ABSTRACT

       A cocktail can be defined as a combination of alcohol, sugar, water and fruit.  This study aimed to increase consumer preference for commercial cocktails through the use of additional sweeteners and gums.  Consumer preference for a Tesco Sea Breeze product was increased by increasing the sugar level to 11.88% w/w. Additional work at a total sweetener level of 11.88% w/w involving sugar substitution with glucose and satigum proved successful in increasing consumer preference. It is recommended that the commercial partner modify the existing Tesco Sea Breeze recipe to include 8.92%w/w sugar + 2.91% w/w glucose +0.05%w/w satigum. Modifying other commercial cocktail formulations (X on the Beach, Oscar Peach Cocktail and Strawberry Daiquiri) to incorporate 8.92%w/w sugar + 2.91% w/w glucose +0.05%w/w satigum did not significantly alter consumer preference

Key words: Cocktails, Sugar, Glucose, Satigum, Sensory evaluation, Consumer preference

INTRODUCTION

        Cocktails are popular alcoholic drinks which can now be purchased in off licenses and supermarkets as well as from the bar trade. A cocktail is defined by SaskyCom and PJI-Designs (1999)¹ as a combination of alcohol, sugar, water and fruit and by Cross (1996) ² as a stimulating liquour, composed of spirits of any kind, sugar, water and bitters. The composition of cocktails can vary depending on style and individual consumer preferences. Nowadays cocktails can be used for many occasions such as celebrations, leisure drinking and business drinking.³

The most common sweetener used in the beverage industry is sucrose.⁴ Sucrose is often used for liqueurs and cocktails as it does not undergo the Maillard browning reaction and so does not create off-colours. Glucose is the most commonly used monosaccharide in foods. Generally, Glucose is less sweet than sucrose and fructose. Thickeners are used to promote viscosity, increase firmness and cause gelation in a food system. Satigums are the most common processing aids that serve to thicken and/or emulsify cocktails.⁵

        The quality of commercial cocktails are judged on their sensory quality, namely visual appeal, aroma, taste, texture and mouthfeel, although the former is less important with commercial cocktails.⁶ It is hard to define the term ‘texture’ as it depends on the state of the food system. Jowitt (1974) ⁷ defines texture as the attribute of a substance resulting from a combination of physical properties and perceived by the sense of touch, sight or hearing. The physical properties may include size, shape, number, nature, and conformation of constituent structural elements. Texture is influenced by the presence of texturizing ingredients. As a physical characteristic of food, texture can be evaluated by human sensory perception. Mouthfeel and food texture are closely related parameters.⁸ Mouthfeel includes the entire spectrum of a food’s physicochemical characteristics inside the mouth, from the initial sensation inside the oral cavity to the bite, through chewing or swallowing in case of beverages.⁴ Viscosity is a very important parameter for measuring the quality of cocktails. Bourne (2002)⁹ defined viscosity as the fluid’s internal friction or its resistance to flow.

Sensory evaluation is a scientific method that can be used to judge the acceptability of cocktails. Sensory evaluation is the assessment of the qualities of a food made by human senses. It describes food texture, flavour, aroma and even tactile response.¹⁰ Sensory evaluation can be assessed in different ways. The triangle test is a discriminatory testing method which is usually used in product development studies to determine if various ingredient substitutions or changes in processes will result in adverse product effects.¹¹ The paired preference test is a discrimination test which is widely used to determine consumer preference and acceptance. This method is similar to the triangle test, however fewer samples are required and there is less tatting.¹² Hedonic scales are frequently used in sensory evaluation. Stone (1993)¹³ reported that the Hedonic scale was used to evaluate the acceptability of food items. It is a descriptive test method to describe specific product attributes such as flavour, texture, mouthfeel, and so forth, by quantifying the perceived intensities of specified sensory characteristics.

        The overall aim of this project is to increase consumer preference for commercial cocktails through the use of additional sweeteners and gums. To achieve this overall aim, a number of objectives were set. The first objective is to determine the effect of increasing sugar content in a commercial cocktail (Sea Breeze) on consumer preference. Based on the results, other objectives were then defined. First, to determine the threshold level of sugar substitution with glucose which could be detected by consumers in an enhanced sugar level commercial cocktail (Sea Breeze). Second, to determine if consumers prefer the partial replacement of sugar with glucose in an enhanced sugar level commercial cocktail formulation (Sea Breeze). Third, to determine the threshold level of substitution of glucose with a gum which can be detected by consumers in an enhanced sugar and glucose level commercial cocktail formulation (Sea Breeze). Fourth, to determine the effect of increasing gum level on the consumer perception of sweetness, thickness and alcohol bite in an enhanced sugar and glucose level commercial cocktail formulation (Sea Breeze). Last, to determine if consumers prefer an enhanced sugar, glucose and gum formulation over the existing commercial formulation (Sea Breeze, X on the Beach, Oscar Peach Cocktail and Strawberry Daiquiri).

