May. 2014. Vol. 2, No.1

ISSN 2311 -2476

International Journal of Research In Agriculture and Food Sciences © 2013 - 2014 IJRAFS & K.A.J. All rights reserved http://www.ijsk.org/ijrafs.html

QUALITY ATTRIBUTES OF FRUIT JUICES MADE FROM BLENDS OF INDIGENOUS FRUIT (AFRICAN STAR APPLE) WITH CONVENTIONAL FRUIT (PAPAYA) A.O. DAUDA Department Of Food Technology, University Of Ibadan, Ibadan, Nigeria, West Africa, Africa.

ABSTRACT The quality attributes and consumer acceptability of juice blends made from African Star Apple (Chrysophyllum albidum) and papaya (Carica papaya) were investigated using a panel of about twenty eight (28) people. The chemical and sensory properties of the juices were determined. The fresh juice made from African Star Apple fruits had 23 0B (soluble solids) and pH 3.40 while that made from papaya fruits had 11.50B (soluble solids) and pH of 4.50. Physico-chemical properties such as pH, total titratable acidity (TTA), vitamin C, colour, viscosity were determined for each blend. All the physical and chemical properties with the exception of ascorbic acid were within acceptable range. The low value of ascorbic acid could be attributed to factors such as light, oxygen, heat, pH which ascorbic acid is sensitive to. The sensory evaluation by twenty-eight assessors indicated that treatment with 40% African Star Apple juice blended with 60% papaya juice and that of 30% African Star Apple juice blended with 70% papaya were most preferred. There were significant differences in the colour, flavour and general acceptability but not significant for taste. Pure African Star Apple juice was the least preferred. Keywords:

African Star Apple Juice, Papaya Juice, Physico-Chemical, Blending ratios, Shelf-life.

also represent a similar waste of human effort, farm inputs, livelihood, investments and scarce resources such as water. It implies that fruits, most often, do not attain their maximum market value thereby leading to less return to the grower as an individual and economic loss to the nation as a whole. Processing of fruits and vegetables to juice and other valuable products are the ways abundant fruits and vegetables can be utilized to reduced wastage and bring economic returns to farmers.

INTRODUCTION In our nation Nigeria, many organizations from both the governmental and non-governmental sectors are actively promoting the processing of fruits and vegetables. Fruits and vegetables are among the most important foods of mankind as they are not only nutritive but are also indispensable for the maintenance of health (Wong et al, 2003). They are valued for their attractive appearance, characteristics flavour and taste. They play important roles in the diet of most people in the tropics, providing essential minerals and vitamins and adding colour, flavour and variety to monotonous diet (Ragaert et al., 2004).

The fruits generally used for making juice are orange, grape, apple, lemon, mango, pineapple etc. Many of the tropical fruits and some other fruits have not been utilized in the area of fruit juice. Pawpaw (Carica papaya) is widely consumed fresh and has found application throughout the world in various food products. It is used to make soft drinks, nectar, jam fruit leather and soup as well as flavour ingredient but its utilization as juice has received less attention.

Fruits and vegetables are abundant during their various seasons, with over 50% lost to wastage due to deterioration under tropical conditions due to the high ambient temperatures and humidities, pest and disease infestations, poor handling and storage facilities (Pantastico, 1975; Levi et al; 1983; Aworh and Olorunda, 1988). In 1998, World Resources Institute reported that not only are losses clearly a waste of food, but they

Indigenous tropical fruits for example, African Star Apple (Chrysophyllum albidum) are often left unexploited and are allowed to waste

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May. 2014. Vol. 2, No.1

ISSN 2311 -2476

International Journal of Research In Agriculture and Food Sciences © 2013 - 2014 IJRAFS & K.A.J. All rights reserved http://www.ijsk.org/ijrafs.html

due to their excess supply in their season. Due to this, rural producers are often forced to give away their produce or allow them to rot away due to the fact that the fruit has very short life span after ripening. To prevent this loss, processing into their valued products to be sold in urban areas is of importance. Processing of the gluts from these fruits has received less attention until recently where research work on the suitability of this fruit into food preserves, drinks is being looked into. The present study was carried out to investigate the production of juice from Chrysophyllum albidum, juice production from Carica papaya, evaluate some of the chemical and physical properties of the juices, blending of the juices together in various ratios and investigating the consumer acceptability of the juice products.

1.2 Blending of juices. The puree from the papaya was blended with extracted juice from the African Star Apple (“Agbalumo”) in different ratios ranging from 70%: 30% to 30%: 70% respectively before pasteurization. 1.3 Shelf life study. The shelf life of the blended juice is studied in terms of sensory and physico-chemical quality. 1.4 Sensory analysis. Sensory evaluation of the juices was judged for colour, taste, flavour and general acceptability on a nine point hedonic scale, varying from “dislike extremely” (score 1) to “like extremely” (score 9) was used according to Stone and Sidel (1992). An informal panel of twenty eight (28) untrained assessors carried out the acceptance test. Samples were served in transparent glass cups. The juices were also ranked for preference.

