Aloísio José Antunes

Rearing the larvae of the blowfly Chrysomya chloropyga (Wiedemann) (Diptera, Calliphoridae) on oligidic diets

The growth of Chrysomya chloropyga (Wiedemann) larvae was compared on three different oligidic diets and mice carcass. The following performances in terms of gain in body weight were obtained: mice carcass (61.5 mg), whole dried milk plus whole dried egg (56.5 mg), whole dried milk plus casein (56 mg) and whole dried milk (55 mg). The period of most rapid growth was also different for each dietary media. This is the first time C. chloropyga has been reared on oligidic diets.

Albumen foam stability and s-ovalbumin contents in eggs coated with whey protein concentrate

Food products such as breads, cakes, crackers, meringues, ice creams and several bakery items depend on air incorporation to maintain their texture and structure during or after processing. Proteins are utilized in the food industry since they improve texture attributes through their ability to encapsulate and retain air. The objectives of this work were to quantify s-ovalbumin contents in albumen and to determine alterations in egg white foam stability in fresh eggs, and in eggs coated and non-coated with a whey protein-based concentrate film (WPC), stored at 25°C for 28 days. The volume of drained liquid was higher in non-coated eggs than in coated eggs stored at 25°C at all storage periods. The difference on the third day of storage was in the order of 59% between coated and non-coated eggs, while on the twenty-eighth day it was 202%. During the storage period, an increase in pH and drainage volume was observed for non-coated eggs. After three days, the non-coated eggs showed a s-ovalbumin content 33% higher than coated eggs; this increase jumped to 205% at 28 days of storage. There was a positive correlation between s-ovalbumin content and the volume of drained liquid for coated and non-coated eggs; in other words, when the s-ovalbumin content increased, there was an increase in the volume of drained liquid and a decrease in foam stability. WPC coating maintain egg quality, since it is an effective barrier against the loss of CO2, avoiding changes in the pH of egg white.

Perfil de textura e capacidade de retenção de água de géis ácidos de concentrado protéico de soro de leite

A capacidade dos concentrados proteicos de soro de leite (CPS) de formar geis e importante propriedade funcional. O objetivo deste estudo foi avaliar a influencia das variaveis concentracao de proteina, pH, temperatura e tempo de desnaturacao, nos intervalos de 8 a 12%; 4,0 a 5,2; 81 a 89oC e 15 a 27 minutos, respectivamente, no perfil de textura e capacidade de retencao de agua de geis acidos de CPS. O perfil de textura foi determinado em texturometro TAXT2 e a capacidade de retencao de agua avaliada atraves da umidade espremivel dos geis. O delineamento estatistico foi um planejamento fatorial 24 completo. Os geis de CPS apresentaram os maiores valores de firmeza, coesividade, elasticidade e capacidade de retencao de agua, de maneira geral, nas maiores faixas de concentracao proteica, tempo e temperatura de desnaturacao. Com relacao a variavel pH, geis formados em pH 4,0 apresentaram-se mais elasticos e com maior capacidade de retencao de agua, enquanto que os geis formados em pH 4,9 a 5,2 mostraram-se mais firmes e coesos.

Aplicação de filmes proteicos à base de soro de leite

The efficiency of whey protein films packaging was evaluated. The packaging system consisted of whey protein films closing the top extremity of synthetic plastic container. Slices of apple were packed and stored at room temperature (25 °C) and at 10 °C. Modified atmosphere packaging (N2 gas flushing) was studied to verify the oxygen permeability of the films. Whey protein films (6.5% of protein, 3.0% of glycerol, and pH 7.0) were obtained by thermal denaturation, emulsification (0.5% (w/w) with stearic acid), and enzymatic modification (10U/g protein of transglutaminase, ACTIVA-TG). Mechanical properties (tensile strength and elongation at break), water vapor permeability, and coloropacity properties of different films were evaluated. The film integrity was observed during the packaging and storage processing associated to the good mechanical properties. The water vapor permeability was evaluated by weight loss, moisture content, and texture profile of apple slices. The results showed that the whey protein films presented a moderated moisture barrier if compared with systems with no covering. The browning of the apple slices was investigated associated to the polyphenoloxidase action in presence of oxygen.

