Lab Report

Laboratory 1 – FOOD 607 SENSORY SCIENCE AND TECHNIQUES

Date: 11/07/2019 Name: John Smith Student ID: 12345

D-tagotose as sucrose substitute on the acceptability of strawberry-flavoured yogurt

INTRODUCTION

Yogurt, which exhibits healthy and desirable sensory attributes, is increasingly being consumed worldwide (Hoppert et al., 2013). The development of low-sugar and low-calorie yogurt products has been the focus of the food industry since the discovery of alternative sweeteners (Cinbas & Yazici, 2008). Past studies have shown that sugar reductions in foods can produce a reduction in the product acceptability (Nikooie, Ghandehari Yazdi, & Shamsaei, 2015). Sugar replacers or substitutes, also known as alternative sweeteners, are food additives that mimic the sweet taste of sugar without having higher amounts of calories (Chattopadhyay, Raychaudhuri, & Chakraborty, 2014). The food industry is increasingly replacing sugar with alternative sweeteners in traditional food products (Tandel, 2011).

Recently, an emerging sweetener known as D-tagatose has drawn a lot of attention in the food industry. D-Tagatose, commonly referred to tagatose, is a stereoisomer of fructose that inverts its hydroxyl and hydrogen group on the fourth carbon (Koh et al., 2013). It is a rare sugar that provides a sweet sucrose-like taste, but with less intensity (90-92% of sucrose sweetness) and half of the calories (1.5 kcal/g) (Levin, 2002; Muddada, 2012). Tagatose is reported to have similar physical and sensory characteristics as sugar, and it has been suggested for using as a sugar replacer. Therefore, the incorporation of tagatose may offer desirable sensory characteristics in sugar-reduced products.

Affective responses of products can be measured using liking and preference measurements. The 9-point hedonic scale is the primary tool to evaluate product liking in the food industry (Torrico et al., 2018). This scale has the advantage of measuring a wide range of attributes. It uses parametric statistics to analyse the differences in acceptability from different products. Due to these aforementioned characteristics, this scale is suitable for measuring the acceptability of yogurt products.

OBJECTIVE

The objective of this study was to evaluate the effects of tagatose as a sugar substitute on the sensory acceptability of strawberry-flavoured yogurts using the 9- point scale.

MATERIALS AND METHODS

Materials

Six different formulations were used for the sensory tasting session (Table 1). These formulations had different levels of sugar and different levels of tagatose. Before the sensory session, samples were poured into 1.5 L plastic container with lids (Woolworths Group, Bella Vista, NSW, Australia) and transferred to a cold room under 4 °C for a period of 12 hours.

Laboratory 1 – FOOD 607 SENSORY SCIENCE AND TECHNIQUES

Table 1. Formulations1 of the different sucrose concentrations for the strawberry-flavoured yogurt samples

Treatment label Concentration of

sucrose Concentration of tagatose

Proportions of sucrose and tagatose1

Suc (100%) 8.5 g/100 g yogurt 0.00 g/100 g yogurt 100 % Sucrose,

0% Tagatose

Suc (80%)/Tag (20%) 6.8 g/100 g yogurt 1.85 g/100 g yogurt 80 % Sucrose,

20% Tagatose

Suc (60%)/Tag (40%) 5.1 g/100 g yogurt 3.70 g/100 g yogurt 60% Sucrose,

40% Tagatose

Suc (40%)/Tag (60%) 3.4 g/100 g yogurt 5.54 g/100 g yogurt 40% Sucrose,

60% Tagatose

Suc (20%)/Tag (80%) 1.7 g/100 g yogurt 7.39 g/100 g yogurt 20% Sucrose,

80% Tagatose

Tag (100%) 0.0 g 9.24 g/100 g yogurt 100% Tagatose

1 The yogurt sample with the sucrose concentration of 8.5 g/100 g represented the full sucrose sample (100%). The subsequent sucrose concentrations represent reductions from the initial sucrose concentration. The

sucrose/tagatose combinations were mixed with the pasteurized strawberry flavouring jam (5.5%) and blended into the pre-made yogurt

Sensory Evaluation

Subjects

A total of N = 55 untrained participants were recruited from a pool of staff and students

at The University of Melbourne, Australia via the university noticeboard. Consumer

evaluations took place in individual booths in the Sensory Laboratory at The University of

Melbourne under a controlled environment with illuminated modern LED lights (configured

with colour white; RGB = 255, 255, 255) and a set temperature of 25 °C.

