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. 2022 Apr 6;11(7):1051.
doi: 10.3390/foods11071051.

Effect of Orange-Fleshed Sweet Potato Purée and Wheat Flour Blends on β-Carotene, Selected Physicochemical and Microbiological Properties of Bread

Derick Malavi  1   2   3 , Daniel Mbogo  1   4 , Mukani Moyo  1 , Lucy Mwaura  1 , Jan Low  1 , Tawanda Muzhingi  1   5
Affiliations

Effect of Orange-Fleshed Sweet Potato Purée and Wheat Flour Blends on β-Carotene, Selected Physicochemical and Microbiological Properties of Bread

Derick Malavi et al. Foods. .

Abstract

Partial substitution of wheat flour with orange-fleshed sweet potato (OFSP) purée in bread can increase vitamin A intake among consumers. The study investigated the influence of wheat flour substitution with 20-50% of OFSP purée on proximate composition, color, β-carotene, water activity, and microbial keeping quality. The moisture content, crude protein, crude fat, total ash, crude fiber, and carbohydrate in bread ranged from 28.6-32.7%, 9.9-10.6%, 5.0-5.5%, 1.9-3.2%, 1.4-1.8%, and 79.1-80.9%, respectively. β-carotene, total ash, and crude fiber contents in bread, and Hunter color values a*, b*, chroma, and ∆E significantly increased with the addition of OFSP purée. Total viable counts (TVC), yeast, and molds in bread ranged from 2.82-3.64 log10 cfu/g and 1.48-2.16 log10 cfu/g, respectively, on the last day of storage. Water activity, TVC, and fungal counts were low in sweet potato composite bread as compared to white bread. Total β-carotene in OFSP bread ranged from 1.9-5.4 mg/100 g (on dry weight). One hundred grams of bread portion enriched with 40% and 50% OFSP purée provides more than 50% of vitamin A dietary requirements to children aged 4-8 years. Incorporation of up to 50% OFSP purée in wheat flour produces a relatively shelf-stable, nutritious, and health-promoting functional bread.

Keywords: biofortification; composite bread; orange-fleshed sweet potato; purée; vitamin A deficiency; β-carotene.

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Conflict of interest statement

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

Figures

Figure 1
Figure 1
HPLC chromatogram showing beta-carotene peaks in the extract of orange-fleshed sweet potato composite bread at 450 nm. Peak identification: (a) 13-cis β-carotene, (b) all-trans ß-carotene (c) 9-cis β-carotene.
Figure 2
Figure 2
Water activity profile in bread during storage. The bars indicate standard errors of means. White bread (♦); 20% OFSP bread (■); 30% OFSP bread (▲); 40% OFSP bread (∗); 50% OFSP bread (∗).
Figure 3
Figure 3
Changes in: (a) total viable counts (TVC); (b) yeast and molds in bread during storage. The bars indicate standard errors of means. White bread (♦); 20% OFSP bread (■); 30% OFSP bread (▲); 40% OFSP bread (∗); 50% OFSP bread (∗).
Figure 4
Figure 4
(a) Score plots, and (b) correlation loading plots from the principal component analysis of wheat−OFSP purée bread quality attributes.
See this image and copyright information in PMC

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