Enzyme assisted juice extraction from Dacryodes macrophylla as a potential bio-resource for wine production

Atom fruit (Dacryodes macrophylla) is a Non-timber Forest Product (NTFP) that comprises a large seed, thick pulp, and a thin hard outer covering. The structural component of its cell wall and thick pulp make it difficult in extracting the juice. Also, Dacryodes macrophylla fruit is greatly underutilized, therefore the need to process and transform it into other value-added products. This work aims to enzymatically extract juice from Dacryodes macrophylla fruit with the aid of pectinase, ferment and test the acceptability of wine produced from this extract. The enzyme and non-enzyme treatments were carried out under the same conditions and their physicochemical properties such as pH, juice yield, total soluble solids, and Vitamin C were compared. A central composite design was used for the optimization of the processing factors for the enzyme extraction process. Enzyme treatment had a great impact on the juice yield (%) and Total soluble solids (TSS) (⁰Brix) of samples as it was as high as 81 ± 0.7% and 10.6 ± 0.02 ⁰Brix whereas, that of the non-enzyme treatments were 46 ± 0.7% and 9.5 ± 0.02 ⁰Brix respectively. However, the Vitamin C content of enzyme-treated juice decreased to 11.32 ± 0.13 mg/ml as compared to that of the non-enzyme-treated juice sample (15.7 ± 0.04 mg/ml). The optimum processing condition in the extraction of juice from the atom fruit was 1.84% enzyme concentration, 49.02 ֯C Incubation temperature, and 43.58 min Incubation time. During wine processing within 14 days of primary fermentation, the pH of the must decreased from 3.42 ± 0.07 to 3.26 ± 0.07 whereas the Titratable acidity (TA) increased from 0.16 ± 0.05 to 0.51 ± 0.0. The wine produced from Dacryodes macrophylla fruit showed promising results as its sensorial scores for all attributes including color, clarity, flavor, mouthfeel, alcoholic burn after taste and overall acceptability were all above 5. Thus, enzymes can be used to improve the juice yield of Dacryodes macrophylla fruit and hence, can be a potential bioresource for wine production.

Optimization of pectinase-assisted extraction of Annona muricata L. juice and the effect of liquefaction on its pectin structure

BACKGROUND

Soursop (Annona muricata L.) is an underutilized tropical and subtropical fruit with high nutritional and therapeutic benefits. This fruit is faced with enormous post-harvest losses due to its high perishability. This work was aimed to optimize the pectinase-assisted extraction conditions of soursop juice using Doehlert design and to study the effect of pectinase on its pectin structure.

RESULTS

The predicted models were validated for all the responses studied and the regression coefficients ranged from 0.905 to 0.987 (P ≤ 0.05). An incubation time of 172 min, enzyme concentration of 0.04% (w/w) and incubation temperature at 42.9 °C were found to be the optimal conditions for soursop juice extraction, which resulted in 75.20%, 3.74, 7.35 °Brix, 87.06%T, and 0.44% MAE for soursop juice yield (%), pH, total soluble solids (TSS) (°Brix), clarity (%T) and titratable acidity (% malic acid equivalent, MAE), respectively. Morphologically, untreated soursop pulp presented a non-uniform spherical surface; enzyme hydrolyzed soursop exhibited ruptured and wrinkled surface; meanwhile for the different pectin obtained, untreated soursop pectin depicted porous surface and enzyme hydrolyzed soursop pectin showed whirling rough surface. Fourier-transform infrared (FTIR) confirmed the presence of similar chemical group stretching and vibrations in commercial pectin and soursop pectin.

CONCLUSION

Under the optimum conditions, the numerical predictions were similar to the experimental data obtained, thus confirming the validity of the models. Application of enzyme treatment caused the breakdown of pectin structure as illustrated by scanning electron microscopy (SEM) and FTIR analyses.