Control of mixing step in the bread production with weak wheat flour and sourdough

Recently, several old Italian grain varieties have been reinstated, and the market seems to reward the breads made with these flours. Among such varieties, cultivar Verna appears to be interesting because the regular consumption of bread obtained by this variety and sourdough provides beneficial effects on human health such as the improving of the lipid, inflammatory, and hemorheological profiles. However, flours derived from Verna shows low technological performances. For example, the W value of these flours, obtained with alveoghraphic tests and considered as the commercial standard for the flour “strength” evaluation, is largely inferior than the W values of the commercial flour blends currently used in the bread making process. Moreover, the W values broadly change among the batches of Verna flours, whereas, usually, commercial blends are provided to bakeries with standard technological properties. Hence, these properties of Verna flour could lead to developed or overworked doughs and therefore to breads of worse quality. In addition, the previous mentioned large variability of flours from Verna can affect also the sourdough microbiota. For these reasons the composition and activity of the sourdough microorganisms should be controlled while the mixing process should be able to adapt to the different flour properties. Some works, in literature, report that monitoring the electrical consumption could provide useful information about the dough rheology, and this could be used to monitor the mixing step. In the present work the effect of different mixing times are evaluated on breads made with Verna flour type 2 leavened with sourdough. Tests were carried out at industrial scale in two different days. During the tests the electric consumption was monitored to highlight some features suitable for the mixing phase control. The breads were evaluated in terms of loaf volume measurement, crumb image analysis and losses of moisture content during storage. The results show that the composition of the sourdough microbiota and the mixing time affects the produced bread, especially when it is baked with low technological performance flours. Bread baked with an appropriate mixing time shows higher loaf volumes and lower water losses during storage

Quantifying the Effects of Ethanol and Temperature on the Fitness Advantage of Predominant Saccharomyces cerevisiae Strains Occurring in Spontaneous Wine Fermentations

Different Saccharomyces cerevisiae strains are simultaneously or in succession involved in spontaneous wine fermentations. In general, few strains occur at percentages higher than 50% of the total yeast isolates (predominant strains), while a variable number of other strains are present at percentages much lower (secondary strains). Since S. cerevisiae strains participating in alcoholic fermentations may differently affect the chemical and sensory qualities of resulting wines, it is of great importance to assess whether the predominant strains possess a “dominant character.” Therefore, the aim of this study was to investigate whether the predominance of some S. cerevisiae strains results from a better adaptation capability (fitness advantage) to the main stress factors of oenological interest: ethanol and temperature. Predominant and secondary S. cerevisiae strains from different wineries were used to evaluate the individual effect of increasing ethanol concentrations (0-3-5 and 7% v/v) as well as the combined effects of different ethanol concentrations (0-3-5 and 7% v/v) at different temperature (25–30 and 35°C) on yeast growth. For all the assays, the lag phase period, the maximum specific growth rate (μmax) and the maximum cell densities were estimated. In addition, the fitness advantage between the predominant and secondary strains was calculated. The findings pointed out that all the predominant strains showed significantly higher μmax and/or lower lag phase values at all tested conditions. Hence, S. cerevisiae strains that occur at higher percentages in spontaneous alcoholic fermentations are more competitive, possibly because of their higher capability to fit the progressively changing environmental conditions in terms of ethanol concentrations and temperature

Microrganismi e composti bioattivi nel vino

Il comparto vitivinicolo italiano rappresenta un’eccellenza riconosciuta a livello mondiale, e si è affermato nel tempo soprattutto per il netto miglioramento della qualità nella produzione. Molta parte di questo successo è dovuta alle nuove conoscenze acquisite in ambito microbiologico, poi trasferite nei processi di produzione e trasformazione della materia prima, per giungere al prodotto finito: dal campo alla cantina, si può dire. L’obiettivo del libro è proprio documentare la complessità dell’attività microbiologica che può influire, positivamente o negativamente, su tutte le fasi della produzione a partire dalla vigna, passando per la cantina e terminando in bottiglia al momento del consumo. Gli autori affrontano prima di tutto l’ecosistema microbiologico del sistema vitivinicolo, per poi passare alle questioni centrali: i lieviti di interesse enologico e gli aspetti biotecnologici (selezione e produzione di starter, fermentazioni guidate e miste). Indagano inoltre il ruolo dei batteri nelle fermentazioni secondarie (malolattica e acetica) e dedicano una sezione alla gestione della qualità nei processi fermentativi (alterazioni microbiche, metodi di controllo, igiene in cantina). Infine, illustrano le principali metodiche per l’analisi microbiologica. Microbiologia della vite e del vino è un testo aggiornato e completo, che guida alla comprensione di un tema complesso, quello delle fermentazioni in ambito enologico, fornendo non solo il necessario sostegno teorico, ma anche soluzioni utili per condurre in pratica un processo fermentativo secondo obiettivi stabiliti