Perfil de textura e umidade espremível de géis do albume de ovos recobertos com soro de leite

A gelatinizacao e uma importante propriedade funcional das proteinas alimentares, devido ao seu grande potencial de uso nos alimentos estruturados. As proteinas da clara do ovo de galinha tem sido extensivamente usadas como ingredientes em alimentos processados. O objetivo deste trabalho foi avaliar as mudancas no pH, no perfil de textura e na umidade espremivel de geis de clara de ovos de galinha com e sem cobertura de concentrado proteico de soro de leite, armazenados a 25oC, por 3, 7, 10, 14, 21 e 28 dias. A dureza do gel do albume de ovos sem cobertura foi maior do que a de ovos recobertos, durante todos os periodos de armazenamento. Nao houve efeito do tempo de armazenamento na dureza dos geis dos ovos sem cobertura. Em ovos cobertos, a regressao linear explicou 60% do comportamento da dureza em relacao ao periodo de armazenamento. No caso da elasticidade, nao houve interacao entre periodo de armazenamento e a cobertura. Houve diferenca entre as medias dentro de cada periodo, mas nao durante o armazenamento. A maior elasticidade foi dos geis de ovos sem cobertura, comparados com os geis de ovos recobertos. O indice de coesividade e a mastigabilidade de geis de ovos sem cobertura foi maior que o de geis de ovos recobertos, em todos os periodos de armazenamento. A percentagem de umidade espremivel (UE) de geis de clara de ovos recobertos foi maior do que a de ovos sem cobertura em todo o periodo de estocagem.

Mechanical and permeability properties of milk protein films

Edible films present a potential alternative for replacing plastic films used for packaging in food industry. One of the major advantages is the environmental appeal of this technology, which produces no packaging waste. Some films made with other edible materials have found commercial applications, and many more are being developed using a myriad of food based components. This paper focuses on some important characteristics of films produced with sodium and calcium caseinates. The effects of caseinate type and concentration, plasticizer concentration and pH were studied. Major parameters investigated were solubility, tensile properties, water vapour and oxygen permeabilities. Caseinate films showed high solubility at pH range 6.0-8.0 and complete insolubility at pH 3.0 and 4.0. Calcium caseinate films had a higher tensile strength and a lower % elongation at break than sodium caseinate films. There was not significant difference in water vapour and oxygen permeabilities between sodium and calcium caseinate films.

Influência da adição de íons Ca++ e Mg++ na dureza de géis de concentrado proteíco de soro de leite bovino

Inumeros estudos vem sendo realizados com o objetivo de compreender o comportamento das proteinas do Concentrado Proteico de Soro (CPS). A capacidade destas proteinas em formar geis estaveis a temperaturas entre 70oC e 90oC, e uma propriedade funcional importante para a confeccao de varios produtos alimenticios, tais como: produtos de padaria, carneos, texturizados e lacteos. A concentracao proteica, pH, composicao ionica e temperatura podem ser controladas para obter um gel com as caracteristicas desejadas. Neste trabalho foi investigado o efeito dos ions metalicos bivalentes Ca++ e Mg++, na propriedade de dureza de geis de CPS induzidos termicamente. Dispersoes proteicas a 6; 7 e 8% de proteina do CPS a pH 6,3 com 0; 7,5; 15; 30 e 75mm de CaCl2 ou MgCl2 foram aquecidas a 75oC por 45 min, resfriadas a 4oC por 12 horas, e os geis avaliados em um texturometro TA-XT2. Os geis formados com maiores concentracoes do sal adicionado obtiveram maiores valores de dureza na faixa estudada. Nas concentracoes de 15 a 75mM os valores de dureza dos geis com a adicao de CaCl2 foram significativamente maiores (p<0,05) do que com adicao de MgCl2. Na concentracao de 8% de proteinas do CPS ambos os tratamentos atingem o maior valor de dureza (p<0,05) a 30mM do sal adicionado. O calcio ionico mostrou ter um importante papel na formacao do gel de proteinas do soro.