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Estudo da resistência de pectinas a processos térmicos de transformação em preparados de fruta
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A pectina é amplamente utilizada na indústria alimentar para conferir estabilidade e consistência às formulações. Contudo, parâmetros de processamento como a temperatura e o tempo podem comprometer essas propriedades. Assim, este trabalho centrou-se na avaliação da resistência de cinco tipos de pectina ao binómio tempo–temperatura, de forma a compreender até que ponto as suas características são afetadas por diferentes condições térmicas. As gamas de temperatura testadas foram de 85-87 ºC, 90–93 °C e 94–97 °C, por um período máximo de 2 horas. As pectinas estudadas foram de baixo teor de metoxilação, nas formas não amidadas, parcialmente amidadas e amidadas, incluindo adição de cloreto de cálcio. Verificou-se que, em todas as pectinas sem adição de cálcio, o aumento da temperatura e/ou do tempo de exposição reduziu a capacidade de gelificação, evidenciado pelos maiores valores na escala de Bostwick, indicativos de menor firmeza da matriz. Em quatro das cinco pectinas, atingiu-se o valor máximo da escala, passando a consistência a ser descrita em segundos. À medida que a temperatura aumentou, esse ponto foi atingido cada vez mais cedo. A presença de cálcio conferiu maior coesão às amostras, embora insuficiente para evitar a desestruturação ao longo do tempo, reforçando o impacto do binómio tempo–temperatura. A pectina não amidada (pectina 3) revelou maior sensibilidade térmica, enquanto a pectina 4 se destacou por ser a mais estável. As pectinas 1 e 5 (parcialmente amidadas) apresentaram comportamentos semelhantes, e a pectina 2, embora amidada, mostrou ainda alguma sensibilidade ao calor. Um estudo com formulações completas incluindo outros ingredientes, realizado a 98 °C, serviu para simular condições industriais, no qual se observou uma maior estabilidade face às formulações base. Contudo, exceto a pectina 4, todas ultrapassaram os limites aceitáveis. O uso de amido modificado reduziu a perda de consistência, mas não foi o único fator, já que outros ingredientes mostraram contribuir para uma maior estabilização. Em suma, ficou claro que o controlo rigoroso da temperatura e do tempo de processo é essencial para preservar as propriedades reológicas da pectina.
Pectin is widely used in the food industry to provide stability and consistency to formulations. However, processing parameters such as temperature and time can compromise these properties. Thus, this work focused on the evaluation of the resistance of five types of pectin to the time–temperature binomial, to understand to what extent their characteristics are affected by different thermal conditions. The tested temperature ranges were 85–87 °C, 90–93 °C, and 94–97 °C, for a maximum period of 2 hours. The pectins studied were low-methoxyl pectins, in non-amidated, partially amidated, and amidated forms, including the addition of calcium chloride. It was found that, in all pectins without calcium addition, the increase in temperature and/or exposure time reduced the gelling capacity, evidenced by the higher values in the Bostwick scale, indicative of lower matrix firmness. In four out of the five pectins, the maximum value of the scale was reached, with consistency then being described in seconds. As the temperature increased, this point was reached increasingly earlier. The presence of calcium provided greater cohesion to the samples, although insufficient to prevent breakdown over time, reinforcing the impact of the time–temperature binomial. The non-amidated pectin (pectin 3) showed greater thermal sensitivity, while pectin 4 stood out as the most stable. Pectins 1 and 5 (partially amidated) showed similar behaviors, and pectin 2, although amidated, still showed some sensitivity to heat. A study with complete formulations including other ingredients, carried out at 98 °C, served to simulate industrial conditions, in which greater stability was observed compared to the base formulations. However, except for pectin 4, all exceeded acceptable limits. The use of modified starch reduced the loss of consistency, but it was not the only factor, since other ingredients also contributed to greater stabilization. In summary, it became clear that strict control of processing temperature and time is essential to preserve the rheological properties of pectin.
Pectin is widely used in the food industry to provide stability and consistency to formulations. However, processing parameters such as temperature and time can compromise these properties. Thus, this work focused on the evaluation of the resistance of five types of pectin to the time–temperature binomial, to understand to what extent their characteristics are affected by different thermal conditions. The tested temperature ranges were 85–87 °C, 90–93 °C, and 94–97 °C, for a maximum period of 2 hours. The pectins studied were low-methoxyl pectins, in non-amidated, partially amidated, and amidated forms, including the addition of calcium chloride. It was found that, in all pectins without calcium addition, the increase in temperature and/or exposure time reduced the gelling capacity, evidenced by the higher values in the Bostwick scale, indicative of lower matrix firmness. In four out of the five pectins, the maximum value of the scale was reached, with consistency then being described in seconds. As the temperature increased, this point was reached increasingly earlier. The presence of calcium provided greater cohesion to the samples, although insufficient to prevent breakdown over time, reinforcing the impact of the time–temperature binomial. The non-amidated pectin (pectin 3) showed greater thermal sensitivity, while pectin 4 stood out as the most stable. Pectins 1 and 5 (partially amidated) showed similar behaviors, and pectin 2, although amidated, still showed some sensitivity to heat. A study with complete formulations including other ingredients, carried out at 98 °C, served to simulate industrial conditions, in which greater stability was observed compared to the base formulations. However, except for pectin 4, all exceeded acceptable limits. The use of modified starch reduced the loss of consistency, but it was not the only factor, since other ingredients also contributed to greater stabilization. In summary, it became clear that strict control of processing temperature and time is essential to preserve the rheological properties of pectin.
Descrição
Palavras-chave
Pectina Binómio tempo-temperatura Cálcio (Ca²⁺) Consistência Método de Bostwick Pectin Time–temperature binomial Calcium (Ca²⁺) Consistency Bostwick method
Contexto Educativo
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Licença CC
Sem licença CC