Comprehensive study on gluten composition and baking quality of winter wheat

Background and Objectives Protein and gluten content and composition are important for the baking quality of wheat flours. Our aim was to provide a comprehensive characterization of 82 wheat flours to analyze the influence of protein composition on rheological and baking quality parameters. Findings Protein composition, starch gelatinization behavior, as well as rheological (microfarinograph, gluten aggregation, extensibility), and baking parameters were determined. The correlation matrix showed no significant correlations between gluten composition and loaf volume. Parameters of the gluten aggregation test allowed a prediction of gluten, gliadin, and glutenin content with an absolute root mean square error of cross validation of 7.5, 6.0, and 3.2 mg/g, respectively, using partial least squares regression. Starch gelatinization temperature had an effect on gluten aggregation. Conclusions The gluten aggregation test was suitable to predict gluten, gliadin, and glutenin content. The lack of correlations between protein composition and loaf volume indicates that baking quality is the result of a complex combination of different parameters. Significance and Novelty Our study is the first to comprehensively analyze 82 wheat flours, especially in terms of gluten composition. We show that flour blends can reach excellent baking quality even if quality indicators like crude protein or extensibility are comparatively low

Influence of ISPs from a polar sea-ice microalga on whipped cream detected by cryo-Raman microscopy

The occurrence of recrystallization and large ice areas after storage of frozen food products makes the use of ice-structuring proteins (ISPs) in food products meaningful. Food products are frozen to extend shelf-life during long storage periods while preservation of the overall sensoric quality. Recrystallisation processes alter and, in the worst case, damage the structure of the food, resulting in an unsightly thawed e.g. cream cake or cream puff product. Freezing and freeze storage behaviour of various food products should be investigated in order to optimize the manufacturing of frozen products and to maintain the product quality with appropriate storage until the consumers usage. We present a study on the influence of ice-structuring proteins, isolated from the sea-ice microalgae Fragilariopsis cylindrus (fcISP), on frozen whipped cream. The individual phases of the frozen cream foam have been detected by cryo-Raman spectroscopy and visualized. The advantage of the unique cryo-Raman spectroscopy system available at the AWI is that the individual components can be detected not only qualitatively, but also localized in the frozen sample. We show that the fat and ice structure in frozen cream, and their temperature-induced changes, are well detectable by cryo-Raman spectroscopy. Furthermore, the effect of fcISPs on the microstructure shows an inhibition of ice recrystallization, leading to smaller grain aggregates and a finer fat distribution than without fcISPs. We therefore suggest that fcISPs are an effective mean in controlling recrystallization processes in frozen goods

Confocal Raman microscopy of frozen bread dough

The use of freezing technology is well established in industrial and craft bakeries and is still gaining importance. In order to optimize recipes and processes of frozen baked goods, it is essential to be able to investigate the products' microstructure. Especially ice crystals and their interaction with the other components of the frozen products are of interest. In this study, frozen wheat bread dough was investigated by confocal Raman microscopy. The Raman spectra measured within the dough were compared with spectra of the main components of frozen dough, i.e. ice, liquid water, starch, gluten and yeast. In this way, the spatial distribution of the single components within the dough was determined and corresponding images of the frozen dough microstructure were generated. On these images, ice appears as a continuous network rather than as isolated crystals. We suggest that this method may be appropriate for characterizing crystallization phenomena in frozen baked goods, allowing to better understand the reasons for quality losses and to develop strategies for avoiding such losses

Prediction of wheat gluten composition via near-infrared spectroscopy

Gluten composition is an important quality parameter for wheat flour, because it is strongly correlated to baking quality. Wheat proteins are commonly extracted stepwise and analysed using RP-HPLC-UV to determine the gluten composition. This procedure is very time-consuming and labour-intensive. Therefore, a new, fast and easy method to quantitate gluten proteins was established using NIR spectroscopy (NIRS). PLS-regression models were calculated containing 207 samples for calibration and 169 for test set validation. Albumin/globulin (ALGL), gluten, gliadin and glutenin content was predicted with a root mean square error of prediction (RMSEP) of 2.01 mg/g, 6.09 mg/g, 4.25 mg/g and 3.50 mg/g, respectively. High-molecular-weight glutenin subunits (HMW-GS) and low-molecular-weight glutenin subunits (LMW-GS) were predicted with a RMSEP of 1.12 mg/g and 2.38 mg/g. The relative error was too high for ALGL, LMW-GS and HMW-GS, but that of gluten, gliadins and glutenins was in a range comparable to the reference method. Therefore, the new NIRS method can be used to estimate the gluten composition of wheat flour, including the gliadin/glutenin and the LMW-GS/HMW-GS ratio

Microwave assisted freezing of meat and fish matrices

Several preservation methods have been investigated, developed and exploited over the last years but freezing still remains one of the most popular among them, which offers fresh-like characteristics on the food matrix after long period of storage. The freezing process of food matrices is affected by their dominant constituent which is water. The final quality of the frozen product depends on the phase transition or the crystallization process of changing water into ice. The size of the ice crystals is critical for the final quality of the frozen food. During the implementation of the FREEZEWAVE project, a novel more advanced experimental setup was designed and developed for the application of microwave radiation during freezing. The influence of microwave assisted freezing (MAF) on meat and fish matrices under different processing scenarios such as slow or fast MAF for fish and constant or pulsed MAF for meat was investigated. The microstructure of the frozen samples was evaluated with image analysis and positive results were acquired in both food matrices, showing a reduction of the size of ice crystals size. Sensory tests carried out by TTZ partner showing encouraging results. Further tests are needed to determine the kinetic parameters of quality change during storage under different temperatures

Evaluation of Microwave Assisted Freezing (MAF) impact on meat and fish matrices

International audienc

Sensory evaluation of potatoes, chicken meat, cod fish and emulsions after microwave-assisted freezing (FREEZEWAVE project)

International audienc

Microwave assisted freezing (MAF) of meat and fish matrices (FREEZEWAVE project)

International audienc