Inoculation of Latilactobacillus sakei with Pichia kluyveri or Saccharomyces boulardii improves flavor compound profiles of salt-free fermented wheat-gluten: Effects from single strain inoculation.

Wheat-gluten, the protein-rich portion of wheat, can be processed to produce a highly savory sauce product after solid and liquid-state fermentation (SSF and LSF) with the inoculation of selected lactic acid bacteria (LAB) and yeast under salt-free condition. However, limited research has been done on the impact of different types of microbes in this process. This work studied the flavour impact on fermented wheat-gluten by the single inoculation of Latilactobacillus sakei or one yeast (Saccharomyces boulardii or Pichia kluyveri). Glucose was depleted during LSF in all treatments. Lactic acid production increased over time in L. sakei-fermented samples but not in yeast-fermented samples. Cysteine, serine and arginine remained low over LSF in L. sakei-fermented samples but increased in yeast-fermented samples. More fruity esters such as isoamyl acetate and isobutyl acetate were detected in samples fermented by P. kluyveri, while S. boulardii boosted the production of alcohols such as 3-methyl butanol and 2-phenylethyl alcohol. Principal component analysis revealed a clear difference in volatile profiles of the samples fermented with different strains. Therefore, the fermented sauce can potentially be processed into different flavor directions, and based on the flavor profile, be used in different food applications.

Proteomic profiling of barley spent grains guides enzymatic solubilization of the remaining proteins.

Within the brewing industry, malted barley is being increasingly replaced by raw barley supplemented with exogenous enzymes to lessen reliance on the time-consuming, high water and energy cost of malting. Regardless of the initial grain of choice, malted or raw, the resultant bulk spent grains are rich in proteins (up to 25% dry weight). Efficient enzymatic solubilization of these proteins requires knowledge of the protein composition within the spent grains. Therefore, a comprehensive proteomic profiling was performed on spent grains derived from (i) malted barley (spent grain A, SGA) and (ii) enzymatically treated raw barley (spent grain B, SGB); data are available via ProteomeXchange with identifier PXD008090. Results from complementary shotgun proteomics and 2D gel electrophoresis showed that the most abundant proteins in both spent grains were storage proteins (hordeins and embryo globulins); these were present at an average of two fold higher in spent grain B. Quantities of other major proteins were generally consistent in both spent grains A and B. Subsequent in silico protein sequence analysis of the predominant proteins facilitated knowledge-based protease selection to enhance spent grain solubilization. Among tested proteases, Alcalase 2.4 L digestion resulted in the highest remaining protein solubilization with 9.2 and 11.7% net dry weight loss in SGA and SGB respectively within 2 h. Thus, Alcalase alone can significantly reduce spent grain side stream, which makes it a possible solution to increase the value of this low-value side stream from the brewing and malt extract beverage manufacturing industry.

Whole grain in manufactured foods: Current use, challenges and the way forward.

Some countries now incorporate recommendations for increased consumption of whole grain (WG) into local dietary guidelines. Cereal and pseudo-cereal grains are good sources of complex carbohydrates, dietary fiber, proteins, phytochemicals, vitamins and minerals. However, research shows that the large majority of consumers are still falling short of WG consumption goals. To address this, we are actively involved in research to help increase the WG content of processed foods without compromising on taste and texture. In order to ensure consumer trust, the advancement of process technologies in incorporating WG to produce tasty food has to go hand in hand with well designed clinical trials that confirm the health benefits resulting from diets rich in WG.

In situ investigation of Geobacillus stearothermophilus spore germination and inactivation mechanisms under moderate high pressure.

Bacterial spores are a major concern for food safety due to their high resistance to conventional preservation hurdles. Innovative hurdles can trigger bacterial spore germination or inactivate them. In this work, Geobacillus stearothermophilus spore high pressure (HP) germination and inactivation mechanisms were investigated by in situ infrared spectroscopy (FT-IR) and fluorometry. G. stearothermophilus spores' inner membrane (IM) was stained with Laurdan fluorescent dye. Time-dependent FT-IR and fluorescence spectra were recorded in situ under pressure at different temperatures. The Laurdan spectrum is affected by the lipid packing and level of hydration, and provided information on the IM state through the Laurdan generalized polarization. Changes in the -CH2 and -CH3 asymmetric stretching bands, characteristic of lipids, and in the amide I' band region, characteristic of proteins' secondary structure elements, enabled evaluation of the impact of HP on endospores lipid and protein structures. These studies were complemented by ex situ analyses (plate counts and microscopy). The methods applied showed high potential to identify germination mechanisms, particularly associated to the IM. Germination up to 3 log10 was achieved at 200 MPa and 55 °C. A molecular-level understanding of these mechanisms is important for the development and validation of multi-hurdle approaches to achieve commercial sterility.