Texture and interlinked post-process microstructures determine the in vitro starch digestibility of Bambara groundnuts with distinct hard-to-cook levels

© 2019 Elsevier Ltd Particular storage conditions are described to promote the development of the hard-to-cook (HTC) phenomenon for most legumes. However, it is not clearly established whether the HTC phenomenon influences starch digestion kinetics. Therefore, this study explored how the HTC phenomenon influences in vitro starch digestion of Bambara groundnuts, taking into account three distinct HTC levels. Stored Bambara groundnuts required prolonged cooking times. Increasing storage time led to a decrease in the rate constant of texture degradation, signifying the development of the HTC phenomenon. For cooking times of 60 min and 120 min, high HTC level samples exhibited higher rate constants and extents of starch digestion compared to the fresh sample. The higher rate of digestion was attributed to the high hardness that resulted in greater cell rupture and faster access of amylase to starch. Adapting cooking times of Bambara groundnuts with distinct HTC levels to obtain equivalent hardness values and microstructures resulted in comparable starch digestion kinetics. Spectrophotometric analysis overestimated the amount of digested starch, in contrast to the more accurate HPLC analysis, which further provided more insight by quantifying multiple digestion products. This work demonstrates that it is the hardness and interlinked pattern of cell failure (microstructure) that determines starch digestion of Bambara groundnuts with distinct HTC levels.status: publishe

Molecular and rheological characterization of different cell wall fractions of Porphyridium cruentum

© 2018 Elsevier Ltd Cell wall related polysaccharides of the red microalga Porphyridium sp. were shown to be a promising source of new sustainable thickening agents. Isolated extracellular polysaccharides (EPS) consisted of high molecular weight polymers, showing a higher intrinsic viscosity compared to several commercially used hydrocolloids. Aqueous solutions of EPS (2% w/w) were characterized by substantial viscosities and weak gel behavior. Even though the extracted water soluble cell wall polysaccharides exhibited the same monosaccharide profile as EPS (composed of galactose, glucose, xylose and glucuronic acid), a lower molecular weight and intrinsic viscosity was observed for this fraction, resulting in poor rheological properties. Therefore, it was hypothesized that the physicochemical properties were related with a different molecular structural organization of these monosaccharides and sulfate groups. The main challenge for commercialization of extracellular polysaccharides of Porphyridium sp. remains the purification of these fractions to obtain polysaccharide extracts with low protein and salt contents.status: publishe

Prospective cohort study of the feasibility and yield of household child tuberculosis contact screening in Uganda

SETTING: Screening and isoniazid preventive therapy (IPT) of child contacts of tuberculosis (TB) patients is 'poorly implemented in resource-limited countries, in part due to difficulties in TB diagnosis in children. OBJECTIVE: To assess the feasibility and yield of hospital-based screening and IPT in Uganda, and to evaluate the utility of symptom-based screening. DESIGN: Household child (age <5 years) contacts of adults with pulmonary TB were assessed for TB or latent tuberculous infection (LTBI). Children classified as 'LTBI' or 'uninfected' were prescribed IPT and followed for 9 months. Screening algorithms based on combinations of symptoms associated with TB were constructed post hoc, and their performance evaluated against a radiological-based reference standard. RESULTS: Of 281 contacts (median age 33 months), 44 (15.7%) started anti-tuberculosis treatment and 234 (83.3%) received IPT, 80.3% of whom completed a 6 month course. After adjustment for age and human immunodeficiency virus status, cough (aOR 4.10, 95%CI 1.39-12.11) and reduced playfulness (aOR 7.79, 95%CI 2.12-25.18) were associated with radiological TB. Screening based on cough or reduced playfulness had a sensitivity of 81.8% and a negative predictive value of 97.6%. CONCLUSION: Hospital-based screening appears to be feasible, and confirms the potential utility of symptom based screening to select children for IPT and those for further investigations