Asian Journal of Dairy and Food Research, volume 40 issue 4 (december 2021) : 428-433

​Process Optimisation and Quality Evaluation of Passion Fruit and Pineapple based Probiotic Drink

P.M. Meera1, C.L. Sharon1,*, Seeja Thomachan Panjikkaran1, E.R. Aneena1, P.S. Lakshmy1, Saji Gomez1
1Department of Community Science, College of Horticulture, Kerala Agricultural University, Thrissur-680 656, Kerala, India.
Cite article:- Meera P.M., Sharon C.L., Panjikkaran Thomachan Seeja, Aneena E.R., Lakshmy P.S., Gomez Saji (2021). ​Process Optimisation and Quality Evaluation of Passion Fruit and Pineapple based Probiotic Drink . Asian Journal of Dairy and Food Research. 40(4): 428-433. doi: 10.18805/ajdfr.DR-1617.
Background: The functions of food has extended from satisfying hunger and providing nutrients to the body, health maintenance, well being and prevention of diseases. Probiotics are such functional food and when they are incorporated to locally available foods, it helps to improve the nutritional profile and therapeutic value. Hence, the study entitled “Process optimisation and quality evaluation of passion fruit and pineapple probiotic drink” was undertaken with the objective of standardising probiotic fruit drink with passion fruit and pineapple and also to evaluate the nutritional and organoleptic qualities of these developed passion fruit and pineapple probiotic drinks.

Methods: In the present study 5 treatments along with one control with 3 replications were standardized. Passion fruit juice (PFJ) was used as the major ingredient and used in varying proportions starting from 50 to 90 per cent with 10 to 50 per cent of pineapple juice (PJ). The best treatment was selected through sensory evaluation along with control by using a score card with nine point hedonic scale. In the selected treatments optimization for the growth of Lactobacillus acidophilus with regard to substrate concentration, time of incubation, temperature of incubation and inoculum concentration were done. The probiotic drinks and their respective controls were then analysed for their nutrient composition like TSS, titratable acidity, energy and ascorbic acid.

Result: Among the various treatments, highest scores for organoleptic qualities was observed in treatment having 70 per cent passion fruit juice and 30 per cent pineapple juice (T3) with a mean score of 8.52 for overall acceptability. The selected juice was optimized for the growth of Lactobacillus acidophilus and had a viable count of 13.38 log cfu ml-1. The probiotic and non probiotic drinks had TSS content of 12.8 and 13.5° Brix, titratable acidity of 2.28 and 2.03 per cent, energy of 59.32 and 68.96 Kcal and ascorbic acid of 10 and 12.8 mg 100g-1 respectively.
The deeply entwined relationship between food and health benefits has been a fertile field for research since the dawn of the scientific age. This in turn has triggered the development of functional food products. Probiotics are live microbial supplement, which beneficially affect the host by improving the intestinal microbial balance. Addition of probiotics to food provides several health benefits by decreasing the number of pathogenic gastrointestinal microorganisms, reducing the serum cholesterol level, improving the gastrointestinal function, strengthening immune system, protection of proteins and lipids from oxidative damage and anticarcinogenic and antimutagenic effects.
       
