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Mestrado em Engenharia Alimentar - Instituto Superior de Agronomia Tempeh is an indonesian fermented food by the fungus Rhizopus oligosporus, which the production is beneficial as regards the improvement of the protein digestibility and nutritional value of legumes. The present work intended to optimize the production method of inoculum (R. oligosporus), while adding value to food industry (broken rice, wheat, corn and rye flours). The follow objective consisted in optimizing the production process of tempeh, using traditional Portuguese legumes (pea and lupine) in comparison with soy tempeh. Finally, texture parameters (firmness and cohesiveness) were evaluated by a TPA. Instrumental colour parameters, throughout the fermentation and after storage at refrigeration temperature were also evaluated. The results showed the viability of producing the inoculum using food industry by-products (5 days, 29 ° C), with rye, rice “carolino” and long grain rice flours yielding a higher sporulation. Soybean and pea tempeh complete fermentation after 48 h at 29 and 37 °C, respectively, while the lupine tempeh only after 72 h at 37 ° C. The highest values of firmness, cohesiveness and lightness (L *) were obtained at the end of fermentation. Significant variations in color, expressed in terms of a * and b * parameters, were observed

Mestrado em Engenharia Alimentar - Instituto Superior de Agronomia Fermented foods from Eastern countries, based on crop fermentations are among the most desired by consumers for their nutrition value and potential as Functional foods and for their diversity and originality. Yet, these products are usually produced by spontaneous and poorly characterized fermentations under non-controlled conditions, which are not compatible with the high quality standards demanded by Western consumers. Tempeh is a popular Indonesian fermented food, originally based on soybean fermented by Rhizopus oligosporus. The objective of this work was to produce safer and effective Rhizopus oligosporus inocula and design standard procedures for safe and consistent tempeh production and conservation. Additionally new tempeh-like fermented products were also produced. Rhizopus oligosporus growth and inoculum preparation and inoculum concentration added to the crop, were optimized to obtain standard tempeh with the desired organoleptic properties. Adjustments on the production steps described for the traditional tempeh manufacture (soaking and fermentation parameters) were also made. Using the optimized procedures, a standard method for inocula and tempeh production was developed. Tempeh maintained its organoleptic properties when stored under vacuum in thermo sealed polypropylene bags and frozen until consumption. The production of several varieties of tempeh using different crops was accomplished under these conditions.

Mestrado em Engenharia de Sistemas Bioenergéticos - Instituto Superior de Agronomia Bioethanol production from lignocellulosic materials is only viable if the process of converting the biomass to ethanol is efficient. One of the conditions that affect this efficiency is the resistance of the fermentative microorganisms to the toxic compounds that are formed during the necessary lignocellulosic materials pre-treatment. The current work analyzed the behavior of Saccharomyces cerevisiae growing on a medium containing inhibitory compounds to the fermentation, compounds that are present on an industrial lignocellulosic hydrolysate. The effect of the elimination of non-essential genes on the cells fermentative metabolism was studied. The non-essential genes eliminated were genes involved in the regulation and metabolism of nitrogen (TOR1, GLN3, PRO1, PUT4, ARO4), in the cell’s response to oxidative stress (SOD2, ZWF1, ADH6), osmotic stress (HOG1, TPS1, NTH1, HSP12) and general stress (HSP26), on the regulation of the intracellular pH (RIM101, VMA1), and in apoptosis (AIF1, FIS1). The results obtained from these procedures were indicative that some of these genes mutations are relevant for determining the fermentation efficiency. The behavior of four selected mutant strains was further characterized. Besides the determination of glucose concentration, extracellular pH and CFU at the beginning of stationary phase and glucose exhaustion, for these four chosen strains, the ethanol concentration and the influx and efflux of protons through the plasmatic membrane were also collected.