Quality Characteristics and Sensory Profile of Flavoured Yogurt Enriched with Banana and Pineapple

Quality Characteristics and Sensory Profile of Flavoured Yogurt Enriched with Banana and Pineapple

Okoroafor, Clara Nneka*, Obinwa, Ezinne Prisca 

Department of Human Nutrition and Dietetics, Faculty of life Science, Ambrose Alli University Ekpoma, Edo State, Nigeria

*Corresponding Author

DOI: https://doi.org/10.51244/IJRSI.2025.12010064

Received: 17 January 2025; Accepted: 22 January 2025; Published: 18 February 2025

ABSTRACT

The purpose of this study was to enhance nutritional and consumer wellbeing through a holistic approach of evaluating the proximate and sensory attribute of flavoured yogurt enriched with banana (Musa acuminata) and pineapple (Ananas comosus) in order to meet the increasing demand for functional meals that improve nutritional qualities and overall health. To assess the yogurt samples proximate composition and sensory qualities, the study used an experimental design. A defined recipe that included 5% fruit with 1.5 litres of water, sugar, gelatin, and starter culture were used to produce the yogurt. In order to ascertain the level of moisture, ash, fat, protein, and carbohydrates, proximate analysis was carried out using AOAC procedures. A panel of 40 judges used a 9-point hedonic scale to evaluate the flavour, aroma, texture, appearance, and overall acceptability of the products. The results showed that attribute of pineapple flavoured yoghurt after fermentation had the overall acceptability of 6.2 followed by banana flavoured yoghurt after fermentation 6.1. Addition of pineapple and banana to the yoghurt production enhanced both its nutritional and sensory qualities, which increased its consumer appeal. The results show how local fruits can be used to make yoghurt, which can lead to healthier, more nutrient-dense products that satisfy consumer preferences and correct nutritional inadequacies. The development of functional dairy products that can enhance health outcomes for groups with dietary problems is made easier by this research. It is advised that more research be done to determine the long-term health advantages of these flavoured yoghurts and whether larger markets will accept them.

Keywords:  Flavoured yoghurt, Nutritional enhancement, Sensory evaluation, Banana, Pineapple, Consumer well-being

INTRODUCTION

Developing functional foods that support consumer well-being and nutrition has garnered increasing attention in recent years. The need for nutrition to support overall wellness and health has been highlighted by the rising incidence of diet-related diseases like obesity, diabetes, and cardiovascular ailments throughout the world. Nearly 2 billion people worldwide suffer from various forms of malnutrition, according to the World Health Organization (WHO, 2021). This highlights the critical need for novel dietary solutions that combine nutritious components with sensory appeal. The term “yoghurt” is derived from the Turkish word “yogurmak,” which means to coagulate, curdle, or thicken (Dahiru et al., 2022).  Yoghurt is a smooth, fermented milk product that evolved some centuries ago through the growth of streptococcus thermophilus and lactobacillus bulgaricus which ferment the milk sugar (lactose) to produce lactic acid. These microorganisms convert milk lactose into lactic acid and make the milk sour (Nagaoka, 2019).

The reliance on staple crops, combined with limited awareness of dietary diversity, presents a significant problem. Many existing yoghurt products in the Nigerian market do not adequately leverage the nutritional potential of local crops, leading to missed opportunities for enhancing health outcomes. This study focuses on the potential of enriching yoghurt—a popular dairy product—by incorporating two locally available fruits: banana (Musa acuminata) and pineapple (Ananas comosus).

Bioactive substances found in bananas, such as phytosterols, biogenic amines, carotenoids, and phenolics, have a good impact on human health and wellbeing and efficiently shield the body against oxidative stressors (Singh et al., 2016). It contains vitamins A, B6, C and D as well as potassium (that prevents muscle spasms). It aids constipation and presents a good relief for diarrhoea. Its main benefits include mood improvement, weight loss and promotion of the human muscles and bones (Amao, 2017).

Similarly, Pineapple contains considerable amounts of bioactive compounds, dietary fiber, minerals, and nutrients. In addition, pineapple has been proven to have various health benefits including anti-inflammatory, antioxidant activity, monitoring nervous system function, and healing bowel movement (Ali et al., 2020). Recent studies have highlighted the potential health benefits of pineapples, including their antioxidant properties, which may help reduce oxidative stress and lower the risk of chronic diseases (Seenak et al., 2021).

