BRUNA MERIGIO ALCANTARA

Título da Dissertação: AVALIAÇÃO DA QUALIDADE E DO PROCESSO DE CERVEJA SEM ÁLCOOL TIPO STOUT OBTIDA PELO PROCESSO DE OSMOSE REVERSA.

Orientador: Prof. Dr. Antonio Roberto Giriboni Monteiro

Data da Defesa: 27/03/2015

RESUMO GERAL

INTRODUCTION. The market of low-alcohol and non-alcoholic beer has been increasing due to factors such as health concerns, high-calorie content, strict traffic laws, religion and pregnant women. Beer presents compounds of great nutritional interest such as B-complex vitamins, antioxidants, minerals, fibers, proteins and carbohydrates leading studies to recommend it as good food source. The definition of non-alcoholic beer varies around the world; in Arabic countries, the maximum allowed alcohol concentration is 0.1% (v/v); in Italy, 1.2%, (v/v) Europe and Brazil, 0.5% (v/v). The greatest challenge for the brewing industry is to develop low-alcohol or non-alcoholic beer with organoleptic characteristics similar to regular beer. There are many processes used for the beer’s production with reduced content or Non-alcoholic, biological (fermentation) and physical (thermal and with membranes) But those with the best results currently, processes involving membranes produce the best beers. The method of reverse osmosis involves the beer passing through a semi-permeable membrane under high-pressure conditions. This type of membrane is permeable to water, alcohol, and other small molecules; larger molecules responsible for organoleptic characteristics remain in the concentrate beer. In the first stage of the reverse osmosis, it occurs the concentration of the original beer by removing the alcohol and water not adding the concentrate with demineralized water; at the second stage, the removed value is replaced with demineralized water – a process called difiltration, which occurs until the desired volume of alcohol is reached. The membranes used in the process are usually of asymmetric structures, with active layer of cellulose, polyamide, polyimide, polyester or polyester-sulfone - placed in modules with different geometric forms (plan, tubular or spiral).
OBJECTIVES. Develop a non-alcoholic Stout black beer using reverse osmosis and assess its process and physical, chemical parameters.
MATERIALS AND METHODS. Beer type Foreign Extra Stout was purchased at Cathedral Beer Supply, located in Maringá, state of Paraná, Brazil, following the norms by the Beer Judge Certification Program (BJCP). The beer samples were initially decarbonized through magnetic agitation with a maximum temperature maintained until 20ºC. Four samples were generated with varied parameters of dilution and temperature: C1 and C3 – 1L demineralized water plus 1L of beer, and C2 and C4 – 2L of beer with process temperatures C1 and C3 20ºC, C2 and C4 30ºC. The process was carried out on a module of reverse osmosis with a spiral polyestersulfon membrane with an area of 0.3 m2. The temperature was controlled using a refrigeration bath with pressure of 4.9 bar for all of the samples. For samples C1 and C3, the process was concentration until 1.5L and subsequent difiltrations until the total removal of alcohol; reaching this point, above 0.5L were removed from the concentrate for the initial beer volume to return. For samples C2 and C4, we repeated the process applied to samples C1 and C3 until the stage of total alcohol removal, eliminating only the last stage reaching a final volume of 1.5L, completed with demineralized water until 2L.
The analyses involved the fouling coefficient; permeate flow, color, bitterness, pH, alcohol content, antioxidant activity DPPH and phenolic compounds. The obtained results were assessed using analysis of variance (ANOVA) and the averages submitted to Tukey test at 5% probability.
RESULTS AND DISCUSSION. Regarding the fouling, all of the samples presented significant results for permeate flow, having increased with time and temperature; however, the temperature should not be too increased in order to prevent beer degradation. By analyzing the results of bitterness, we observed no significant differences; lower temperatures in diluted samples lead to lower bitterness loss. Regarding the color, all of the samples are within the standards by BJCP 2014. The pH varied from 4.2 to 4.4, within the interval between 3.8 and 4.7, which prevents microbial growth. The analysis of alcohol content indicated that at the temperature of 20º in diluted samples, the process of total alcohol removal is longer than for temperatures around 30ºC in concentrated samples. The results of total phenolic compounds presented variation, while the values of antioxidant activity using method DPPH are lower than the analyzed studies.
CONCLUSIONS. Results of is study showed the possibility of producing black alcohol-free beer quality. However, to ensure color, bitterness, pH and antioxidants beer, the best option temperature was 20ºC and the diluted samples. Still it is necessary more studies to optimize the process.
Keywords: Non-alcoholic black beers, Membrane, Alcohol content.

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