The effect of natural and artificial preservatives and storage temperature on the pH and microbial load of freshly produced apple (&lt;i&gt;Malus domestica&lt;/i&gt;) juice

J.O Ekanem,O.O Ekanem

doi:10.4314/as.v18i1.3

Abstract

Apple (Malus domestica) juice was treated with 0.5 g/ml garlic, 0.5 g/ml ginger, 0.25 g/ml mix of ginger and garlic and 0.05% (w/v) of sodium benzoate respectively where the ginger, garlic and sodium benzoate serves as natural and artificial preservatives. Their effects on the apple fruit juice were evaluated during 8 days of storage at 4 o C and at room temperature (28±2 o C). The microbial counts ranged from 4.0×10 4 to 7.0×10 3 cfu/ml and from 1.0×10 4 to 2.0×10 3 cfu/ml for bacteria and fungi, respectively in the samples treated with ginger, garlic and sodium benzoate and from 1.2×10 4 to 2.2×10 4 cfu/ml in the apple juice without treatment. Juice treated with sodium benzoate had the least microbial contamination while the untreated juice had the highest. There was marginal decrease in pH values across treatments in stored apple juice with juice stored at 4 o C showing the least change in pH compared to that stored at room temperature. The results obtained show that the preservatives exhibited antimicrobial effect on the microbial load and that pH has a significant impact on the shelf-life of the fruit juice as the microbial load was least when stored at low temperature the pH as acidity tends to be inclined towards low pH. Key words: apple juice, pH, microbial load, sodium benzoate, temperature

Highlights

The apple tree (Malus domestica) is a deciduous tree in the rose family best known for its sweet, pomaceous fruit, the apple(GRIN, 2012) and stands1.8 to 4.6 m (6 to 15 ft) tall in cultivation and up to 39 ft (12 m) in the wild (GRIN, 2012)
The addition of the preservatives helps to reduce the bacterial load in all juice sample treatments stored at 4oC and room temperature (28±2oC) with juice and sodium benzoate showing the highest reduction from 4.0 × 104 to 8.0 × 103cfu ml-1 and 4.0 × 104 to 7.0 × 103cfu ml-1 for juice stored at 4oC and room temperature respectively
There was no increase in the bacterial load for control samples stored at 4oC but increase in the sample stored at room temperature 4.2 × 104 to 4.0 × 104cfu ml-1 and 4.1 × 104 to 6.0 × 104cfu ml-1

Summary

Introduction

The apple tree (Malus domestica) is a deciduous tree in the rose family best known for its sweet, pomaceous fruit, the apple(GRIN, 2012) and stands1.8 to 4.6 m (6 to 15 ft) tall in cultivation and up to 39 ft (12 m) in the wild (GRIN, 2012). Commercial growers aim to produce an apple that is 7.0 to 8.3 cm (2.75 to 3.25 in) in diameter, due to market preference Some consumers, especially those in Japan, prefer a larger apple, while apples below 5.7 cm (2.25 in) are generally used for making juice and have little fresh market value. When closely evaluating the composition of apple juice and other apple products, it becomes apparent that the lack of fat, cholesterol and sodium are just a few of the many reasons these products are an important part of a healthful dietary routine Fruit sugars such as those found in apple products serve as an immediate source of energy and because apple products taste so good, they are readily consumed by infants and children. Apple juice serves as an excellent means of providing essential fluids to the body and is unlikely to cause allergic reactions

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Conclusion