Title: Effects of infestation of Rhyzopertha dominica F. on sorghum endosperm: A laser scanning confocal microscopy and differential scanning calorimetery study Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: September 21, 2008
Publication Date: September 21, 2008
Citation: Park, S., Wilson, J.D., Arthur, F.H., Bean, S., Schober, T.J., Tilley, M. 2008. Effects of Infestation of Rhyzopertha dominica F. on Sorghum Endosperm: A Laser Scanning Confocal Microscopy and Differential Scanning Calorimetery Study. [abstract]. Cereal Foods World. 53:A72. Technical Abstract: Infestations of Rhyzopertha dominica (F.), the lesser grain borer, can cause loss of biomass and decrease grain quality through feeding damage or contamination with insect fragments and uric acid. R. dominica can change dough properties of wheat and negatively affect bread quality. However, few published studies have described the effects of feeding damage by R. dominica on sorghum. A previous study showed that R. dominica readily attacked sorghum kernels, and the resulting feeding damage affected the kafirin content and flour pasting properties. In this study, we investigated the physical structure of infested sorghum endosperm using laser scanning confocal microscopy (LSCM) and analyzed thermal properties using differential scanning calorimetery (DSC). The LSCM of roughly ground sorghum flour revealed that infested sorghum endosperm had a weakened or a loose protein matrix with unattached protein bodies and starch granules, compared to undamaged sorghum flour which contained a tight protein matrix covering protein bodies and starch granules. DSC thermograms showed significantly lower onset temperatures (71.0-71.5 degrees Celsius) for infested endosperm compared with uninfested endosperm (73.2 degrees Celsius). Peak temperatures decreased gradually from 77.5 degrees Celsius (undamaged endosperm) to 74.9 degrees Celsius as the damage increased with an increasing number (10, 20, 40, and 80) of adult R. dominica introduced in each of the sample jars containing ca. 175g of sorghum. Gelatinization endotherm area and delta H were lower for undamaged endosperm (19.8 mJ and 4.5 J/g, respectively) when compared with the endosperm from the samples most heavily infested with R. dominica (35.4 mJ and 8.0 J/g, respectively). These results may be due to increased starch granule exposure in the infested endosperm.