Optimising a stevia mix by mixture design and napping: A case study with high protein plain yoghurt

Abstract

A high protein plain yoghurt formulation was optimised using the Euclidian distance on the Napping® test, measuring the distance among formulations sweetened with stevia and standard samples sweetened with sucrose and sucralose. The optimised formulation was validated through temporal dominance of sensations and acceptance tests. The required amounts of the stevias to provide, at a minimum cost, the same sensory characteristics as the standard samples were 55% of stevia 1 (75% rebaudioside A + stevioside), 5% of stevia 2 (95% rebaudioside A), and 40% of stevia 3 (50% rebaudioside A), which was the best stevia mix found in this study. The stevia mix was an excellent alternative in high protein plain yoghurt, since its sensory profile was very similar to those of sucrose and sucralose. Additionally, there was no significant difference with respect to consumer acceptance.

Introduction

Yoghurt is a very popular product consumed in several countries, regardless of their human development index (Cruz et al., 2013; Hoppert et al., 2013; Huertas, 2012). From a nutritional perspective, yoghurt is widely perceived as a healthy food as it contains several proteins, riboflavin, vitamins B6 and B12, and calcium (O'Sullivan et al., 2016). Despite the healthy components of yoghurt, one must consider that traditional formulations of this product still employ sucrose, whose excessive consumption is linked to several health disorders (Imamura et al., 2015; Lustig, Schimidt, & Brindis, 2012).

Recent work in the literature has aimed at developing new yoghurt formulations without sucrose or with a reduced amount of sucrose (McCain, Kaliappan, & Drake, 2018). The most prominent strategies for reducing the sucrose content in yoghurt are ultrafiltration (Karam, Gaiani, Hosri, Burgain, & Scher, 2013), lactose hydrolysis (Whalen, Gilmore, Spurgeon, & Parsons, 1988), the partial reduction of sucrose (Chollet, Gille, Schmid, Walther, & Piccinali, 2013), and the replacement of sucrose by sweeteners (Drake, Gerard, & Chen, 2001; Pinheiro, Oliveira, Penna & Tamine, 2005; Reis et al., 2011).

Sweeteners are substances with a very intense sweet taste and are used in small amounts to replace the sweetness of a much larger amount of sucrose. Several sweeteners are available on the market, such as aspartame, acesulfame-k, neotame, cyclamate, alitame, among others. One of the most proeminent and important sweeteners, as an alternative to sucrose in food products, is sucralose (Chattopadhyay, Raychaudhuri, & Chakraborty, 2014). Sucralose is an artificial sweetener derived from sucrose (Binns, 2003; Chattopadhyay et al., 2014) with a similar sensory profile, possessing low levels of acidity and bitterness, and a sweetness intensity approximately 600 times greater than that of sucrose (Greenly, 2003; Shankar, Ahuja, & Sriram, 2013).

Despite this, sucralose is being replaced by natural sweeteners, following a healthiness-based market tendency (Hung, de Kok, & Verbeke, 2016; Saba et al., 2019; Shangguan et al., 2019), as consumers are seeking more natural and healthier products (Khan, 2015; Philippe, De Mey, Anderson, & Ajikumar, 2014) with low sucrose content (Vidigal et al., 2015). Natural sweeteners add value in terms of healthiness by reducing calories and using ingredients obtained from natural sources.

Stevias are natural sweeteners that can be used as alternatives to sucrose. They have low caloric content and a sweetness intensity approximately 300 times greater than that of sucrose (Barroso et al., 2016; Lemus-Mondaca, Vega-Gálvez, Zura-Bravo, & Ah-Hen, 2012; Philippe et al., 2014). Different stevias available in the market contain differences in the content of steviol glycosides (Narayanan, Chinnasamy, Jin, & Clark, 2014), and sweetness potency is directly proportional to their concentration (Gasmalla, Yang, & Hua, 2014; Pawar, Krynitsky, & Rader, 2013; Philippe et al., 2014). Hence, the use of stevias as a mix is a way of overcoming the limitations of each stevia separately, while also improving the taste and stability of the final product (Reis et al., 2011). Thus, each stevia has different characteristics and market values, and a product with high sensorial quality and with a good cost-benefit relationship could be developed by combining different types of stevia.

Numerous studies, especially those in the field of sensory science, have indicated the benefit of maximising the value achieved using time and resources, thus necessitating the application of efficient techniques for the development of new products (Dooley, Threlfall, & Meullenet, 2012; Rocha et al., 2020; Souza et al., 2012; Yang, Lu, & Hu, 2014). Optimisation methods are very important in sensory science because they are able to determine optimal levels of components or ingredients in a formulation (Cornell, 2011), allowing for the development of new formulas and thus guiding development of new products (Dooley et al., 2012).

In addition to optimisation techniques, there has been an increasing demand in recent years for alternatives to existing descriptive sensory analysis techniques (Vidal et al., 2014). It is important to emphasise the need for more economical, less time-consuming descriptive methods that can be performed with untrained panellists while maintaining the robustness of the information obtained (Fleming, Ziegler, & Hayes, 2015; Reinbach, Giacalone, Ribeiro, Bredie, & Frøst, 2014).

This study formulates an optimised mix of stevias for a high protein plain yoghurt. This mix was computed using three techniques. The first is the mixture design (Akonor et al., 2017; Baugreet, Kerry, Allen, & Hamill, 2017; Ekpong, Ngarmsak, & Winger, 2006; Santos, Fratelli, Muniz, & Capriles, 2018; Souza et al., 2012), which is a simple and efficient technique to determine the ideal formulation of food products. The second is the Napping® (Pagès, 2003, 2005), which is a fast and economic descriptive sensory test, able to quantify and qualify differences and similarities among products. The last is response surface methodology (Monaco, Miele, Cavella, & Masi, 2010), which is employed to compute the optimised mix of stevias. It is a graph that shows the interactions among the different components of a formulation and their resulting sensory response (Souza et al., 2012; Wai, Alkarkhi, & Easa, 2009), taking into account the market cost of each stevia and the similarity in the sensorial perception regarding standard high protein plain yoghurt samples sweetened with sucrose and sucralose.

Hence, the objective of this study is to optimise a mix of different stevias for a high protein plain yoghurt using the mixture design model with the Napping® and response surface methodology. The optimised formulation is validated using temporal dominance of sensations (TDS) analysis and consumer acceptance tests.