Sensory procedure

Participants were asked to complete a consumer acceptance test on all six strawberry-

flavoured yogurt samples (Table 1). Each sample was poured into a 30 mL plastic cup

coded with a 3-digit random number. The presentation order of the samples was

randomized within each participant. Yogurt samples were evaluated with an internal

temperature of 4 ± 1 °C. Participants were asked to evaluate liking of appearance, colour,

glossiness, aroma, sweetness, sourness, aftertaste, thickness, smoothness, and overall

of each sample using a 9-point hedonic scale (1 = dislike extremely, 5 = neither like nor

dislike, 9 = like extremely). Participants used paper ballots for answering the questions.

Experimental Design and Statistical Analysis

Analysis of variance (ANOVA) with a generalized linear model (GLM) and a post-hoc Tukey’s Honestly Significantly Different (HSD) test (P ≤ 0.05) were used to assess significant differences in the hedonic ratings measurements of the strawberry-flavoured yogurt samples. Data analyses were performed using the XLSTAT (Addinsoft, New York, NY, USA) statistical software version 2017.

Laboratory 1 – FOOD 607 SENSORY SCIENCE AND TECHNIQUES

RESULTS The effects of tagatose substitution on the sensory liking/acceptability of strawberry-

flavoured yogurts are summarized in Table 2. All treatments were similar in acceptability,

with no significant (P ≥ 0.05) differences found on the liking scores of any attributes.

However, the treatment with 100% tagatose was generally lower but not significant (P ≥

0.05) in the liking scores of all attributes, except for colour and appearance. The 100%

sucrose treatment obtained slightly higher liking values for the visual attributes of

appearance, colour, and glossiness when compared to other yogurt treatments.

Table 2. Mean values1 for the sensory acceptability scores of the strawberry-flavoured yogurts

Treatments2 Appearance Colour Glossiness Aroma Sweetness

Suc (100%) 6.43 ± 1.45 a 6.57 ± 1.43 a 6.51 ± 1.27 a 6.38 ± 1.29 a 6.19 ± 1.69 a

Suc (80%)/Tag (20%) 6.04 ± 1.64 a 6.21 ± 1.23 a 6.28 ± 1.25 a 6.26 ± 1.48 a 6.02 ± 1.59 a

Suc (60%)/Tag (40%) 6.25 ± 1.30 a 6.26 ± 1.26 a 6.36 ± 1.16 a 6.11 ± 1.41 a 6.00 ± 1.83 a

Suc (40%)/Tag (60%) 6.25 ± 0.13 a 6.04 ± 1.19 a 6.30 ± 1.13 a 6.28 ± 1.41 a 6.40 ± 1.56 a

Suc (20%)/Tag (80%) 6.30 ± 1.34 a 6.25 ± 1.36 a 6.38 ± 1.21 a 6.49 ± 1.53 a 6.40 ± 1.60 a

Tag (100%) 6.13 ± 1.40 a 6.19 ± 1.37 a 6.23 ± 1.27 a 6.08 ± 1.34 a 5.67 ± 1.83 a

Treatments2 Sourness After-taste Thickness Smoothness Overall liking

Suc (100%) 6.30 ± 1.44 a 6.40 ± 1.76 a 6.15 ± 1.50 a 6.38 ± 1.42 a 6.68 ± 1.61a

Suc (80%)/Tag (20%) 6.13 ± 1.43 a 6.45 ± 1.51 a 6.17 ± 1.31 a 6.66 ± 1.19 a 6.49 ± 1.48 a

Suc (60%)/Tag (40%) 6.11 ± 1.49 a 6.26 ± 1.69 a 6.42 ± 1.41 a 6.55 ± 1.51 a 6.15 ± 1.68 a

Suc (40%)/Tag (60%) 6.30 ± 1.58 a 6.25 ± 1.49 a 6.17 ± 1.33 a 6.25 ± 1.12 a 6.30 ± 1.42 a

Suc (20%)/Tag (80%) 6.15 ± 1.51 a 6.25 ± 1.52 a 6.11 ± 1.59 a 6.28 ± 1.61 a 6.43 ± 1.58 a

Tag (100%) 5.66 ± 1.56 a 5.68 ± 1.72 a 5.89 ± 1.48 a 6.21 ± 1.45 a 5.94 ± 1.89 a

1 Values are represented as mean and standard deviation (N=55). The liking scores were based on a 9-point hedonic scale (1 = dislike extremely, 9 = like extremely).

