Comprehensive Evaluations of Physicochemical Characteristics and Sensory Acceptance of Selected Fruits, Almond and Dark Chocolate Incorporated Yogurt

The research aimed to formulate a yogurt mix by combining with natural flavored selected fruits (papaya, apple, banana and mango), almond and dark chocolate for enriched nutritional value and taste. For quality assessment of the yogurt mixture, physicochemical, phytochemical, nutritional and sensory properties were considered. The experimental data of yogurt mix were fitted to 14 models where plain yogurt was used as a control and concomitant 10% and 20% yogurt supplements were considered with the mentioned ingredients. The comparative results of all the formulations revealed notable enrichment in yogurt samples compared to the control. Moreover, a significant reduction in lipid content and ______________________________________ 1Department of Biochemistry and Biotechnology, University of Science and Technology Chittagong, Chattogram – 4202, Bangladesh. 2Faculty of Biomedical Engineering, Universiti Teknologi Malaysia, Malaysia. *shimunath@gmail.com https://orcid.org/0000-0002-4478-9379 This article is published under the terms of the Creative Commons Attribution 4.0 International License which permits unrestricted use, distribution and reproduction in any medium provided the original author and source are credited. pH of the enriched yogurts were observed. In contrast, the fortified yogurt exhibited higher carbohydrate, protein, phenolic and flavonoid contents than the control. Furthermore, the Ash content of all yogurt formulations excluding the yogurt-banana mix was found to be lower than the control and total soluble solids (TSS) were observed to be increased ranging from 10.81 to 15.30g per 100g of fortified yogurt. Nevertheless, the yogurt fusions conclude that almond-yogurt (AlY20) and mixed-fruits yogurt (MxY20) are the best suitable mix in terms of their acceptability, phytochemical and physicochemical composition.


INTRODUCTION
Nowadays, healthy habits and nutrition consciousness of consumers have resulted in rising demand for fruits containing high flavonoid content utilizing fortification. Yogurt is a coagulated milk product resulting from the fermentation of lactose in milk by Lactobacillus bulgaricus and Streptococcus thermphilus (Corrieu et al., 2016) (Eslampour et al., 2020;Yada et al., 2013). In another study, dark chocolates are confirmed as an excellent source of magnesium and iron and chocolate containing 90% cocoa is believed to be a good source of zinc and selenium that is important for our immune system (Cinquanta et al., 2016).

Raw Materials
The milk samples were collected from the local dairy farm. The selected fruits i.e. papaya, apple, banana and mango for supplementation into yogurt were purchased from the local market.
Almond and dark chocolate were also collected from the local market of Chittagong Zone, Bangladesh.

Processing of the Fruit Pulp
To prepare fruit pulp for adding into yogurt, selected fruits were processed using the standard method with slight modification. At first, the fruits were sorted according to their visual quality. Then the fruits were rinsed in warm water. Separate the pulp from the peel. The seeds and the peel were discarded. Finally, the pulps were blended and pasteurized at 70°C for 10 mins intended to eliminate pathogens and to extend its shelf life.
Likewise, almond and dark chocolate were also blended for supplementation purposes.

Formulation of Fortified Yogurt
Yogurt formulation was carried out in the laboratory of the Department proportions (10% and 20%) of each ingredient was added into milk. Table 1 shows   (1959) method.

Phytochemical Composition Analysis
The presence of phenolic content was determined by slightly modifying

Statistical Analysis
All analytical studies were done using three replicates to prove the reproducibility of the analysis.
Analyzed data were represented as mean±standard deviations. Statistical significance of data was evaluated by one-way ANOVA ( * indicates p < 0.05 which is statistically significant).

RESULTS AND DISCUSSION
In the light of low-cost availability and nutritional value of fruits, almond and dark chocolate, the combinatory effect of these ingredients with yogurt were studied separately at two different percentages mainly 10% and 20%.

Sensory Analysis
The sensory evaluation of fortified   In conclusion, MxY20 and almond-yogurt (AlY20) were found to be more acceptable compared to other fruits enriched yogurt and control plain yogurt. It is interesting to note that yogurt enriched with dark chocolate (CY10 and CY20) was the least acceptable among all other types of yogurts for the reason that dark chocolate contains more than 80% cocoa which makes it bitter-taste.
Surprisingly, a few participants preferred to have plain yogurt because of the well-known flavor and texture of plain yogurt.

Physico-Chemical Analysis
The aim was to identify the effect of fruit-supplement in yogurt on the pH of the yogurt. The comparative performances on pH are shown in Table   3. The analysis exhibited a significant decrease in pH for all other fortified yogurt ranging from 4.87±0.06 to 5.47±0.06 against the control (5.80±0.00).
The lowest pH value was found to be 4.87±0.06 in apple enriched yogurt (AY20) as apple is moderately acidic in contrast to other fruits. Similar findings    As Table 4  As regard protein content, it can be seen that a positive correlation exists between added ingredients and improvement in protein content.  et al. (2015).   (1)