A proof-of-concept for the fabrication of a self-polymerizing system for sampling of gut microbiome in the upper gastrointestinal (GI) tract is presented. An orally ingestible microdevice is loaded with the self-polymerizing reaction mixture to entrap gut microbiota and biomarkers. This polymerization reaction is activated in the aqueous environment, like fluids in the intestinal lumen, and causes site-specific microsampling in the gastrointestinal tract. The sampled microbiota and protein biomarkers can be isolated and analyzed via high-throughput multiomic analyses. The study utilizes a hollow microdevice (Su-8, c.a. 250 µm), loaded with an on-board reaction mixture (iron chloride, ascorbic acid and poly(ethylene glycol) diacrylate monomers) for diacrylate polymerization in the gut of an animal model. An enteric-coated rat capsule was used to orally gavage these microdevices in a rat model, thereby, protecting the microdevice in the stomach (pH 2), but releasing them in the intestine (pH 6.6). Upon capsule disintegration, microdevices were released in the presence of luminal fluids (in the small intestine region), where iron chloride reacts with ascorbic acid, to initiate poly(ethylene glycol) diacrylate polymerization via a free radical mechanism. Upon retrieval of microdevices, gut microbiota was found to be entrapped in the polymerized hydrogel matrix, and genomic content was analyzed via 16s rRNA amplicon sequencing. Herein, the results show that the bacterial composition recovered from the microdevice closely resemble the bacterial composition of the gut microenvironment to which the microdevice is exposed. Further, histological assessment showed no signs of local tissue inflammation or toxicity. This study lays a strong foundation for the development of untethered, non-invasive microsampling technologies in the gut, and advances our understanding of host-gut microbiome interactions, leading to better understanding of their commensal behavior and associated GI disease progression in the near future.
This study investigated the effectiveness of visible-near-infrared (VISNIR) spectroscopy at classifying Australian lamb for: a) ultimate pH (pH 24), b) meat tenderness (i.e. shear force at day 5 of ageing, SF5) and c) intramuscular fat (IMF) content at 24 h post-slaughter using a custom-made handheld probe coupled with the ASD Labspec Pro instrument. VISNIR predictive regression models were developed. In the loin muscle (M. longissimus thoracis et lumborum), the models classified the predicted pH 24, SF5 and IMF content at above or below a threshold value with 94%, 98% and 88% accuracy, respectively. The observed difference between the actual and predicted value (i.e. the standard error of cross validation, SECV) for ultimate pH and IMF content are approaching accuracies required to attain highly reliable Meat Standards Australia grading standards. However, further development is required to improve the SECV for SF5.
Plant proteins are receiving growing interest from the food and beverage industry. However, the properties of these proteins are still insufficiently characterised. The present study investigated the associative phase separation between potato protein (PP) isolate and anionic polysaccharides (PS), namely alginate (ALG), carboxymethylcellulose (CMC), and gum arabic (GA) to further the understanding of interactions between PP and commonly used PS with potential applications in the food industry. Through biopolymer titration and acid-ification, the effect of PP-PS mixing ratio (0.1-5:1, at 0.1 wt%) and pH (9-3) was investigated. The complexation process was characterised on micro- and macroscale by turbidimetry, electrophoretic light scattering, isothermal calorimetry, and precipitate composition was analysed. Turbidity measurements showed that ALG, CMC, and GA were saturated with PP at ratios of 5:1, 3:1, and 2:1, respectively. Isothermal calorimetry measurements confirmed that there was no additional binding at higher mixing ratios. Turbidimetry also indicated that PP and PS formed soluble complexes above pI, at highly alkaline pH. ALG, possessing the highest electrostatic charge density, yielded the most pronounced enthalpy change upon addition of PP, indicating more heat was released by the electrostatic complexation compared to GA and CMC. This could explain the resultant highest PP binding capacity and a precipitate that did not dissociate at low pH. At certain mixing ratios, PP and GA formed micro-dispersions, while complexing with ALG or CMC predominantly resulted in soluble complexes or insoluble precipitate. During acidification, the charges of the complexes followed the trend of PS instead of PP, suggesting the PP was internalised in the complexes.
