Retention of saffron bioactive components by spray drying encapsulation using maltodextrin, gum Arabic and gelatin as wall materials

Home > Blog

Highlights

Saffron bioactive components were encapsulated using different wall materials.
A mixture of maltodextrin, Arabic gum and gelatin resulted in highest encapsulation efficiency.
Total solids significantly affected microcapsule properties and saffron components retention.
Over 80% retention of crocin, picrocrocin and safranal was achieved during spray drying encapsulation.

Hamid Rajabi ^a, Mohammad Ghorbani ^a, Seid Mahdi Jafari ^a, Alireza Sadeghi Mahoonak ^a, Ghadir Rajabzadeh ^b

^a: Department of Food Materials and Process Design Engineering, University of Agricultural Sciences and Natural Resources, Gorgan, Iran

^b: Research Institute of Food Science and Technology, Mashhad, Iran

Received 22 February 2015, Revised 25 May 2015, Accepted 27 May 2015, Available online 5 June 2015, Version of Record 12 June 2015.

Abstract

Saffron as the world’s most expensive spice is very sensitive and loses its active compounds in exposure to environmental conditions. In this work, microencapsulation of saffron extract by various biopolymers was studied as an effective way to preserve its active compounds. Emulsions with a constant ratio of saffron extract/wall material of 1:20 and two levels of total solids (TS of 30 and 40%), were prepared using a homogenizer, and then spray dried. Powders were characterized in terms of powder yield, encapsulation efficiency, and retention of saffron active components, microstructure, and moisture content. Retention of picrocrocin, safranal and crocin after spray drying was analyzed by measuring absorbance at 257, 330 and 440 nm, respectively. It was observed that a mixture with 40% TS consisting of maltodextrin, gum Arabic and gelatin in the weight ratio of 0.94:0.05:0.01 retained the highest amount of picrocrocin, safranal and crocin, by retention values of 90.06, 80.37, and 91.03%, respectively. Both encapsulation efficiency and powder yield were positively influenced by total solids content, which could be related to the emulsion viscosity and droplet size. To conclude, a mixture of maltodextrin, gum Arabic and gelatin was efficient for saffron extract encapsulation by spray drying.

Graphical abstract

SEM of spray-dried saffron microcapsules at 30% TS with MD–GA–GE (85:10:5).

Introduction

Saffron from about 3000 years ago has been cultivated and used because of its unique features (Deo, 2003). Saffron, the dried and colored-red stigma of Crocus sativus L., belongs to the Iridaceae family, and is produced largely in Asia (particularly Iran) (Fernández and Pandalai, 2004, Kafi et al., 2006, Khazaei et al., 2014, Xuabin, 1992). Today, saffron has found many uses ranging from fragrances to dyes and medicines (Melnyk, Wang, & Marcone, 2010). In recent years, despite of its high price, the use of saffron is steadily increasing, due to changes of consumer preference towards natural products having functional properties (Knewstaubb & Henry, 1988).

Three main active compounds identified in saffron are crocin, picrocrocin and safranal (Carmona et al., 2006, Nassiri-Asl and Hosseinzadeh, 2014, Tarantilis et al., 1994) which lose their nature when exposed to light, heat and oxygen. Crocin and picrocrocin undergo to oxidation and hydrolysis reactions; meanwhile safranal, which causes the fragrance in saffron, is volatile at ambient temperatures. Therefore, encapsulation of saffron extract could result in a powder with a longer shelf life.

Encapsulation is defined as a protective method for active compounds which are sensitive to environmental conditions (Ahmed et al., 2010, Borgogna et al., 2010, Jafari et al., 2008, Medina-Torres et al., 2013, Saénz et al., 2009). On the other hand, during encapsulation, active compounds are packaged within a matrix or membrane (Akhavan, Jafari, Ghorbani, & Assadpoor, 2014). Encapsulation of herbal products could improve process capability, easy maintenance and low cost delivery, protect against environmental conditions and improve final product qualities (Deladino et al., 2008, Shu et al., 2006).

