Food Processing

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Browsing Food Processing by Author "Calvin Onyango"

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    Composition of Polyphenols in Wheat Bread Supplemented with Pleurotus ostreatus Mushroom
    (2015) Stella W. Ndung’u; Christina A. Otieno,; Calvin Onyango; Fredrick Musieba
    Pleurotus ostreatus mushrooms were blanched, milled into flour and incorporated into wheat flour at 5, 10 and 15%. These composite flours, together with composite breads developed from these formulations were evaluated for polyphenols, namely flavones and isoflavones. Wheat flour and wheat bread were used as control samples. Extraction of polyphenols was done using ethanol as a solvent and analyzed using gas chromatographmass spectrometry. It was not possible to make bread with 15% mushrooms. Quantities of different flavones and isoflavones evaluated increased significantly (p<0.05) with increasing supplementation of mushroom flour in wheat flour. Composite breads were also observed to have higher contents of flavones and iso flavones as compared to bread prepared from wheat flour only. Composite flour with 15% mushrooms had highest quantities of flavones and isoflavones while composite bread with 10% mushroom flour had significantly higher (p<0.05) levels of these compounds. Caffeic acid was the most abundant amongst all the flavones analyzed in wheat mushroom blends while genistein was the most abundant isoflavone. Flavones and isoflavones in human nutrition protect against oxidative stress and also provide medicinal properties such as antimicrobial, antiviral and anticancer benefits. Pleurotus mushrooms are a good source of these important compounds hence incorporating them in daily diet like bread would ensure constant supplementation for improved health and nutrition.
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    Debranched Cassava Starch Crystallinity Determination by Raman Spectroscopy: Correlation of Features in Raman Spectra with X-Ray Diffraction And 13C CP/MAS NMR Spectroscopy
    (Carbohydrate Polymers, 2012-01-04) Christopher Mutungi; Lars Passauer; Calvin Onyango; Doris Jaros; Harald Rohm
    Because starch crystallinity influences the physical, mechanical, and technological aspects of numerous starch-based products during production and storage, rapid techniques for its assessment are vital. Samples of different levels of crystallinity were obtained by debranching gelatinized cassava starch, followed by subjection to various hydrothermal treatments. The recrystallized products were further subjected to partial hydrolysis with a mixture of α-amylase and glucoamylase prior to freeze–drying. Crystallinities were determined using X-ray diffraction (XRD) and 13C CP/MAS NMR spectroscopy, and correlated with FT-Raman spectra features. XRD crystallinities ranged between 0 and 58%, and agreed with crystalline-phase fractions (R2 = 0.99) derived from the respective 13C CP/MAS NMR spectra. A strong linear correlation was found between crystallinities and integrated areas of the skeletal mode Raman band at 480 cm−1 (R2 = 0.99). With appropriate calibration, FT-Raman spectroscopy is a promising tool for rapid determination of starch crystallinity.
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    Modification Of Gluten-Free Sorghum Batter and Bread Using Maize, Potato, Cassava or Rice Starch
    (LWT - Food Science and Technology, 2011-04) Calvin Onyango; Christopher Mutungi; Günter Unbehend; Meinolf G. Lindhauer
    Gluten-free sorghum bread was made from cassava, maize, potato or rice starch and sorghum in the ratios 10:90, 20:80, 30:70, 40:60 and 50:50. The other baking ingredients, on flour-weight-basis, were water (100%), sugar (6.7%), egg white powder (6%), fat (2%), salt (1.7%) and yeast (1.5%). Increasing starch content changed the batters’ consistencies from soft doughs to thin pourable batters. Increasing starch content decreased crumb firmness and chewiness, and increased cohesiveness, springiness and resilience of all breads. Cassava-sorghum and rice-sorghum breads had better crumb properties than maize-sorghum or potato-sorghum breads. Although the crumb properties of all breads declined (i.e. firmness and chewiness increased; cohesiveness, resilience and springiness decreased) on storage, the formulation containing 50% cassava starch retained the best overall texture.
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    Nutrient composition, sensory attributes and starch digestibility of cassava porridge modified with hydrothermally-treated finger millet
    (Science Direct, 2020) Calvin Onyango; Susan Karenya Luvitaa; Guenter Unbehend; Norbert Haase
    ABSTRACT Cassava (CAS) porridge has low energy density and is a poor source of several nutrients. Its energy density and nutrient composition is normally improved by blending it with other flours. The aim of this study was to determine the effect of hydrothermally-treated (HTT) finger millet on nutrient composition, sensory attributes and starch digestibility of cassava porridge. Composite flour had higher protein, fibre, lipid and mineral content than cassava flour. The high α-amylase activity of HTT finger millet permitted the quantity of CAS-HTT flour to be raised from 9.5% w/v to 19% w/v without altering the free-flowing drinkable consistency of porridge. Partial substitution of CAS with HTT finger millet had no effect on starch digestibility and tannin content but increased the phytate content of CAS-HTT porridge. Hydrothermally-treated finger millet masked the aroma and colour of cassava resulting in dark-coloured CAS-HTT porridge with a bitter taste.
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    Starch and Modified Starch in Bread Making: A Review
    (African Journal of Food Science, 2016-09-27) Calvin Onyango
    Starch is an important source of energy in human nutrition. It is also widely used as a processing aid in several food and non-food industries. Starch in wheat flour contributes to the development of optimal bread crumb and crust texture. It is also responsible for physical deterioration of bread quality through staling. Starch is mainly extracted from starch-rich plants such as cereals, root and tuber crops and legume seeds. It can be modified using chemical, physical or enzymatic techniques to obtain modified starch. Traditional plant breeding or genetic modification can also be used to produce starches with modified functionalities. Modified starches are essential food processing aids because of their enhanced functional properties. The aim of this paper is to review the role of starch in bread making and subsequently elucidate the influence of modified starch on the quality of wheat bread.