Título da Dissertação: Utilização de Resíduo de cervejaria (TRUB) no enriquecimento proteico de gelado comestível.

Orientadora: Profa. Dra. Paula Toshimi Matumoto Pintro, 

Data da Defesa: 22/02/2019



INTRODUCTION. Beer production has increased in the few last years, especially by China, the United States and Brazil. From 1998 to 2017 this increase was 0.65 billion hectoliters of beer, which resulted in a high generation of waste. The wastes obtained, brewer’s spent grain, residual yeast and hot trub, are moist, voluminous, and have high nutritional value. Brewer’s spent grain and residual yeast are generally used for animal feed and fertilizer production, while trub is limited in use due to the presence of bitter compounds. These compounds come from hops, especially tannins, water-soluble phenolic compounds. Trub has high moisture, high protein and carbohydrates, and its composition may change depending on the type of beer and the ingredients used in its production. To enable the use of its nutrients in human food, bitterness reduction technologies need to be employed, reducing waste, adding value to the waste, and reducing environmental impacts. One of the foods that can be enriched with new ingredients, in order to improve the flavor, aroma, texture, nutritional and functional properties, is ice cream. The ice cream could be obtained by common freezing of a stable emulsion, or by liquid nitrogen which may be formed of fat, protein, non-fatty milk solids, sugars, stabilizers and emulsifiers. However, the addition new ingredients to the ice cream may change its technological properties, which need to be evaluated. AIMS. This work aimed to enable the use of trub in human food through the process of extraction of its bitter compounds, to evaluate its nutritional and technological properties before and after the process; and also analyze the influence of the addition of the waste as source of protein in the properties of the ice cream. MATERIAL AND METHODS. In order to reduce the bitterness of trub, 5 sequential aqueous extractions were performed at high temperature (100 °C/1 h each extraction). Two fractions were obtained; a liquid fraction (containing bitter compounds) and a solid fraction (the trub after the extraction process; TAP). Both the fractions and the trub before the extraction process (TBP) were evaluated for the physicochemical composition, structure and technological properties. TAP was used for protein enrichment of ice cream frozen by liquid nitrogen and three formulations were prepared, ice cream standard (ICS), ice cream with whey protein (ICW) and ice cream with trub (ICT). Analyzes of chemical composition, rheological properties, texture, overrun, melt rate and scanning electron microscopy were performed. RESULTS AND DISCUSSION. The extraction process was able to change the chemical composition of the waste. The bitterness of TBP was significantly reduced in the TAP, while the protein content increased from 26.51% to 70.26%. TAP presented a branched network and a structural change, caused by protein denaturation and solubilization of compounds, mostly carbohydrates and phenolic compounds, which had their concentration reduced in TAP. The essential amino acid content of TAP was comparable to that of other protein sources. The solubility index and water absorption index were significantly reduced in TAP while the oil absorption capacity was not altered. The antioxidant activity of TAP was reduced due to the lower content of phenolic compounds in the waste after the process.
FTIR analysis was able to prove the changes in the chemical composition of waste during the extraction steps, which resulted in a waste even more nutritious, due to the high protein content. TAP was used for protein enrichment of ice cream and was able to alter its technological properties. The enrichment altered the viscosity of the formulations, obtaining a higher viscosity of the ICT formulation, as well as higher consistency index, hysteresis area and hardness. The ICT also obtained a lower melting and overrun rate compared to the other formulations. The ICW and ICT formulations had more than 5% protein, obtaining protein source products. CONCLUSIONS. The use of TAP has improved the technological properties of ice cream and has shown that it can be used as a food ingredient. The reduction of bitterness and the high protein content allow its use in the food industry. Key words: Byproducts, protein concentrate, bitterness, phenolic compounds

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