Back ground

Processing orange fresh sweet potato (OFSP) into puree that can be subsequently incorporated in various food products such as bakery, baby foods offers convenience and add value to the crop. To expand use of OFSP puree in sub-Saharan Africa, a non-expensive storage method that preserve β-Carotene and offer an acceptable shelf-life is required, moreover, products made from the stored OFSP puree should not be markedly different than those from fresh puree. The use of vacuum packaging potential offer puree processors ability to transport and store OFSP puree without need of refrigeration. We investigated retention of β-Carotene content in vacuum packed OFSP puree treated with preservatives and stored at ambient (temperature 15-23°C) for up to 12 weeks.

Methods

OFSP puree from two varieties (vita and Kabode) was separately treated with preservatives (sodium benzoate and potassium sorbate) at 0.1%w/w and two commercial natural antimicrobial agents (Maysa antifungal and antibacterial) at 0.08%w/w, then packed in polythene bags with or without vacuum seal. High performance liquid chromatography (HPLC) was used to analyze β-carotene content in puree sampled at 0, 4, 8 and 12 weeks. All analysis was carried in triplicate, and results subjected to statistical analysis using Genstat edition 13.

Results

Significant difference (P≥ 0.05) was observed between β-carotene content of vita and kabode varieties during all time points. At 12 weeks, puree treated with different preservatives and with different packing condition showed significant difference on β-Carotene content. Highest β-Carotene retention after 12 weeks in vacuum packed puree was observed in Potassium Sorbate and Sodium Benzoate (0.1%w/w) (81% and 96% in Vita and Kabode respectively). Retention was 80% and 82% in vita and kabode respectively in vacuum packed puree treated with Maysa antifungal and antibacterial.

Conclusion

Β-carotene content of the OFSP puree does not change significantly during the first 3 months at room conditions (temperature range 15-23°C). Using potassium sorbate (0.1%) and sodium benzoate (0.1%) in combination with vacuum packing can increase the shelf storability of puree without significant loss of β-carotene. This has potential breakthrough for expanding use of OFSP puree in Sub-Saharan Africa.