Enhanced accumulation of toxic compound in yeast cells having high glycolytic activity: a case study on the safety of genetically engineered yeast

The cellular level of methylglyoxal (MG), a highly toxic 2-oxoaldehyde, in Saccharomyces cerevisiae cells transformed with genes for some of the glycolytic enzymes was determined as an index of the safety of genetically engineered yeast and the level was compared with that in non-transformed control cells. the phosphoglucose isomerase (PGI), phosphofructokinase (PFK) and triosephosphate isomerase (TPI) activities significantly increased in the transformants and were approximately five-, three- and sevenfold higher, respectively, than those in the control. When these transformed cells were used for alcohol fermentation from glucose, they accumulated MG in cells at a level sufficient to induce mutagenicity. These results illustrate that careful thought should be given to the potential metabolic products and their safety when a genetically engineered yeast is applied to food-related fermentation processes.     

Determination of unprocessed genetically modified soybean in foods using simplex and duplex real-time PCR with an internal standard

We developed a method using an internal standard to determine the amount of unprocessed genetically modified organisms (GMO) in foods as GMO weight per weight of total food (w/w_tf) using real-time PCR. Food samples were spiked with an internal standard, a ColE1 plasmid, and DNA was extracted from the samples using a silica membrane-type kit and analysed using real-time PCR. The relationship between the GMO amount and the copy number ratio of the transgene to ColE1 in 0.1–5% w/w_tf GM soybean powders was found to have a correlation coefficient ( r ) of 0.97. GMO was quantified in food samples spiked with GM soybean (final amount 0.5% w/w_tf GMO). The average GMO amount ranged from 0.35% to 0.63% w/w_tf. The results show that our method should be useful for quantifying unprocessed GMO in foods. We also developed a duplex assay, which is simpler and more accurate than the simplex assay.     

Supplementation of pearl millet flour with soybean protein: effect of cooking on in vitro protein digestibility and essential amino acids composition

In vitro protein digestibility (IVPD) and amino acids profile of pearl millet (Dempy cultivar) supplemented with soybean protein (5–15%) were investigated. Supplementation of dempy flour with soybean protein steadily decreased IVPD with increasing the portion of soybean in the blend. The in vitro protein digestibilities of the cooked supplemented dempy flours were higher when compared with the raw ones, whereas the highest value was that of the 5% soybean protein. All essential amino acids of dempy flour were enriched on supplementation with soybean protein. The levels of amino acids increased with increasing the amount of soybean protein in the blend. Essential amino acids in dempy supplemented with 15% soybean are comparable to those in the FAO reference pattern. Supplementation increased significantly lysine to 1.5–2.4 folds. Essential amino acids content remained higher in the cooked composite flours when compared with the cooked native dempy flour.     

Interaction of mulberry anthocyanins with soybean protein isolate: effect on the stability of anthocyanins and protein in vitro digestion characteristics

The interactions of anthocyanins and proteins might mutually influence each other on the physicochemical and functional properties. In this study, the interaction mechanism of soybean protein isolate (SPI) with mulberry anthocyanins (MA), and its effect on the thermal stability of anthocyanins and protein subunits’ digestibility were investigated through multiple spectroscopies and in vitro gastrointestinal models. Results showed that cyanidin-3-O-glucoside (C3G), the main anthocyanin monomer in MA, could bind to SPI through hydrophobic interactions, resulting in static fluorescence quenching of SPI. The secondary structure of SPI changed by binding to C3G, with an increase of β-sheet and a decrease of α-helix and random coil. The formation of the SPI-MA complexes improved the thermal stability of MA at 353 K, while, no significant protection occurred during heating at 368 K. Complexation with MA promoted the digestibility of SPI by pepsin, especially the α′ and α subunits of β-conglycinin and the basic subunit of glycinin, and slightly delayed the digestibility of SPI under intestinal fluid. These results provide an in-depth understanding of the influence of the protein-anthocyanin interactions on the stability of anthocyanins and protein digestibility.     

Potato: a comparative study of the effect of cultivars and cultivation conditions and genetic modification on the physico-chemical properties of potato tubers in conjunction with multivariate analysis towards authenticity

Potato (Solanum tuberosum L.) is a highly nutritious, mild flavored, easy to blend food that has many possibilities for "building in" desired nutrients. Varietal and environmental differences are known to exist in the shape, size, and nutritional content of potatoes. Different populations opt for varying sensory properties in relation to their diets. Potatoes are a low energy food in comparison to cereals and legumes. The aim of this review was to present an update of the currently conducted studies both on the characterization of several potato varieties (physical, chemical, and sensory analysis) and by means of genetic modification. Towards this target, five comprehensive tables were compiled where all recent data (physicochemical properties) and GM varieties were presented in conjunction with multivariate analysis (chemometrics). The latter was shown to be effectively used towards authenticity purposes (identification of geographical origin, variety, GM).