The incorporation of probiotics to underutilised fruits can improve their acceptability and market potential. The chief benefits of non-dairy beverages, specifically fruit juices, are their nutritional values, flavor and refreshing quality (Natt and Katyal, 2021). The diverse food mediums of dairy food carriers are the major limitations for the survival of the probiotics whereas the probiotic strains from non-dairy sources are acceptable. Lactobacillus and Bifidobacterium are widely used probiotics which generally regarded as safe (Sugandhi, 2018). Passion fruit (Passiflora edulis Sims.) contains orange coloured pulpy juice with large number of small, hard, dark brown to black pitted seeds. The juice is delicious with good flavour, intense aroma and sweet-acid taste and is well known for its excellent blending quality. The demand for passion fruit juice is increasing not only because of its exotic flavour but also for its high nutritional and medicinal properties (Charan et al., 2017). Yellow passion fruit (Passiflora edulis flavicarpa), which is native to tropical America, is considered as an underutilised fruit crop and considered to be a good source of vitamins, mainly A and C and minerals. Considering these factors, passion fruit can act as a potential matrix for the incorporation of probiotics. If a probiotic product is developed from this fruit, it would definitely attract consumer attention and improve its economic value.
Ripe passion fruit (yellow type) and pineapple were collected from Cashew Research Station and Pineapple Research Station of Kerala Agricultural University, Thrissur, Kerala. Pure cultures of the probiotic strain L. acidophilus MTCC 10307 needed for the study was obtained from Institute of Microbial Technology (IMTECH), Chandigarh. Other ingredients needed for the study were purchased from the local market. The study was conducted at Kerala Agricultural University, Department of Community Science, Vellanikara, Thrissur, during 2018-2020.
 
Standardisation of passion fruit and pineapple drink
 
Passion fruit and pineapple drink was standard with following treatments (Table 1).
 

Table 1: Combinations of passion fruit juice and pineapple juice.


       
For the preparation of passion fruit based drink, the standard procedure of FSSAI (2010) was followed. The quantity of ingredients used for preparation of drink was taken by calculating the acidity and TSS of the sample and then adding other ingredients in accurate quantity to maintain FSSAI limits. Juices were strained and measured. Sugar syrup was prepared by heating appropriate amount of sugar in required amount of water. After cooling, measured quantity of juice was mixed with sugar syrup. It was then pasteurized at 80°C for 20 minutes.
 
Organoleptic evaluation
 
A series of acceptability trials were carried out using simple triangle test at the laboratory level and selected a panel of fifteen judges between the age group of 18-35 years as suggested by Jellinek (1985). The organoleptic evaluation of the drinks were carried out. The drinks were evaluated organoleptically by the judges using a 9 point hedonic scale. The selected drink was taken for further studies.
 
Optimisation of condition for growth of Lactobacillus acidophilus in passion fruit and pineapple drink
 
Optimisation is a process by which numeric function is maximized or minimized, while satisfying all the constraints on the variable. Hence, using L. acidophilus for fermentation, total viable count in the product was maximized while variables like substrate concentration, time and temperature of incubation and quantity of inoculum were kept at acceptable levels.
       
Optimisation of substrate concentration (25 ml, 50 ml and 75 ml), time of incubation (1,2 and 3 hrs), temperature of incubation (37°C, 38°C and 39°C) and inoculum concentration (3 μl, 4 μl and 5 μl of L. acidophilus) was done by enumerating for the total number of viable cells of L. acidophilus after each section.
 
Optimisation of substrate concentration
 
From the selected best combination of passion fruit based drink, 25 ml, 50 ml and 75 ml were measured and was pasteurized at 80°C for 20 minutes and allowed to cool. The pasteurized drink was then inoculated with 4 µl of L. acidophilus culture. The samples were incubated at 37°C for 15 hours. After 15 hrs the samples were enumerated for the viable counts of L. acidophilus.
       
The viability of probiotic organism in fruit drinks were assessed using MRS (De Man Rogosa and Sharpe) medium. One ml of the sample was measured and transferred to a test tube containing 9 ml sterile distilled water (10-1 dilution). This was then serially diluted upto 10-9 dilutions. The microbial enumeration was done by pour plate method using MRS agar and the results are expressed as 109 cfu ml-1.
 
Optimisation of time of incubation
 
The best substrate concentration with maximum number of colonies was taken and pasteurized at 80°C for 20 minutes and allowed to cool. It was then inoculated with 4 µl of L. acidophilus culture. The samples were then incubated at 37°C for 1, 2 and 3 hours. After this, the viability of probiotic organism was enumerated.
 
Optimisation of temperature
 
The passion fruit drink with optimum substrate concentration was selected, pasteurized and then inoculated with 4 µl of the culture and incubated at varying temperatures of 37°C, 38°C and 39°C for optimum time of growth of the organism. The fruit drinks were kept for incubation and then tested for the viability of the L. acidophilus.
 
