Nanoliposomal encapsulation mediated enhancement of betalain stability: Characterisation, storage stability and antioxidant activity of Basella rubra L. fruits for its applications in vegan gummy candies

Highlights

• Basella rubra betalains were successfully loaded in nanoliposomes.

• Improved thermal stability was recorded for betalains nanoliposomes.

• Extended sonication time improved the stability and polydispersity index.

• Sensory score was acceptable for Betalains nanoliposomes fortified vegan gummy candies.

• Betalains nanoliposomes vegan gummy candies exhibited superior antioxidant activity.

Abstract

Betalains are violet-red, natural food grade pigments with health benefits; however, their stability limits its use in industrial food processing. This can be overcome by placing the betalains in lecithin nanoliposomes (NLs), which causes a 76% improvement of betalain colour and stability. Extended sonication time (8 min) lowered the zeta potential (–47.5 to –40.8), and particle size (74.23 to 55.35 nm). Zeta potential, particle size, and polydispersity index of Betalain NLs (BNLs) didn’t change significantly during storage (40 days). Degradation in the colour of BNLs was observed only at 121 °C (20 min) while the native juice degraded at 100 °C (20 min). BNLs were incorporated in gummy candies (GuCa) to improve its colour stability. The betalain retention, colour, texture, antioxidant activity, and shelf-life of the GuCa during storage (5 °C, 28 days) demonstrated the efficacy of BNLs to be explored as a natural colourant for the food industry.

Introduction

Betalains are nitrogen-containing, water-soluble, plant-based, natural pigments commonly found in 17 families of the order Caryophyllales (Khan, 2016a, Khan, 2016b). Beta vulgaris, Opuntia spp. Hylocereus undatus and Amaranthaceae are reported to be rich sources of betalains (Khan, 2016b, Fidelis et al., 2017). Betanin (E162) is the commercially available betalain component extracted from beetroot. It is widely used as a natural colourant in model food systems such as jams, ice creams, cakes, yogurts, and gummy candies (Amjadi, Ghorbani, Hamishehkar, & Roufegarinejad, 2018). In the current food processing industry, betalains have gained the attention of scientists, and end-users, due to their dietary, nutraceutical potential, cell reinforcement potential, and biological activity (Kumar, Manoj, & Giridhar, 2015). More significant is the activity of plant betalains to battle against a few disorders, for example, malignancy, aggravation, joint inflammation, neurodegenerative, and cardiovascular conditions (Carocho, Morales, & Ferreira, 2018). An emerging trend of the food industry for advancing fortified food formulations is to replace artificial colourants with natural pigments that exhibit health benefits (Kumar, Manoj, Shetty, Prakash, & Giridhar, 2015a).

Despite all the valuable wellbeing contributions, betalains are delicate to external conditions, for example, oxygen, temperature, light, pH, water action, and chemicals (Khan, 2016b). A few reports have shown betalains with improved stability, as evaluated and announced in fruits of Basella rubra (Khan, 2016b, Kumar et al., 2016). One improvement of betalain stability is the preparation of lecithin nanoliposomes (NLs). NLs are encouraging because of their capacity to encapsulate hydrophobic or hydrophilic molecules, and non–toxic quality of their endogenic lecithin (phosphatidylcholine) composition (Teo, Lee, Goh, & Wolber, 2017). The NLs, prepared with a thin-film hydration method, are a broadly utilized transport strategy for antimicrobial particles, nutrients, phenolics, and commercial betanin (Bangham et al., 1965, Coimbra et al., 2011).

Gummy candies (GuCa) are generally known for palatability and stability with natural pigment fortifications than in any other emulsification model. The encapsulated betalain incorporation to the GuCa food system should be visually attractive without any alteration of overall taste and texture already accepted by a substantial number of people. The increased bioactivity, efficient delivery, and bioavailability of quercetin NL encapsulation using different phospholipids such as rice bran, soy, and egg yolk phospholipids has been reported (Rodriguez, Almeda, Vidallon, & Reyes, 2019).

Hence, there are many post-preparation studies on NLs to check the strength of the NLs, for example, zeta potential, shape of the molecule, and polydispersity index (Rodriguez, Almeda, Vidallon, & Reyes, 2019). Physical and synthetic factors are considered to be involved in the stability of NLs and bioavailability (Wu, Zhang, & Watanabe, 2011). NL synthesis shows the oxidative strength that can be constrained by the use of antioxidant agents and storage conditions. Nevertheless, the colloidal stability of liposomes will be demonstrated by a higher zeta potential, with adequate particle charge to repulse one another (Du Plessis, Ramachandran, Weiner, & Muller, 1996).

Basella rubra L. (Basellaceae) is a commonly used green leafy vegetable in southern parts of India that accumulates betalains in its leaf (0.08 g/100 g fresh weight (FW)), and fruits (0.34 g/100 g FW). In B. rubra fruits, gomphrenin I is the major betalain pigment (Kumar et al., 2015, Kumar et al., 2015b). The in vitro antioxidant and anticancer activity of the B. rubra betalains on human cervical carcinoma cell lines have recently been reported (Kumar et al., 2015b). Similarly, the food application of betalains extracted from fruits of B. rubra as a natural colourant in ice cream formulation may also provide health benefits and increase the oxidative stability of ice cream (Kumar et al., 2015a). The improvement of commercial betanin NLs and its application in the preparation of GuCa with enhanced stability of betanin NLs was reported recently (Amjadi, Ghorbani, Hamishehkar, & Roufegarinejad, 2018). The exploration of betalain rich juice extract for the preparation of NLs with added nutritional and nutraceutical potentials will have great impact in the food processing industry for the development of thermally stable natural colours used in model food systems.

Accordingly, the present study focused on optimizing a method for the preparation of B. rubra fruit juice betalains NLs (BNLs). BNLs were dispersed by ultra-sonication (probe) method and its influence in the bioactive properties of the liposomes was evaluated. Further, storage and temperature stability of BNLs were assessed. Studies were also conducted to incorporate BNLs in vegan GuCa to propose BNLs as a thermally stable, natural colourant. Vegan GuCa formulation, with added health benefits, could combat the gelatin-based GuCa available in the market.