MATERIALS AND METHODS

Materials

Ingredients used were water, neutral spirit, Ferment 4 wine, satigums, glucose powder, granulated sugar, antifoam, Sea Breeze concentrate, clouding agent, peach flavour, lemon flavour, rum flavour, citric acid powder, malic acid powder, sodium benzoate, strawberry concentrate pulp, and orange concentrate pulp. All were supplied by the commercial partner.  Equipment used was a vortex magnetic stirrer, electric kettle, beakers, containers, glass rods and a laboratory bottle filling machine.  All were provided by the commercial partner at its production site. One litre clear bottles and caps, and sensory evaluation cups (7cl) cups provided by the commercial partner. Rinsing water was provided by the University.

Sample Preparation

The cocktail formulations were prepared at the commercial partner’s laboratory. The Cocktail samples preparation is simply a blending operation. Approximately two litres of boiling water was first added to a 5 litre beaker. Next all the ingredients except alcohols were mixed together in the vortex magnetic stirrer for about 5 minutes until homogenous. The mixture was cooled in a (room temperature) water bath, and when the sample temperature dropped below 40^oC the alcohols were added. The samples were then stirred using a glass rod. Finally, the samples were transferred to bottles and packaged by a packing machine. The manufacturing process is shown in Fig .1.  Sensory evaluation was carried out the day after the samples were prepared. To minimize flavors change, samples were placed in a chiller until the sensory evaluation time.

Sensory evaluation

The sensory evaluation sessions were conducted in a teaching laboratory at UUC. Different numbers of untrained food technology management students were used in the panels for the five sensory evaluation sessions. The first session involved a simple preference test. Five samples with different sugar levels were presented to each panelist. Panelists were asked to choose the preferred sample according to the sweetness. Eighteen panelists were recruited for this session. The second session consisted of 3 triangle tests and 3 paired comparison tests. In each triangle test, 22 panelists received two commercial Tesco Sea Breeze as the control samples and a treatment sample where some sugar is substituted by glucose. Panelists were asked to taste three samples in each set and to identify the odd sample. In each paired preference tests, panelists received one commercial Tesco Sea Breeze as the control samples and a treatment sample where some sugar is substituted by glucose. They were asked to indicate which sample they preferred.

The third session consisted of 2 triangle tests. Twenty two panelists received two commercial Tesco Sea Breeze as the control samples and a treatment sample where some glucose is substituted by satigum. Panelists were asked to taste three samples in each set and to identify the odd sample. The fourth session required the18 panelists to profile (hedonic scale) five cocktail recipes for three sensory parameters: sweetness, thickness and alcohol bite. A 10-point hedonic scale (1 to 10) was used to determine the specific characteristic of the samples: “1” indicate extreme low intensity, “10” indicate extreme high intensity and “5” for medium intensity.¹⁴ The fifth session involved four sets of paired comparison tests. Twenty two panelists received two samples commercial cocktail formulation and a modified formulation. (Sea Breeze, X on the Beach, Oscar Peach Cocktail and Strawberry Daiquiri). The panelists were asked to choose which one they preferred and why they choose the preferred sample. For all the testing methods, each sample was assigned a three-digit random number. For the results, the number of panelists correctly identified the difference or the number of panelists who preferred a sample would be significant only when the number passed the 95% confident level. Appendix 1, Table 7 shows the minimum numbers of correct judgments to establish significance at various probability levels for paired preference tests and Appendix 1, Table 8 for triangle tests.

RESULTS AND DISCUSSION

Sugar level

Fig 2 shows that 50% of the tasters prefer the highest sugar level (11.88% w/w) and no tasters prefer the lowest sugar level (8.49% w/w), which is the existing Tesco Sea Breeze product sugar level. Investigation of a modified Tesco Sea Breeze formulation containing an increased sugar level was therefore justified based on the observed increase in consumer preference.  Taking into account cost of the formulation and supplier recommendations that glucose in combination with sucrose could increase consumer preference, it was decided to fix the sugar level at 8.92% w/w and investigate glucose addition up to an 11.88 % w/w sweetener level.