Optimisation of population of inoculum concentration
 
Each fruit drink combinations with best substrate concentration was pasteurized and then inoculated with 3 μl, 4 μl and 5 μl of L. acidophilus and kept for incubation at optimum temperature for optimum period of time. Fruit drinks were then enumerated for the total number of viable cells of L. acidophilus.
 
Physico chemical analysis of passion fruit and pineapple drink
 
The developed probiotic drink along with its control (non probiotic sample) was assessed for TSS and titratable acidity according to the method of Ranganna (1986) and energy and ascorbic acid of the drinks were also determined according to the standard procedure of Sadasivan and Manickam (1992).
 
Statistical analysis
 
The data obtained were statistically analysed using Kendall’s co efficient of concordance, DMRT and independent t test.
Standardisation and organoleptic evaluation of passion fruit and pineapple drink
 
The passion fruit and pineapple drink were standardised with different proportions of passion fruit juice and pineapple juice. The mean scores and the mean rank scores for organoleptic qualities of passion fruit and pineapple drink are presented in Table 2.
 

Table 2: Mean scores for organoleptic qualities of passion fruit and pineapple drink.


       
The mean scores and mean rank scores for appearance of passion fruit and pineapple drink varied from 8.40 (T5) to 8.93 (T3) and 2.97 to 4.60 respectively. The mean scores for colour varied from 8.00 (T5) to 8.71 (T4). The mean scores for taste varied from 7.44 (T5) to 8.53 (T3). The highest mean rank score for taste obtained was 4.73 for treatment T3. The mean scores for overall acceptability varied from 7.88 (T5) to 8.52 (T3) with mean rank scores in the range of 2.47 to 4.90.
       
Among various treatments, the highest mean scores of 8.93 (appearance), 8.48 (flavour), 8.68 (texture), 8.53 (taste) and 8.52 (overall acceptability) were obtained for T3 (70% passion fruit juice and 30% pineapple juice). Considering highest scores of organoleptic qualities passion fruit and pineapple drink (T3-70% PFJ + 30% PJ) was selected as the best treatment for further studies.
 
Optimisation of condition for growth of Lactobacillus acidophilus in passion fruit and pineapple drink
 
The selected fruit drink along with control was inoculated with the probiotic strain L. acidophilus at various conditions and the optimum growth conditions were concluded from the results. Variables such as substrate concentration, time of incubation, temperature and inoculum concentration were optimised.
       
Table 3, represents the viable count of L. acidophilus with different variables at 109 dilution. 25 ml of the substrate concentration showed maximum growth of the probiotic organism with a colony count of 13.36 log cfu ml-1 comparing to other substrates, 50 ml (13.15 log cfu ml-1) and 75 ml (12.79 log cfu ml-1). The number of colonies in control sample was 13.26, 12.99 and 12.38 log cfu ml-1 in 25, 50 and 75 ml of juice sample respectively. One hour of incubation showed maximum growth (13.36 log cfu/ ml-1) compared to 2 hours (13.14 log cfu ml-1) and 3 hours (12.73 log cfu ml-1) and also that of control sample with viability of 13.25, 12.89 and 12.34 cfu ml-1 for 1, 2 and 3 hours respectively. The best temperature for probiotic growth was 37°C with a colony count of 13.33 log cfu ml-1. Inoculation of 4 µl of culture had maximum growth (13.36 log cfu ml-1) and minimum was 12.50 log cfu ml-1 for 5 µl of inoculation. The number of colonies in control sample was 12.83, 13.27 and 12.44 log cfu ml-1 for 3, 4 and 5 µl of inoculum respectively.
 

Table 3: Viable count of passion fruit and pineapple based probiotic drink with Lactobacillus acidophilus (log cfu ml-1).


