Extraction of pectin from apple pomace

As apple-processing units are now in expansion in Brazil, industrial by-products like pomace play an important role in pectin manufacture. The objective of this article was to determine a pratical follow-up to the extraction of pectin from apple pomace and to characterize it in a laboratory, on a small scale, aiming at establishing the optimum conditions for acid extraction. The highest yields were obtained when [1]apple pomace was dried and ground to obtain an apple flour to be used as raw material, [2] citric or nitric acids were used and [3] when the citric acid concentration was 6.2 g/100 ml and the time of reaction was 153 minutes. The apple variety in itself was not significant in pectin yield. The degree of esterification (DE = 68.84 %) of the product obtained, as well as its physical looks, show the success of pectin extraction

Influência da concentração de ácidos no processo de extração e na qualidade de pectina de bagaço de maçã

In concentrated apple juice processing units the pomace is washed with tap water in order to increase the yield so that the industrial by-product contains no more soluble pectin but only insoluble protopectin. In this article the main objectives were to establish a procedure to prepare the apple pomace as raw material and to extract pectin with several kinds and concentration of mineral and organic acids considering its degree of esterification, determined by titrimetric and spectroscopic techniques, as quality references. Dried apple pomace, with 12% moisture, showed 33.4% reducing sugars and 40% dietary fiber in dry weigth basis, with proper color. The extraction processing parameters (97ºC/10 min/solute: solvent ratio 1:40) of pectic substances allowed to establish the efficiency of each acid for protopectin solubilization, from 1 up to 750 mMol/L. Two acidic mechanisms were clearly observed. [1] The first, pectin-releasing at low and pectin-degrading reactions at high concentrations and [2] the second, increasingly gravimetric yields reaching values higher than possible, suggesting an attachment of organic groups in the pectic structure. HNO3 was defined as the more interesting acid for pectin extraction.No processamento do suco concentrado de maçã, o bagaço residual da primeira extração é reidratado e prensado novamente a fim de aumentar o rendimento, tornando-se então a matéria-prima para a obtenção industrial de pectina. Neste trabalho os objetivos compreenderam estabelecer os protocolos de beneficiamento do bagaço e de uso de ácidos minerais e orgânicos no rendimento gravimétrico, usando o grau de esterificação, medido por técnicas spectrofotométricas e titulométricas como referencial de qualidade. A farinha de bagaço de maçã, com umidade de 12% apresentava 33,4% de açúcares redutores, e 40% de fibra alimentar e 10-15% de pectina, em base seca, com coloração própria. Os parâmetros do processo de extração das substâncias pécticas, 97ºC/10 minutos e proporção soluto: solvente 1:40 permitiram estabelecer a eficiência de cada ácido na concentração de 1 a 750 mMol/L na solubilização da protopectina. Foram diferenciados dois tipos de comportamentos dos agentes ácidos: [1] liberação de pectina em baixas concentrações e destruição em elevados teores e [2] rendimento gravimétrico crescente, atingindo valores superiores aos possíveis, indicando uma agregação de grupamentos orgânicos na estrutura. O HNO3 foi considerado o mais indicado para a extração de pectina, em concentração máxima de 100 mMol/L