This research aims to improve the product’s nutritional profile and sensory qualities (taste, aroma, and texture) by fortifying yoghurt with these fruits. This study aims to improve consumer well-being by promoting better eating choices through a holistic approach that combines sensory evaluation with proximate composition analysis. The findings help create novel food products that satisfy customer demands and tastes, improving health outcomes for a group that faces serious nutritional difficulties.

MATERIALS AND METHODS

Materials

Skim powdered milk, banana, pineapple, gelatin, starter culture (Lactobacillus spp.) and granulated sugar were obtained from Eke-ukwu market in Owerri Municipal Council of Imo State, Nigeria.

Equipment used

Petri-dishes, test tubes, pipettes, flasks and bottles, potato Dextrose Agar, Nutrient Agar, incubator, refrigerator, Kjeldahl distillation apparatus, volumetric flask, dessicator, oven, Whatman filter paper, Soxhlet flux flask, reflux flask, Binaton electric blender, Jenway electronic spectrophotometer, electro thermal heater, extracting flask, aluminum foil, conical flask, non-absorbent coton wool, Bunsen burner, Gallenkamp electronic colony counter, weighing balance, 9-point hedonic scale.

Chemical used

Selenium catalyst, concentrated H₂SO₄, NaOH solution, Petroleum Ether, sulphuric acid, Dilute HCL, Vanado-Mohybdate coloured reagent, EDTA, Solochrome Dark Blue colour, Ca and Mg complexities, Ammonia Buffer, mentholated spirit.

Methods

Sample processing

The banana and pineapple fruits were washed, peeled and sliced into small sizes, and further blended using Binaton electric blender. The production of flavoured yoghurt was conducted in the food processing laboratory of the Department of Food Science and technology, Federal University of technology, Owerri Imo State and National Root Crop Research Institute Umudike, Abia State. The laboratory analyses of the yoghurt samples were carried out at the same locations.

Sample preparation

Skim powdered milk of 400g was reconstituted with 1.5L. of water and heated to 80⁰C for 15 minutes for pasteurization and then allowed to cool to 42-45⁰C before inoculation with starter culture. The sample were divided into five portions, plain (control), pineapple flavoured before fermentation (PFBF), banana flavoured before fermentation (BFBF), banana flavoured after fermentation (BFAF), pineapple flavoured after fermentation (PFAF). The samples were incubated at 35⁰C for 10-12 hours (overnight) until a pH of 4.3 – 4.5 was obtained. The yoghurt samples were allowed to cool at 6⁰C in the refrigerator before they were analyzed.

Determination of Proximate Composition 

The proximate composition of the samples from each treatment sample was done according to the method stated by the Association of Official Analytical Chemists (AOAC, 2005). The samples from each treatment were rinsed and ground in a Moulinex Blender. The ground samples were used for proximate content determination.

Total solids

The total solid of the yoghurt sample was determined using gravimetric method described by AOAC (2016). Five grams of the sample was collected and subjected to dryness by placing it into an oven at 105⁰C for four hours. It was heated until constant weight was obtained

% total solid = w₂ – w₁   x 100

                         W₁ – w_{2         1}

Moisture content

The AOAC (2016) method was used to determine the moisture content of each sample. Each sample was weighed in a moisture container and dried in an oven at 150°C for three hours, until the difference between consecutive weights was less than 0.001g. The moisture content was determined using the following formula after chilling in a desiccator: moisture (%) = (w3 – w1) / (w2 – w1) x 100, where w1 is the empty can’s initial weight, w2 is the can’s weight including sample before drying, and w3 is the weight after drying.

Ash content

AOAC (2016) method was used to determine the ash content of the samples. By heating two grams in a ceramic crucible at 550°C for three hours, the samples were then weighed and the formula, ash (%) = (w2 – w1) / (weight of sample) x 100, was applied. Here, w1 stands for the weight of the empty crucible and w2 for the weight of the crucible plus ash.

Fat content

The AOAC (2016) instruction was used. A Soxhlet extractor was used to measure the fat content of the samples. They were wrapped in filter paper and extracted with petroleum ether for four hours. The percentage of fat was computed by drying and weighing the extracted fat, and then dividing the result by the sample weight.