 
Physico chemical analysis of probiotic and non probiotic drinks
 
As per Table 4, TSS of the developed probiotic drinks differ significantly with their respective controls. TSS of the probiotic drink was found to be 12.80° Brix where as that of non probiotic drink was 13.50° Brix. Titratable acidity was higher in probiotic drink than non probiotic drink. The control probiotic drink contains 2.03 per cent titratable acidity, whereas the probiotic drink contains 2.28 per cent and there was significant difference in the titratable acidity of probiotic and non probiotic drinks.
 

Table 4: Physico chemical analysis of probiotic and non probiotic drinks.


       
Energy content of the probiotic fruit drink were lower when compared with that of the non probiotic drink. Energy content of non probiotic drink was 68.96 Kcal 100 g-1 whereas that of probiotic drink was 59.32 Kcal 100 g-1. The same situation was observed in the case of ascorbic acid content also. The non probiotic drink contain significantly higher amount of ascorbic acid than the probiotic drink (Table 4).
 
Organoleptic evaluation of passion fruit and pineapple drink
 
In the present study, the mean scores and mean rank scores for appearance of passion fruit based pineapple drink varied from 8.40 (T5) to 8.93 (T3) and 2.97 to 4.60 respectively. The texture of passion fruit based pineapple drink obtained a mean scores from 7.73 (T5) to 8.68 (T3) with mean rank scores in the range of 2.10 to 4.33. The mean scores for texture was the highest in T3 (8.68). The mean scores for colour varied from 8.00 (T5) to 8.71 (T4). The mean scores and mean rank scores for flavour varied from 7.82 (T4) to 8.48 (T3) and 2.93 to 4.40 respectively.  The mean scores for taste varied from 7.44 (T5) to 8.53 (T3). The highest mean rank score for taste obtained was 4.73 for treatment T3. The mean scores for overall acceptability varied from 7.88 (T5) to 8.52 (T3) with mean rank scores in the range of 2.47 to 4.90. This was in accordance with Seale and Sherman (1960) developed blended beverage of passion fruit with orange and pineapple which provided good texture and good flavour to the product and showed good physico chemical and sensory qualities. Shaw and Wilson (1988) prepared passion fruit orange blended nectar concluded that nectar having high proportion of passion fruit have better acceptance. Najumudeen (2015) developed blended fruit syrup of pineapple and passion fruit and reported that product were bright in colour and was highly acceptable by the consumers.
       
Among various treatments in the present study, the highest mean scores of 8.93 (appearance), 8.48 (flavour), 8.53 (taste), 8.68 (texture) and 8.52 (overall acceptability) were obtained for T3 (70% passion fruit juice and 30% pineapple juice). Considering highest scores of organoleptic qualities passion fruit based pineapple drink (T3-70% PFJ + 30% PJ) was selected as the best treatment for further studies.
 
Optimisation of condition for growth of Lactobacillus acidophilus in passion fruit and pineapple drink
 
Fruit juice act as a good medium for probiotic organism growth and also can maintain a  minimum therapeutic level 109 cfu/g or ml (WHO, 2001). According to Manasi et al., (2013) the viability of Lactobacillus acidophilus decreased upon refrigerated storage of probiotic pineapple juice. The initial count 3.8×107 cfu ml-1 diminished to 1.8×107 cfu ml-1, however the count doesn’t go below the minimum level. During storage at 30±1°C, the count expanded to 9.5×108 (in 48 hrs) and afterwards declined to 2.9×107 cfu ml-1 after 120 hrs. A probiotic beverage with whey and pineapple juice was prepared by Shukla et al., (2013) at a ratio of 65:35 and revealed that a good quality probiotic drink can be developed using one per cent of inoculum of Lactobacillus acidophilus which can be stored for 24 days at 5±1°C and 48 hrs at 30±1°C. Adebayotayo and Akpeji (2016) developed probiotic pineapple juice, were the juice supported the viability of the organism, lactic acid production, vitamin C production and antagonistic potential of the probiotic bacteria. The lactic acid bacteria were viable throughout the storage (1.05 to 1.10×109 cfu ml-1) and there was no difference in taste, colour, aroma or appearance of the final product after a storage period of four weeks. Gallina et al., (2019) developed and characterised probiotic fermented smoothie beverage and concluded that the viable count of the probiotic organism of passion fruit and mango blend after 1, 13 and 30 days of storage was 7, 7.5 and 6.5 log cfu ml-1 respectively at a temperature of 8±2°C. Nguyen et al., (2019) investigated that without any supplements Lactobacillus and Bifidobacterium were able to grow well in pineapple juice and acts itself as a matrix for the propagation of probiotic bacteria. Monteiro et al., (2020), suggested that passion fruit pulp act as a good medium for probiotic culture, when fermented at a temperature of 30°C.
       