MATERIALS AND METHODS 1.1 Procurement and processing of juices from African Star Apple and Papaya. African Star Apple (Chrysophyllum albidum) and pawpaw (Carica papaya) were collected from a local farm at Ajibode village in Ibadan. Fresh, juicy, good quality African Star Apple and Papaya were sorted for processing. The fruits were washed thoroughly under tap water followed by distilled water to remove foreign materials. Juice was extracted from the papaya and filtered through sterilized muslin cloth.

1.5 Physico-chemical analysis. pH of the juices were measured using electrode and potent meter standardized with buffer solution of pH 9.18 and 4.01 at temperature of 250C after 10g of the juice had been weighted into a clean Erlenmeyer. Total Soluble Solids (TSS) for the juices was determined in Degree Brix using a Hand Refractometer. Viscosity of the juice in Centipoise was determined using Baroid Rheometer. Total titrable acidity of the juice was determined by titrating 10ml of the juice with 0.1N NaoH with slight modification. 1ml of the sample was diluted into 100ml volumetric flask and one drop 1% phenolphthalein was added and shaked properly to give a pink colour with the result expressed as percentage citric acid. Ascorbic acid content of the juice in mg/100g was determined using Phenol, 0.4% oxalic acid and dye method. The colour/browning effect of the juice was determined by measuring absorbance at 420nm on the Spectrophotometer. It was carried out in triplicate.

African Star Apple fruits commonly called “Agbalumo” in the Yoruba speaking area of Nigeria that had been properly washed were hand peeled using kitchen knives. The pulp was separated from the seeds and peels. The pulps to be used for juice production were reduced in size to increase the rate of extraction of liquid components and also for easy blending. The blended pulp was extracted using sterilized white muslin cloth. Juice obtained was cloudy as some suspended particles were present. The juice was further filtered using Keiselghur. The clearer juice was stored for further use. RESULTS AND DISCUSSION

Table 1: Result of Hedonic Scale Test for Juice Blends _______________________________________________________________________ Juice Sample

Colour

Taste

Flavour

General Acceptability__

70% AJ + 30% PJ

4.25c

3.72a

3.96b

3.68b

60% AJ + 40% PJ

4.32b

3.82a

3.68c

3.36c

50% AJ + 50% PJ

4.11d

3.46a

3.54c

3.32c

40% AJ + 60% PJ

3.68e

3.36a

3.36c

3.14c

30% AJ + 70% PJ

3.75e

3.50a

3.57c

3.29c

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May. 2014. Vol. 2, No.1

ISSN 2311 -2476

International Journal of Research In Agriculture and Food Sciences © 2013 - 2014 IJRAFS & K.A.J. All rights reserved http://www.ijsk.org/ijrafs.html

Pure AJ

5.68a

AJ = “Agbalumo” Juice

3.68a

4.56a

4.32a________________

PJ = Papaya Juice

Means for each attributes followed by the same letter are not significantly different at 5% level by Tukey.

Table 2: Results of Ranking Juice Blends ___________________________ Treatment

Scores

70% AJ + 30% PJ

45c

60% AJ + 40% PJ

36b

50% AJ + 50% PJ

27b

40% AJ + 60% PJ

12a

30% AJ + 70% PJ

15a

Pure AJ

54c

AJ = “Agbalumo” Juice, PJ = Papaya Juice 19 – 44 at 5% significant level 23 – 40 at 1% significant level.

Table 3: Chemical Composition of Juice Blends ________________________________________ Parameters Sample TSS AA

TTA

pH_

100% AJ

23

12.00

1.08

3.40

100% PJ

11.5 10.60

0.13

4.50

70% AJ + 30% PJ

18

15.58

0.60

3.70

60% AJ + 40% PJ

18

15.90

0.50

3.60

50% AJ + 50% PJ

17.5 9.36

0.43

3.60

40% AJ + 60% PJ

15.3 12.25

0.33

3.55

30% AJ + 70% PJ

15.3 16.80

0.29

3.50

AJ = “Agbalumo” Juice

PJ = Papaya Juice

Table 4: Physical Composition of Juice Blends _________________________________________ Parameters Sample

Viscosity

Colour

100% AJ

12.20

2.00

100% PJ

14.20

2.00

70% AJ + 30% PJ

13.00

1.90

60% AJ + 40% PJ

13.10

1.90

50% AJ + 50% PJ

13.30

2.00

40% AJ + 60% PJ

13.40

1.90

30% AJ + 70% PJ

13.60

2.00

AJ = “Agbalumo” Juice

PJ = Papaya Juice

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May. 2014. Vol. 2, No.1

ISSN 2311 -2476

International Journal of Research In Agriculture and Food Sciences © 2013 - 2014 IJRAFS & K.A.J. All rights reserved http://www.ijsk.org/ijrafs.html

