department of Food Science and Human Nutrition, University of Illinois at Urbana, Champaign, IL 61801, United States. ARTICLE INFO ABSTRACT Keywords: Microencapsulates of ethanolic extracts of Renealmia alpinia (Rottb.) Maas fruit pericarp were obtained by spray Encapsulates drying. Physicochemical properties (pH, °Bx, titratable acidity, maturity index, moisture content and color), Antioxidant properties bioactive compounds (anthocyanins and other phenolic compounds) and antioxidant capacity of the fresh fruit Renealmia alpinia (Rottb.) Maas pericarp were assessed. Microencapsulates were produced by feeding a 1:3 mixtures of ethanolic extracts (en- Pericarp capsulated material) and different encapsulating agents (maltodextrin, gum arabic and a 1:1 mixture of both) to Spray drying the spray dryer. Physical properties (yield, particle size, moisture, color, wettability, bulk and compact densities) Pigment of the resulting powders were determined while both stability of antioxidant compounds and maintenance of antioxidant capacity were evaluated during a 28-day storage at 4 and 25 °C. Fresh pericarp was an important source of phenolic compounds and anthocyanins which heavily contributed to fruit color parameters. The highest yield 21.58% and moisture content 2.45% were observed in powders with 1:1 maltodextrin-gum arabic ratio. Gum arabic microencapsulates better preserved anthocyanins (10.37 ± 2.38, 11.65 ± 0.58, mg Cyd-3- Glu/g) and phenolic (7.58 ± 0.51, 8.70 ± 1.28 mg GAE/g) at both storage temperatures 4 and 25 °C, re- spectively. Two individual anthocyanins were identified by HPLC: cyanidin-3-O-glucoside and delphinidin-3-O- glucoside. While maltodextrin capsules exhibited increased stability of antioxidant compounds and activity at 4 °C storage. Evaluated microencapsulates might represent a suitable alternative as a natural coloring agent with potential antioxidant activity. 1. Introduction altering histamine release and hypersensitivity [3]. Besides, at very high intake of synthetic colorants have been related to a higher in- The food industry regularly uses both natural and synthetic ad- cidence of chronic degenerative diseases such as cancer [4]. In addition, ditives to help maintaining sensory characteristics in the final product well beyond their role as coloring agents, it is well known that natural such as flavor, color and texture or to improve their technological pigments may act as antioxidant agents, thus conveying additional performance. Among substances added to foodstuffs, coloring agents benefits to human health [5,6]. The most common natural pigments are some of the most widespread used as they play a key role in im- found in food sources, especially fruits and vegetables, include car- proving quality perception and product acceptability [1]. In this sense, otenoids, chlorophylls, betalains and anthocyanins [5,7]. coloring agents are required to compensate for color modifications About 23,500 different plant species can be found in Mexico; a high suffered by the product throughout processing and during storage [2]. proportion of these is used in rural communities throughout the country However, the utilization of synthetic colorants is controversial as sev- as sources of foods, beverages, medicines, tools, fuels, among others eral studies have shown that they may have harmful effects on chil- [8,9]. In particular, the Northern Puebla State possess a great diversity dren's health, contributing to hyperactivity, attention deficit and other of edaphoclimatic conditions that allows both growth and, in certain behavior disorders; besides, they may intensify asthma symptoms by cases, exploitation of several vegetable resources, such as Renealmia ⁎ Corresponding author: Colegio de Ingenieria en Alimentos, Facultad de Ingenieria Quimica, Benemerita Universidad Autonoma de Puebla, Puebla, Mexico. E-mail address: [email protected] (M.L. Luna-Guevara). https://doi.org/10.1016/j.nfs.2018.08.001 Received 15 May 2018; Received in revised form 31 August 2018; Accepted 31 August 2018 Available online 05 September 2018 2352-3646/ © 2018 The Authors. Published by Elsevier GmbH on behalf of Society of Nutrition and Food Science e.