According to Shukla et al., (2013), who developed whey based probiotic pineapple beverage, did not show much difference in sensory evaluation and also concluded that the main descriptors that characterised the probiotic product were acidity and sweetness. The mean score for overall acceptability of whey-pineapple juice blend was 8.87. Flavour and taste of the product was found to be enhanced due to probiotication. This may be due to the process of fermentation occurred in the beverage
 
Physico chemical analysis of passion fruit and pineapple drink
 
During probiotic fermentation, the organism convert glucose to lactic acid. This is responsible for the decrease in pH of the product. During fermentation, the probiotic organism produces lactic acid by hydrolyzing starch. This reduces the TSS content and starch in probiotic samples. This metabolic activity convert starch to fermentable simple sugars which is used by probiotic organisms (Adams et al., 2008). Yan-li (2011) produced wine with combination of pawpaw and passion fruit and the pH was estimated as 4.0. Fernandes et al., (2011) concluded that upon pasteurisation of passion fruit juice, there is increase in titrable acidity (3.06 g 100 ml-1) were as the homogenised juice have 2.83 g 100 ml-1. The titrable acidity of wine produced from mixed juice of passion fruit, mango and pineapple was 1.4 per cent after fermentation and TSS was 20° Brix (Nzbuheraheza and Nyiramugwera, 2014). Lactobacillus spp. is more effective in reducing pH than yeasts and other microbes (Gautam and Sharma, 2014). The reduction may be due to the utilisation of sugars for the metabolic activity of probiotic LAB in the probiotic juice samples. Similar observation was reported by Kumar et al., (2011), in fruit juice with Lactobacillus casei. There was reduction in TSS content of probiotic pineapple juice formulated by Adebayo Tayo and Akpeji (2016) from 15.28 to 12.68° Brix after storage of 4 weeks.
       
Stanton et al., (2005) reported that both genera Lactobacillus and Bifidobacterium were reported to have high requirements of free amino acids, peptides, vitamins and fermentable carbohydrates for their growth and development. Lactobacillus and Bifidobacterium strains grow well in pineapple juice meaning this matrix in itself was a suitable medium for propagation of probiotic bacteria. Pineapple juice acts as a good matrix for probiotic growth without any supplements of nutrients. Nazarudeen (2010) suggested that, increased moisture content reduces the nutritive factors such as fat and carbohydrate, thereby reducing the energy value. Shukla et al., (2013) reported that reduction in ascorbic acid content of probiotic drinks were may be due to pasteurisation of juice and exposure to light. The ascorbic acid content in RTS drink prepared by blending juices of passion fruit and cashew apple in different ratios such as 25:75, 50:50, 25:75 + ginger drops and 50:50 + ginger drops was 80.26 mg 100 g-1, 79.73 mg 100 g-1, 76.39 mg 100 g-1 and 79.29 mg 100 g-1 respectively (Sobhana et al., 2011).
It can be concluded that passion fruit and pineapple are good option for the development of probiotic drinks. This study was targeted to formulate a probiotic passion fruit and pineapple drink using Lactobacillus acidophilus as the probiotic bacterial culture. Good quality probiotic drink was prepared by using a 70:30 blend of passion fruit juice and pineapple juice with good acceptability, nutritional qualities with a viable count of 13.38 log cfu/ ml.
The author would like to acknowledge Kerala Agricultural University, Thrissur- 680 656 for providing fund for the conduct of the study.

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