2.1 Sensory analysis. The mean scores of the Hedonic Scale Test (table 1) in which the extent of the differences measured by multiple comparison analysis are summarized. The higher the measure score indicate, the lesser the rating of the sample for that particular quality attribute. Pure juice from Chrysophyllum albidium (“Agbalumo”) scored the highest in figure but the lowest quality. These observations show that for all the parameters tested for sensory attributes, pure “Agbalumo” juice was the least desired.

fruits were collected at mature stage. This might be the reason for good palatability and acceptability of some of the blends. Ascorbic is one of the major nutrients (source of vitamin C) that is obtained mainly from fruits. Apart from the sweet sensation, aroma, flavour of ripe fruits, the nutritional point of view should also be of importance to consumers. The results in table 3 showed that the values of the blends ranged from 9.36mg/100g to 16.80mg/100g respectively while AJ and PJ had 12mg/100g and 10.60mg/100g respectively. Taylor reported 47.6mg/100g for African Star Apple pulp, 48mg/100g for papaya (1987), while Keshiro in 1985 reported 38.2 + 3.8mg/100g for papaya. At the end of four weeks of storage, the values recorded for the various blend were relatively stable. The negligible decrease in ascorbic acid content of the various blends could be attributed to oxidation, which occurs in fruit juices during the storage period and is highly dependent on the presence of oxygen in the head space or dissolved in the juice (Costa et al; 2003). The results of the study show that an appreciable amount of juice could be made from African Star Apple and Papaya.

40% AJ blended with 60% PJ and 30% AJ with 70% PJ received the best quality as rated by the panelists while pure AJ was rated the poorest. 60%AJ blended with 40% PJ, 50% AJ with 50% PJ, 40% AJ with 60% PJ and 30% AJ with 70% PJ were rated better for flavour and were generally accepted by panelists when compared to other samples that were rated. There were no significant differences for taste for all the samples at 5% level of significant. The sharp acid taste and flavour observed for the AJ may have contributed to its low acceptability score. Table 2 shows the scores of the ranking test. The results depict that juice blends of 40% AJ with 60% PJ and that of 30% AJ with 70% PJ were most preferred while pure AJ and that of 70% AJ blended with 30% PJ were the least preferred. 40% AJ blended with 60% PJ and that of 30% AJ blended with 70% PJ were significantly different from other samples and were on the highest side. Pure AJ and that of 70% AJ blended with 30% PJ were also significantly different in that they were the least preferred. 60% AJ blended with 40% PJ and that of 50% AJ blended with 50% PJ show no significant difference.

Table 4 shows the physical properties of the juice blends. It was noticed that pure Chrysophyllum albidium juice and that of papaya are relatively stable as depicted by the colour index values read in the spectrophotometer while in the blended samples, slight changes in their colour index values were noticed, which could be attributed to the interactions between the chemical properties of each fruit or Maillard reactions and oxidation of ascorbic acid (Ahly, 1993). Viscosity values of the various samples are shown in table 4. It was observed that the sample which was pure papaya juice had the highest value while the least figure was noticed with African Star Apple juice. It was observed that the result was in line with the submission that viscosity of samples increase each time they were determined due to the fact that they tended toward the state of a puree as their particles tended to settled as they were stored and thus from a restriction to flow.

2.2 Chemical analysis of the juice blends. Table 3 showed some of the chemical properties of the blend of juices made from African Star Apple and Papaya fruits. The chemical properties of the juice blends were monitored over four (4) weeks. The juice blends had their pH values stable over the period. The overall results indicated that there were negligible changes in all the parameters measured. The total titratable acidity of the samples with larger portion of AJ was higher than those with larger portion of PJ.

CONCLUSION

Total Soluble Solids (TSS) of the fruit juices indicates maturity of the fruits sourced for the research. TSS of the various blends was in the range of 15.20 -18.00% while AJ and PJ had 23% and 11.5% respectively. The stability of the Brix over the short period of storage indicates that the

Juice production from a blend of “Agbalumo” and papaya could give a satisfactory and acceptable product comparable with any commercial juice products. The low Vitamin C content observed with the samples could be boosted. Fortification with Vitamin C for large

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May. 2014. Vol. 2, No.1

ISSN 2311 -2476

International Journal of Research In Agriculture and Food Sciences © 2013 - 2014 IJRAFS & K.A.J. All rights reserved http://www.ijsk.org/ijrafs.html

scale production would be ideal to forestall the situation of inadequate quantity of ascorbic acid. Based on the sensory evaluation by 28 panelists mostly untrained, samples with blends of 40% AJ and 60% PJ, 30% AJ with 70% PJ. 50% AJ with 50% PJ and 60% AJ blended with 40% PJ were accepted. There were some significant differences among the samples for all the quality attributes measured except for taste. For all the samples analysed, samples with lesser quantities of AJ

were most preferred while those with larger quantities of AJ were least accepted. Further studies should be conducted on the utilization of indigenous fruits in this respect in order to forestall wastages and to improve the income generation of the rural farmers. Above all, preservation of these juices is important because of the seasonality of its production which makes it abundantly available during its season and scarce during off season. Presentation of National Home Economics Workshop at Ahmadu Bello University, Zaria, Nigeria.

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