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/). O. Jimenez-Gonzalez et al. NFS Journal 13 (2018) 1–9 alpinia (Rottb.) Mass (Zingiberaceae) [10], a wild plant locally known 2.3. Production of encapsulates as xkijit (in Totonac language) with edible fruits. The yellow seeded pulp is consumed, while pericarp is discarded; however, the latter ex- 2.3.1. Preparation of feeding mixes hibits an intense dark red color that might be used as a source of natural Maltodextrin (MDX) with dextrose equivalents of 4.0–7.0 (Sigma- colorants. From the food safety standpoint, this is feasible as [11] re- Aldrich, USA) and gum arabic (GA) (Meyer, Mexico) were used as en- ported that pericarp is innocuous for human consumption, while Vega- capsulating agents (EAs). Ethanolic extracts were mixed with the en- Arroy et al. [12] reported that pericarp tissue is rich in phenolic com- capsulating agents in a 1:3 ratio, adjusting solids to 20°Bx [19]. Three pounds and anthocyanins with high antioxidant capacity. It is well different EAs proportions were used: MDX only, a 1:1 weight mixture of known that, these compounds and other antioxidants are unstable when MDX and GA (MDX:GA) and GA only; all mixtures were homogenized at exposed to different environmental conditions like sunlight, oxygen, room temperature using a magnetic stirrer. pH, etc. [13]; consequently, different techniques have been developed to protect them from such factors. Spray-drying microencapsulation has 2.3.2. Spray drying been used as a suitable alternative for protecting fruit-obtained natural Mixtures were fed to a bench-top spray dryer (SEV Prendo, Mexico) pigments (anthocyanin, carotenoids, etc.) preserving their antioxidant equipped with a 0.5 mm atomizer. A fixed flow rate of 40 ± 1 mL/min properties [14]. was provided by a peristaltic pump. The dryer was operated at an inlet fi During encapsulation with spray-drying, a polymer lm coats a tiny temperature of 150 ± 2 °C and an outlet temperature of 98 ± 2 °C, liquid droplet containing the compound of interest, which is later dried while rotation speed and air pressure were fixed. Mixtures were kept in a chamber where the microcapsule or microsphere is formed [15,16]. under constant agitation at 22 °C throughout the encapsulation process. As dehydration rapidly takes place, the appropriate selection of wall material and operating conditions is paramount for developing a suc- cessful encapsulation operation; besides, microencapsulate properties 2.4. Physical analysis of encapsulates might change depending on storage environments. Thus, this research deals with the formation of spray-dried microencapsulated pigments 2.4.1. Yield obtained from the ethanolic extract of R. alpinia fruit pericarp using Encapsulation yield was determined as described by Fang and selected wall materials, evaluating the maintenance of both color and Bhandari [20] using the following expression. antioxidant-related features (including anthocyanins, phenolic com- Powder obtained by spray drying() g Yield = × 100 pounds contents and antioxidant capacity) after processing and during Fruit concentrate() g+ EA () g (3) storage at selected temperature conditions. where: EA is the encapsulating agents used. 2. Materials and methods 2.4.2. Moisture Powder moisture was obtained gravimetrically by drying a 1 g 2.1. Raw material and physicochemical characterization powder sample in a convection oven at 105 °C to a constant weight [17]. Renealmia alpinia fruit samples were provided by a local producer from Northern Puebla, Mexico. Only damage-free fruits, with similar maturity stage were used. Upon arrival, pericarp was manually re- 2.4.3. Water activity (aw) moved from the pulp, placed and sealed in polyethylene bags and kept Water activity of encapsulates was obtained using a dew point hy- at −15 °C until used. Moisture, pH, titratable acidity, fruit soluble so- grometer (Aqualab Series 3TE) loading the cell with a 3 g sample. lids (°Bx) were determined, according to AOAC [17]. Maturity index was determined as °Bx/titratable acidity ratio. 2.4.4. Wettability Wettability was defined as the time required for a 0.1 g powder sample spread over the surface of 100 mL of distilled water at 25 °C to 2.1.1. Color completely submerge into the liquid [21]. CIE L*, a*, b* color parameters of both pericarp and micro- encapsulates were determined using a tristimulus colorimeter 2.4.5. Compact and bulk density (HunterLab, ColorFlex 45/0 Spectrophotometer); these parameters Bulk density was determined as the volume occupied by 2.5 g were used to calculate chroma (Eq. (1)) and hue (Eq. (2)) values. powder in a 10 mL graduated cylinder. Meanwhile, the Tappin method was used for compact density determination, where the sample was hit C∗ =+(a∗221/2 b∗ ) (1) on the flat surface up to a constant sample volume [22]. H°−∗∗= tan1 (b /a ) (2) 2.4.6. Microcapsule morphology Microcapsule morphology was observed by scanning electron mi- croscopy (SEM). The powder was placed on a sample holder and fixed with double-sided tape. Later, it was gold-sputter coated and observed 2.2. Pigment extraction in a Quanta FEG 250 SEM (FEI, USA).