Effect of milling and preparation method on the physical properties and quality of moin-moin (steamed paste)

Moin-moin is steamed cowpea paste native to Nigeria. This product is classified as a protein/starch gel with the dominate portion of the gel network consisting of cowpea starch. Moin-moin was prepared from starting materials (cowpea meal and cowpea flour) and compared to moin-moin prepared from dry, whole, undecorticated cowpea seeds. Texture profile measurements showed that moin-moin made from cowpea flour (small particle size) formed a firmer structure when compared to moin-moin made from either cowpea meal or whole, dry cowpea seeds. Starting materials with smaller particle sizes and longer cooking times produced stickier moin-moin. The cowpea solids to water ratio was shown to affect the firmness of moin-moin, where a 3.75:1 ratio of solids to water produced a firmer product than other concentrations. Generally, color was unaffected across treatment regimens as identified by an expert sensory panel, although instrumental color measurements showed significant differences for hue angle and chroma. This study demonstrated that the particle size of this food ingredient contributes significantly to its functionality in food formulations.