Crude protein

The Kjedahl method was described by AOAC (2016). Kjeldahl catalyst (selenium tablets) and 20 milliliters of concentrated sulfuric acid were used to digest one gram of material for eight hours. % protein = % nitrogen x conversion factor (6.25) was the formula used to determine the protein content.

Carbohydrate content

AOAC (2016) formula was adopted to determine the carbohydrate content. The sample’s carbohydrate content was determined by difference.

% carbohydrate = 100% – a+b+c+d+e (ie protein + fat + fiber + ash + moisture content).

Sensory evaluation

The product samples were evaluated using hedonic method for sensory characteristics and overall acceptability by a panel of 40 judges selected randomly. They were served coded samples of yoghurt and asked to compare the samples by testing for taste, aroma, texture, appearance and overall acceptability. All tests were performed and rated on a 9 – point hedonic scale described by Iwe (2014).

Statistical analysis

The data obtained from laboratory analysis and sensory evaluation were analyzed using analysis of variance (ANOVA), according to the method of Iwe (2014) to determine the variance ratio. Sample means were compared to determine treatment effects. The least significant difference was calculated at 95% level of significance using Turkey test (T- test).

RESULTS AND DISCUSSION

Proximate composition of flavoured yoghurts is shown in table 2. The nutritional composition of various yoghurt samples, including plain and flavoured varieties, shows notable differences in their moisture, ash, protein, fat, total solids (TS), and carbohydrate content. The analysis presents a comparative overview, highlighting the variations among different yogurt formulations.

Moisture content

Significant variation (p<0.05) in moisture content in fruit yoghurt increased with the increase of fruit pulp except the addition of banana pulp. The highest (89.98%) and the lowest (84.58%) moisture content were observed in pineapple flavour after fermentation (PFAF) and banana flavour before fermentation (BFAF) samples respectively. whereas, the moisture content of the pineapple flavour before fermentation (PFBF) was recorded to be 89.80%, that of the banana flavour after fermentation (BFAF) increased to (84.60%). This implies that the moisture content in banana yoghurt decrease with fermentation of pulp. Also fermentation increased the moisture content of pineapple pulp. This result was in agreement with the findings observed by Tarakci and Kucukoner (2003) physical, chemical. Microbiological and sensory characteristics of some fruits flavoured yoghurt.

Ash content

It reflects the mineral composition of the yoghurt. The samples range from 0.45% (PFAF) to 0.80% (BFAF), with BFAF showing the highest mineral concentration. The differences in ash content might be attributed to variations in the ingredients and processing methods used in each yoghurt formulation.

Protein content

Protein levels are relatively similar across the samples, with values ranging from 8.60% (PFAF) to 8.76% (BFBF). The protein content is critical for the nutritional profile of yoghurt, providing essential amino acids and contributing to muscle repair and overall health. The slight variation may indicate differences in the milk sources or the addition of protein-rich ingredients in specific formulations.

Fat content

This is one of the most important quality attributes of yoghurt. It depends on milk quality, amount of fruit pulp, fruit variety and other treatments. Addition of fruit pulps had significantly (p<0.05) effect on the fat content of fruit yoghurt but is however affected considerably by fermentation.  The highest fat (3.69%) was found in BFBF sample among the two fruit yoghurt samples. This implies that the fat content in fruit yoghurt decreases gradually with fermentation of the pulp content.

Total solids (TS)

Total solids (TS) content varies slightly among the samples, with values between 15.48% (PFAF) and 17.26% (BFAF). Higher TS levels indicate a thicker yoghurt, which can enhance consumer satisfaction.

Carbohydrate content

It also plays a vital role, with the samples ranging from 15.48% (PFAF) to 25.42% (BFAF). The carbohydrate content is predominantly derived from lactose, which impacts the yogurt’s sweetness and texture.

Sensory evaluation

According to the table’s results of the sensory evaluation, pineapple-flavored yogurt before fermentation (PFBF) received the highest ratings for taste (6.4), aroma (6.1), and overall acceptability (6.2). This implies that the flavor profile and consumer appeal were improved by the inclusion of pineapple before fermentation. Plain and banana-flavored yogurts had lower ratings, particularly for taste and aroma, which suggests that consumers are not as fond of them. With very little variations, texture, and appearance were more consistent within the samples. In terms of sensory qualities, pineapple-flavoured yoghurts especially those flavoured before fermentation were generally the most preferred.

