Using synchrotron FTIR spectroscopy to determine secondary structure changes and distribution in thermoplastic protein

Brewing by-product valorisation: trub debittered for nutritional and quality improvement of pasta

Trub, a brewing by-product, can be used as alternative ingredient for foods nutritional enrichment after its bitter compounds extraction. Study presents the optimisation of bitter compounds extraction from trub by Box-Behnken design, and use of debittered trub (DT) as new ingredient to enrich pasta. Bitterness extraction process was evaluated at different pH levels, time and extraction steps, and physical-chemical properties of DT (obtained under optimal conditions) were evaluated. Pasta was enriched with DT (5%, 10% and 15%) and its physical-chemical and quality properties were evaluated. Protein structure and chemical composition of trub were altered after process, also modifying its technological properties. Pasta with 10% DT increased in 33.51% protein content. Interaction of DT and wheat proteins resulted in a more compact structure, and DT water absorption capacity provided pasta texture changes. DT use improved pasta nutritional and quality properties, enabling trub valorisation and its use as vegetable proteins alternative source.

Effect of Different Cooking Methods on Proton Dynamics and Physicochemical Attributes in Spanish Mackerel Assessed by Low-Field NMR

The states of protons within food items are highly related to their physical attributes. In this study, the effect of cooking methods including boiling, steaming, roasting and frying on proton dynamics, physicochemical parameters and microstructure of Spanish mackerel was assessed by low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) techniques. The treatment of cooking resulted in a significant reduction of proton mobility and declined freedom of protons. The state changes of protons can be monitored easily in an intuitive and non-destructive manner during various cooking process. The treatments of boiling, steaming, roasting and frying resulted in different cooking loss and similar water-holding capability. A significant increase of total carbonyl content and thiobarbituric acid reactive substances was found, while a decrease of the values for free thiols and surface hydrophobicity was observed. The analysis of circular dichroism spectroscopy and cryo-scanning electron microscopy showed significant structural change. The correlation coefficients of R_cal² and R_cv² from partial least squares (PLS) regression models were more than 0.980, suggesting good correlation between LF-NMR data and hardness, resilience, springiness, chewiness, gumminess, and adhesiveness. Good recoveries and a relatively small coefficient of variation (CV) were obtained from the PLS regression models, indicating good reliability and accuracy in predicting texture parameters for mackerel samples.

The Role of Extrusion Conditions on the Mechanical Properties of Thermoplastic Protein

Mechanical properties of Novatein thermoplastic protein compounded at different extrusion temperatures and processing water contents have been examined in a factorial experiment. Thermoplastic proteins are moisture sensitive and can be prone to thermal degradation during processing. Processing water was varied between 30 and 45 parts per hundred parts bloodmeal while the extrusion temperature was varied between 120 and 150 °C to identify a processing window suitable for process scale up. To resolve any effects processing water had on protein-protein interactions from its plasticising effect, injection molded specimens were mechanically tested both as molded and after conditioning at controlled temperature and humidity. Despite all conditioned samples having approximately the same moisture content, mechanical properties were different. Tensile strength and modulus decreased with increasing processing water at the same equilibrium moisture content. DMA and WAXS suggested this was due to changes in chain mobility within the amorphous phase of the material, rather than conformational change towards a more ordered state. Properties of unconditioned specimens were mostly dependent on the plasticising effect of different amounts of processing water remaining in the material after injection molding. Extrusion temperature had very little effect on mechanical properties, suggesting that Novatein is robust enough to handle some temperature variations during processes such as injection molding.

Molecular interactions of milk protein with phenolic components in oat-based liquid formulations following UHT treatment and prolonged storage

BACKGROUND

Nowadays there is a growing demand for nutritionally balanced breakfast beverages enriched with functional ingredients including wholegrain oat, which is rich in phenolic acids. Such beverages typically contain added food ingredients (e.g. milk protein, sugar and lipids) and undergo thermal processing that initiates many molecular processes. Therefore, this work aims to investigate the molecular interactions between milk protein and phenolic acids that govern bioactivity in model oat-based beverages.

RESULTS

Findings showed the susceptibility of ferulic and p-coumaric acids, in model oat beverages, to ultra-high temperature (UHT) processing at 145 °C for 8 s. Among model beverages, those with added milk protein demonstrated a considerable loss of phenolic acids following UHT processing due to the interaction between these micronutrients and the protein. The nature of molecular interactions was mainly categorized as covalent with hydrogen bonds playing a supportive role.

CONCLUSION

UHT processing of oat-based beverage formulations facilitates the formation of protein-phenolic acid complexes, which are largely covalent and static in nature. This finding underlines the ability of UHT treatment to induce chemical modifications of food ingredients. © 2017 Society of Chemical Industry.

A review of recent trends in polymer characterization using non-destructive vibrational spectroscopic modalities and chemical imaging

This review focuses on the recent developments in vibrational spectroscopy and chemical imaging (i.e. Raman, Near Infrared, Mid Infrared) to characterize polymers in diverse forms, their behaviour and transient phenomenon. First, important polymeric properties and traditional methods of their characterization are outlined. Then relative advantages & disadvantages have been presented of different characterization methods are presented. This is followed by a detailed review of applications of chemical imaging and spectroscopic techniques in polymer characterization, including the limitations encountered. The article ends with a discussion on the future of chemical imaging with regards to polymer characterization.

Changes to amino acid composition of bloodmeal after chemical oxidation

The effect of oxidative decolouring with peracetic acid on the physical and chemical characteristics of bloodmeal proteins was investigated by assessing protein solubility, molecular weight distribution and final amino acid composition.

Effect of oxidative treatment on the secondary structure of decoloured bloodmeal

Synchrotron-based Fourier-transform infrared (FTIR) spectroscopy was used to assess the effect of peracetic acid decolouring on the spatial distribution of secondary structures within particles of bloodmeal.