Among several encapsulation techniques, spray drying is the effective and most common one in the food industry (Jafari et al., 2008, Pang et al., 2014, Ré, 1998, Reineccius, 2001, Reineccius, 2004, Shahidi and Han, 1993), and one of the oldest encapsulation methods. The method consists of liquid atomization into small droplets, a drying step carried out using a warmed gas and collection of the solid particles (Beck-Broichsitter, Schmehl, Seeger, & Gessler, 2011). Selection of appropriate wall materials is one of the main steps in microencapsulation process (Pang et al., 2014). Common microencapsulation agents such as gum Arabic (GA) and maltodextrin (MD) are often used for herbal or plant-related products (Bhusari et al., 2014, Fazaeli et al., 2012, Janiszewska, 2014, Şahin-Nadeem et al., 2013, Silva et al., 2014, Turchiuli et al., 2014). For instance, Khazaei et al. (2014) employed two biopolymers, namely MD and GA to microencapsulate the anthocyanins of saffron petals. Furthermore, Castro-Muñoz, Barragán-Huerta, and Yáñez-Fernández (2014) investigated the spray drying microencapsulation of clarified juice extracted from purple cactus pear using gelatin (GE) and MD.

There is no information available on microencapsulation of saffron extract by spray drying. Most of the works in literature deal with microencapsulation of colorants (Barbosa et al., 2005, Rocha et al., 2012, Shu et al., 2006), flavors (Baranauskienė et al., 2006, Bayram et al., 2005, Liu et al., 2004, Reineccius, 1988, Reineccius et al., 1995) or essential oils (Kanakdande et al., 2007, Rosenberg et al., 1990, Soottitantawat et al., 2004, Soottitantawat et al., 2005, Soottitantawat et al., 2003) alone, but saffron stigma has all three type of these ingredients and therefore, microencapsulation of its extract, is a complex process. Crocin is a water-soluble glycosidic carotenoid responsible for color, picrocrocin causes a bitter-taste and safranal is the main volatile oil present in saffron (Caballero-Ortega, Pereda-Miranda, & Abdullaev, 2007).

The objective of this work was to study the microencapsulation of saffron extract by spray drying with binary and ternary blends of MD, GA, and GE as wall materials. The microcapsules were evaluated for the retention of saffron active components, moisture content and encapsulation efficiency. Scanning electron microscopy was also used to observe the microstructural characteristics of encapsulated powders.

Section snippets

Saffron powder preparation

Saffron was picked before sunlight from a farm around Torbat-E-Heydariyeh (Iran). Stigmas were separated from the other part of flowers. In order to determine the optimal drying method, three methods were pre-investigated considering drying at room temperature (25 °C ± 1), dehydration with electrical oven (60 °C ± 1), and microwave drying (1000 W). Our results showed (data not given) that the highest content of saffron active components (SAC) was obtained when saffron treated at higher

Effect of TS on the retention of saffron bioactive components during encapsulation

The average values of encapsulation efficiency for SAC are shown in Fig. 1. With respect to the total solids content, this variable had a positive effect on the encapsulation efficiency, i.e., higher solids content resulted in higher encapsulation efficiencies. It is shown that the most important factor determining the retention of volatiles and encapsulation efficiency of food oils during spray drying is the dissolved solids content in the feed (Jafari et al., 2007a, Jafari et al., 2007b). Our

Conclusion

The present study describes the use of three types of wall materials i.e. maltodextrin, gum Arabic and gelatin for the microencapsulation of saffron extract using spray-drying technique. Total solids content had a positive influence on the encapsulation efficiency and the SAC retention. These results could be related to emulsion properties, mainly viscosity. Higher solids concentration leads to bigger particle sizes, lower moisture contents and higher powder yields. As far as the blends were

Acknowledgment

Iran National Science Foundation (grant number 90000994) and the Research Institute of Food Science and Technology should be acknowledged for their financial support.