Glucose level

The effect of glucose substitution level on consumer ability to differentiate a modified Tesco Sea Breeze cocktail from a control containing no glucose is shown in Table 2. Whilst consumers could not differentiate the substitution of 0.63% w/w of sugar with glucose, glucose substitution at the 1.72% w/w and 2.96% w/w levels were significant and highly significant respectively. Whilst the sample with glucose substitution at the 1.72% w/w level was not preferred, there was a significant preference for the sample with glucose substitution at the 2.96% w/w level (Table 3).  Brown (2000)¹⁵ indicates that glucose is less sweet than sucrose and that it also has a thickening effect in beverages.. Alexander (1998)¹⁶ suggests that sucrose may convert to invert sugar (glucose and fructose), which may cause a taste and sweetness difference. As in the investigation of sugar level, this work on glucose substitution supported further work at the 11.88% w/w sweetener level. As the thickening power of glucose is much less than the other thickening agents such as gums or gelatin, it was decided to extend the investigation to satigum.

Satigum is a hydrocolloid usually added to food formulations to increase their thickness at relatively low concentration.¹⁷. As a result, the thickness of the cocktail should increase when more satigum is added. Amerine and Roessler (1965)¹⁸ reported that there may be some difficulties on satigum addition in assessing bitterness as the flavour and the sweetness may masks bitterness.  The effect of satigum substitution level on consumer ability to differentiate a modified Tesco Sea Breeze cocktail from a control containing 8.92% w/w sugar and 2.96% w/w glucose is shown in Table 4.  Consumers can differentiate the substitution of glucose with as little as 0.05 w/w satigum (p<0.05).  The sweetness, thickness and alcohol bite profiling results on the effect of increasing satigum level on consumer perception are summarized in Table 5.  In terms of sweetness and alcohol bite there are no benefits to increasing satigum level above 0.05% w/w but as expected higher satigum levels did yield better thickness perception results.  Whilst an 0.20% w/w satigum level gave the best thickness perception, the cost-benefits associated with of 0.05w/w satigum level were considered optimal.  As a result of the sugar addition, glucose substitution and satigum substitution work it was decided that the optimal consumer preference would arise if the Tesco Sea Breeze formulation was modified from 8.49% w/w sugar to 8.92%w/w sugar + 2.91% w/w glucose +0.05%w/w satigum.

Optimal formulations

Consumer prefer the modified (8.92%w/w sugar + 2.91% w/w glucose +0.05%w/w satigum) Tesco Sea Breeze (Table 6).  Modifying other commercial cocktail formulations (X on the Beach, Oscar Peach Cocktail and Strawberry Daiquiri) to have 8.92%w/w sugar + 2.91% w/w glucose +0.05%w/w satigum did not significantly alter consumer preference. This suggests that each commercial cocktail product needs to optimized with respect to sweetener levels independently. 

Limitations

This study has some limitations. A larger number of untrained consumers in the panel was desirable. As Hong Kong, local and French students participated in sensory tests, cultural difference may also affect the results. Characterization of the products’ sensory properties would have been better carried out by a trained panel.

CONCLUSION

Consumer preference for a Tesco Sea Breeze product was increased by increasing the sugar level to 11.88% w/w. Additional work at a total sweetener level of 11.88% w/w involving sugar substitution with glucose and satigum proved successful in increasing consumer preference. It is recommended that the commercial partner modify the existing Tesco Sea Breeze recipe to include 8.92%w/w sugar + 2.91% w/w glucose +0.05%w/w satigum. Modifying other commercial cocktail formulations (X on the Beach, Oscar Peach Cocktail and Strawberry Daiquiri) to incorporate 8.92%w/w sugar + 2.91% w/w glucose +0.05%w/w satigum did not significantly alter consumer preference. It is recommended that the commercial partner carry out further sweetener reformulation work on these commercial cocktail product to increase consumer preference.

ACKNOWLEDGEMENTS

The authors would like to thank supervisor, Peter Mitchell for his suggestions and technical ideas, and the commercial partner for their technical assistance which supported the project. The project would not have been completed without their help.

