Guava Leaves Extract Used as Fruit Shelf Life Preservative -

Guava Leaves Extract Used as Fruit Shelf Life Preservative

Crude extract was obtained by crushing dry guava leaves into 100 g powder and adding 600 ml of boiled water. The mixture was allowed to stand for 1 hr to allow extraction. The extract was then filtered and used to determine its inhibition against fungi. The extract was also serially diluted to obtain 5 different concentrations which were used to determine their effectiveness in increasing the shelf life of the strawberries. The plates with the highest concentration of guava leaves extract had the lowest number of microbial colonies.

Inhibition of the Crude Extract against Fungi

Mueller Hinton agar was poured into a petri dish and allowed to solidify. A layer of fungi was spread on the agar. Holes were drilled into the agar and 0.1 ml of the crude extract was poured into the holes. A thin layer of the media was poured on top to prevent the extract from moving beyond the holes. The plates were incubated aerobically at 30°C and the hallo regions were observed and measured after 72 hr to determine the presence or absence of inhibition.

Effectiveness of the Crude Extract in Increasing the Shelf life of Strawberries

Serial dilution of 1 ml in 9 ml of distilled water was done up to 5 serial dilutions. Fresh strawberry fruits after two days they were dipped in guava leaves extract of different concentrations. 1 g of strawberry fruit from each concentration was serially diluted with sterile 0.85% NaCl. 4 decimal dilution of the sample were done. After homogenization, the last 3 dilution were plated on potato dextrose agar plates. The plates were incubated aerobically at 30°C. Microbial colonies were observed, counted and recorded after 48 hr of incubation. The procedure was repeated for 3 consecutive days.

Results for the Effectiveness of the Crude Extract in Increasing the Shelf life of Strawberries

Dilution of the sample was done to decrease the number of microbes to a limit that can be counted. Dilution 1 had the highest concentration of the extract while dilution 5 had the lowest concentration of the extract. The plates with the highest concentration of guava leaves extract had the lowest number of microbial colonies while the one with the lowest concentration on had the highest number of microbial colonies. Therefore, the extract was more effective in inhibiting fungal growth on strawberries when used at a higher concentration. This difference was because, under different concentrations, the phytochemical compounds present in the extract show different effectiveness in inhibiting fungi. The higher their concentration, the more effective they are in inhibiting fungi. These guava leaves extract that would help increase the shelf-life of strawberries.  

Recommendation

Further studies need to be conducted in order to:

1. Identify the components in the crude extracts causing inhibition against fungi.

2.. Identify the minimum inhibition concentration.

Reference:

Gituma, G.K. and Njue, L.G., 2019. Preservation of Strawberries Using Guava Leaves Extract. Asian Food Science Journal, 10(4), pp.1-7.