CONCLUSION

The study concluded that the nutritional quality of the plain yoghurt was improved by the addition of banana and pineapple. This implies that the therapeutic potency of yoghurt could be improved because consumption of foods with high vitamin A and C can aid in combating deficiency diseases like scurvy and night blindness. The sensory attributes (taste, aroma, texture, appearance and overall acceptability) evaluated revealed appreciable degree of acceptance by consumers thereby increasing varieties of yoghurt in the market. Additionally, the most nutrient-dense and aesthetically pleasing choice was pineapple-flavored yogurt added before fermentation, or PFBF. It was the best product for marketability and consumer preference since it had the best taste, aroma, and nutritional qualities combined with excellent acceptability.

RECOMMENDATIONS

• Promote yoghurt with pineapple flavour added before to fermentation as the most consumer-friendly choice.
• Enhance the flavour intensity and aroma of banana-flavored yoghurt to increase its appeal.
• Widely consumed fruits may be incorporated in yoghurt formulation before or after fermentation rather than adding artificial flavorings.

Fig 1: Flow chart for the production of plain yoghurt

Fig 2: Flow chart for the production of flavoured yoghurt after fermentation

Fig 3: Flow chart for the production of flavoured yoghurt before fermentation

Fig 4: Flow chart for the production of banana pulp

Fig 5: Flow chart for the production of pineapple pulp

Table 1: Recipe for yoghurt production

Ingredients	Ply	BFBF	PFBF	PFAF	PFAF
Skim milk	100g	100g	100g	100g	100g
Water	1.5L	1.5L	1.5L	1.5L	1.5L
Starter culture	2g	2g	2g	2g	2g
Sugar	4g	4g	4g	4g	4g
Gelatin	4g	4g	4g	4g	4g
Fruits		5%	5%	5%	5%

BFBF: Banana flavored before fermentation.

PFBF: Pineapple flavored before fermentation.

BFAF: Banana flavored after fermentation.

PFAF: Pineapple flavored after fermentation.

PLY: Plain yoghurt

Table 2: Nutritional composition of plain and flavoured yoghurts

Samples	Moisture (%)	Ash (%)	Protein (%)	Fat (%)	TS (%)	Carbohydrate
BFBF	84.60±0.0c	0.76±0.1 a	8.76±0.0 a	3.69±0.0 a	17.19±0.0 a	25.40±0.0ab
BFAF	84.58± 0.0c	0.80±0.02 a	8.73±0.0a	3.63±0.0 a	17.26±0.0a	25.42±0.0 ab
PFBF	89.80±0.0b	0.70±0.01ab	8.71±0.0ab	3.68±0.0a	17.17±0,0b	25.02±0.0a
PFAF	89.98±0.0bb	0.68±0.02ab	8.60±0.0bc	3.57±0.0b	17.11±0.0bc	25.20±0.0a
PLY	85.74±1.40bd	0.45±0.01ac	10.81±2.1bd	1.23±0.11c	16.10±0.0bd	15.48±0.32ac

Values are means of triplicate analysis and standard deviation means with different superscripts in the same column are significantly different

Key: TS – Total solids: BFBF – Banana flavoured before fermentation: BFAF: Banana flavoured after fermentation: PFBF: Pineapple flavoured before fermentation: PFAF: Pineapple flavoured after fermentation: PLY: plain yoghurt.

Table 3: Sensory evaluation of flavoured yoghurt before and after fermentation

Attributes	Taste	Aroma	Texture	Appearance	Overall acceptability
Plain	5.4b	5.8b	5.6ab	5.8ab	5.7 b
BFBF	5.1b	5.7b	5.5ab	5.5 ab	5.7b
PFBF	6.4a	6.1 a	5.5ab	5.5ab	6.2a
BFAF	6.2a	5.9 ab	5.5ab	5.7ab	6.1a
PFAF	5.0b	5.6b	5.7ab	5.2bc	5.9ab

Values are means of triplicate analysis and standard deviation means with different superscripts in the same column are significantly different

Key: TS – Total solids: BFBF – Banana flavoured before fermentation: BFAF: Banana flavoured after fermentation: PFBF: Pineapple flavoured before fermentation: PFAF: Pineapple flavoured after fermentation: PLY: plain yoghurt.

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