<p>The Food Processing and Postharvest Handling
Innovation Lab (FPIL) project seeks to reduce food loss and link up consumers
with food-to-food fortified instant products that are enriched with
micronutrient sources that target vitamin A, zinc, and iron deficiencies. These
are mostly maize-based products, but may be combined with other cereals, such
as sorghum, and pseudocereals, such as amaranth. The general goal of this
thesis study was to facilitate the adoption of extrusion technology to process
instant flours, assess the acceptance and willingness to pay (WTP) for these
products, and to assess the health impacts of the products on gut health. A
low-cost, single-screw extruder was used that was developed at Purdue, and has
been placed in different locations in Africa country study sites. The first study
aimed to optimize process conditions of a low-cost single-screw extruder,
currently done at 35% feed moisture, for African small- to medium-scale
entrepreneurs to produce good quality and low-cost pregelatinized instant pearl
millet porridge flours and other whole grains by relating feed moisture (27,
29, 31, 33, and 35%) to extrusion energy, drying time and physicochemical
properties. We found that we could lower the feed moisture to 27% and still
attain good pasting profiles of the porridges, reduce drying time, have better
expansion of the extrudates, obtain increased <i>L</i>* color values of the
flours, and with a higher extrusion energy but lower drying time. In
conclusion, the single screw extruder can be efficiently operated at 27% feed
moisture compared to the currently used 35% feed moisture and obtain instant
flours with desired quality. It is not known whether higher extrudate energy
consumption may be offset by the lower drying time representing lower drying
energy. In
the second study, we investigated extrusion enhance <i>in vitro</i> fecal
fermentation of maize bran, which has been characterized by a poor gut
microbiota fermentation property due to its highly crosslinked and densely
branched arabinoxylan chemical structure, making it poorly available to the gut
microbiota. We hypothesized that this dense cell wall matrix can be opened for
better fermentation by applying extrusion. Test conditions of a twin-screw
extruder at Purdue were low (200 RPM) and high (400 RPM) shear rates applied to
a maize meal and bran mixture (60:40) at different feed moisture conditions
(20, 25, 30%). <i>In vitro</i> fermentation
of test materials was conducted on stool samples from three donors. Extrusion
increased total short chain fatty acids and produced individualized donor effects
on the gut microbiota. Some extruder test condition effects were observed on
certain bacteria. For example, extrusion at 30% feed moisture and 400 RPM tended
to increase genera of <i>Subdoligranulum</i> and <i>Eubacterium hallii</i> and <i>Ruminococcus</i>
<i>torques</i> groups in Donor 1 compared to non-extruded bran. There was also
a trend of increase in <i>Subdoligranulum</i> and <i>Blautia</i> in extruded
compared to non-extruded bran in Donor 2. In Donor 3, <i>Lachnospiraceae
NK4A136</i> group was increased at 20 and 25% feed moistures at 200 RPM and 30%
feed moisture at 400 RPM compared to non-extruded bran. In the
final study, we investigated the acceptance and WTP for instant fortified
flours using the Becker-DeGroot-Marschak mechanism when consumers are incrementally
given nutrition information and demonstration how to reconstitute instant
flours. This study was conducted in Eldoret, Kenya. Participants preferred the
fortified thick porridge higher in maize content than fortified thin porridge
prepared from the same blend. Contrarily, thin porridge made from fortified
flour with higher sorghum content was ranked more highly than for the
corresponding thick porridge. Participants were willing to pay more for instant
fortified products higher in sorghum when given product name and nutrient
composition, even without a practical demonstration of how to reconstitute the flours.
For the instant product higher in maize, consumers needed demonstration of how
to reconstitute the instant flour for them pay a higher premium. These findings
suggest that food-to-food fortified instant porridge flours have the potential
to be adopted and can be used as a vehicle to deliver micronutrients to these
populations and that extrusion somewhat enhances fermentation of whole grain
fibers by the gut microbiome.</p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/14210885 |
| Date | 01 June 2021 |
| Creators | Emmanuel Ayua (10297847) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/STUDIES_ON_EXTRUSION_PROCESSING_OF_INSTANT_PORRIDGE_FLOURS_FOR_AFRICAN_PROCESSOR_OPTIMIZATION_ACCEPTANCE_MARKETABILITY_FOR_CONSUMERS_AND_IMPROVEMENT_IN_IN_VITRO_FECAL_FIBER_FERMENTATION/14210885 |
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