REFERENCES

1.      SaskyCom and PJI-Designs (1999) http://www.sasky.com/saskycom/databases/cocktails/categories/ [Accessed on 11/4/2003]

2.      Cross R, (1996) The Classic Cocktails. Strathearn publishing Ltd. (P.12-16)

3.      Crouch, J. (2002) The Role of Sensory & Consumer Research in the Product Development Cycle: http://www.naffs.org/public/downloads/tech_crouch.ppt

[Accessed on 11/4/2003]

4.      Potter.N and Hotchkiss.H, (1996) Food Science (5^th edition). Chapman & Hall

5.      Murano P.S. (2002) Understanding Food Science and Technology. Thomson publishing (P.367, 374, 424-425, 432-433)

6.      Gould, W. (1993) Total Quality Assurance for the Food Industries. CTI Publications,

7.      Jowitt, R. (1997) The Terminology of Food Texture. J.Texture Stud (P.351- P357)

8.      Guinard, J.X. Mazzucchelli, R. (1996) The sensory perception texture and mouthfeel. Trends in Food Science & Technology Vol. 7. Elsevier Science Ltd.

9.      Bourne M.C. (2002) Food Texture and Viscosity. Concept and Measurement (2^nd edition). Academic Press. (P17-18, 83-84)

10.  Lawless, H. T. & Hildegarde, H. (1998). Sensory Evaluation of food: Principles and Practices. London: Chapman & Hall.

11.  Rosenthal, A.J. (1999) Food Texture. Measurement and Perception. An Aspen Publication Gaithersburg, Maryland. (P. 30 – P.31)

12.  Resurreccion, A. V.A. (1998) Consumer Sensory Testing For Product Development. An Aspen Publication. Gaithersburg, Maryland. (P.11 – P.12)

13.  Stone, H. &. Sidel J.L, (1993) Sensory Evaluation Practice 2^nd Edition.  Academic Press, Inc. (P.11-13, 84-86)

14.  Moskowitz, H.R. & Sidel, J.L. (1971) Magnitude and Hedonic scales of food acceptability. Journal of Food Science. 36 (P.677 – P.680)

15.  Brown, A. (2000) Understanding food. Principles and Preparation. Thomson Learning, Belmont, CA.

16.  Alexander R.J. (1998) Sweetness Nutritive. Practice Guide for the Food Industry. American Association of Cereal Chemists, Inc (P.82 –84)

17.  Clegg, S.M. (1995) Thickeners, gels and gelling, physico-chemical aspects of food processing. Glasgow, Scotland: Blackie Academic & Professional

18.  Amerine, M.A., Roessler, E.B. (1965) Principles of Sensory Evaluation of Food. Academic Press, New York.

Fig.1: Protocol for preparing a laboratory cocktail

Add all ingredients except alcohols

Blending Operation

Cooling in water bath  (room temperature)

Adding alcohols

Bottling

Fig 2: Effect of sugar level on consumer preference for a commercial cocktail

Number of tasters = 18

Table 2: Effect of glucose substitution level on consumer ability to differentiate a modified commercial cocktail from a control containing no glucose

Number of tasters = 22 (12 tasters need to correctly identify difference for significance at 95% confidence level)

n.s. not significant at 95% confidence level

* Significant

** Highly significant

Table 3: Effect of glucose substitution level on consumer preference for a commercial cocktail

Number of tasters = 22 (16 tasters need to prefer a sample for significance at 95% confidence level)

n.s. not significant at 95% confidence level

* Significant

Table 4: Effect of satigum substitution level on consumer ability to differentiate a modified commercial cocktail from a control containing 8.92% w/w sugar and 2.96% w/w glucose

Number of tasters = 18 (10 tasters need to correctly identify difference for significance at 95% confidence level)

* Significant

** Highly significant

Table 5: Effect of satigum level on the sensory profile of a modified commercial cocktail containing 8.92% w/w sugar and 2.91% w/w glucose

Number of tasters =18

Score from 1-10

1 for extreme low intensity   5 for medium intensity      10 for extreme high intensity

Table 6: Effect on consumer preference of modifying the sweetener levels in a range of commercial cocktails 

Number of tasters = 23 (17 tasters need to correctly identify difference for significance at 95% confidence level)

n.s. not significant at 95% confidence level

* Significant

Appendix 1: Statistical tables for the paired comparison and triangle tests

Table 7: Minimum numbers of correct judgments to establish significance at various probability levels for paired preference tests

Table 8: Appendix 2 Minimum numbers of correct judgments to establish significance at various probability levels for triangle tests

Fig. 3 The scoreboard used for triangle tests.

Fig. 4 The scoreboard used for paired-comparison tests

Fig. 5 The scoreboard used for hedonic scales