2 Treatment labels are indicated in Table 1. a Mean values that share the same letter within the same variable are not significantly different (P < 0.05).

DISCUSSION

Tagatose substitutions showed no significant effects on the acceptability of all attributes compared to that of the 100% sucrose yogurt. These results are somewhat expected due to the similar sensory and physical characteristics of tagatose compared to sucrose (Levin, 2002; Muddada, 2012). Sugar and fruity or floral aromas interact with each other in the form of potentiation (Hewson, Hollowood, Chandra, & Hort, 2008). For the yogurt samples in the present study, the sugar may have potentially enhanced the strawberry flavour at the time of tasting. These results showed that there was a differential effect of tagatose and sucrose on the flavour perception despite the equal level of sweetness that was used for preparing the samples. Further investigations on the effect of tagatose on flavour release are needed to study these effects. The different formulation ratios of sucrose/tagatose had no significant effects (P ≥ 0.05) on the liking of all attributes. However, the 100% tagatose sample had consistently lower liking scores (but not significant) for all attributes compared to those of the other treatments (Table 2). The lower acceptability levels of the 100% tagatose sample in sweetness, sourness, and strawberry-flavour may be potentially related to a different perceived intensity level of these attributes.

Laboratory 1 – FOOD 607 SENSORY SCIENCE AND TECHNIQUES

CONCLUSIONS In general, strawberry yogurts with tagatose replacements had similar acceptability

scores for appearance, colour, glossiness, aroma, sweetness, sourness, aftertaste, thickness and smoothness. Biochemical and microbiological studies are also needed to examine the synergistic effects of tagatose and probiotics in yogurt products.

REFERENCES

Chattopadhyay, S., Raychaudhuri, U., & Chakraborty, R. (2014). Artificial sweeteners– a review. Journal of food science and technology, 51(4), 611-621.

Cinbas, A., & Yazici, F. (2008). Effect of the addition of blueberries on selected physicochemical and sensory properties of yoghurts. Food Technology and Biotechnology, 46(4), 434-441.

Hewson, L., Hollowood, T., Chandra, S., & Hort, J. (2008). Taste–aroma interactions in a citrus flavoured model beverage system: Similarities and differences between acid and sugar type. Food quality and preference, 19(3), 323-334.

Hoppert, K., Zahn, S., Jänecke, L., Mai, R., Hoffmann, S., & Rohm, H. (2013). Consumer acceptance of regular and reduced-sugar yogurt enriched with different types of dietary fiber. International Dairy Journal, 28(1), 1-7.

Koh, J. H., Choi, S. H., Park, S. W., Choi, N.-J., Kim, Y., & Kim, S. H. (2013). Synbiotic impact of tagatose on viability of Lactobacillus rhamnosus strain GG mediated by the phosphotransferase system (PTS). Food microbiology, 36(1), 7-13.

Levin, G. V. (2002). Tagatose, the new GRAS sweetener and health product. Journal of medicinal food, 5(1), 23-36.

Muddada, S. (2012). Tagatose: the multifunctional food ingredient and potential drug. Journal of Pharmacy Research, 5(1), 626-631.

Nikooie, A., Ghandehari Yazdi, A. P., & Shamsaei, M. (2015). Effect of sucrose replacement by Stevia as a non-nutritive sweetener and bulking compounds on physiochemical properties of foodstuffs. Journal of Herbal Drugs (An International Journal on Medicinal Herbs), 6(2), 121-128.

Tandel, K. R. (2011). Sugar substitutes: Health controversy over perceived benefits. Journal of pharmacology & pharmacotherapeutics, 2(4), 236.

Torrico, D. D., Fuentes, S., Viejo, C. G., Ashman, H., Gunaratne, N. M., Gunaratne, T. M., & Dunshea, F. R. (2018). Images and chocolate stimuli affect physiological and affective responses of consumers: A cross-cultural study. Food quality and preference, 65, 60-71.