Changes in the physicochemical properties, aromas and polyphenols of not from concentrate (NFC) apple juice during production

Abstract

The effects of unit operations on the quality of not from concentrate (NFC) apple juice were investigated in this study. After the main processing steps (juicing, pre-pasteurization, homogenization and pasteurization), juice samples were collected and characterized by total soluble solid (TSS), titratable acidity (TA), pH, turbidity, non-enzymatic browning index (NEBI), color quality, aromas and phenolic constituents. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied for analyzing juice aromas and polyphenols. The results showed that homogenization only affected (increased) the juice turbidity, and only the TSS content was not affected by the unit operations. The TA, pH, aroma component and polyphenol content of the NFC apple juice were significantly decreased, while the turbidity, NEBI and color values were significantly increased by pre-pasteurization. Pasteurization had less effect on these properties than pre-pasteurization. Therefore, those were the thermal treatments that mainly affected the juice quality during NFC apple juice production.Cambios en las propiedades fisicoquímicas, aromas y polifenoles durante la producción de jugo de manzana no procedente de concentrado (NFC) RESUMENEl presente estudio investigó los efectos detectados en las unidades de producción de jugo de manzana no procedente de concentrado (NFC). Después de realizarse los principales pasos del proceso (extracción, prepasteurización, homogeneización y pasteurización), se recogieron muestras que fueron caracterizadas a partir de la presencia de sólidos solubles totales (TSS), la acidez valorable (TA), el pH, la turbidez, el índice de oscurecimiento no enzimático (NEBI), la calidad de color, el aroma y los componentes fenólicos. Para valorar el aroma del jugo y la presencia de polifenoles se llevó a cabo un análisis de componentes principales (PCA) y un análisis de clúster jerárquico (HCA). Los resultados confirmaron que la homogeneización solo afectó la turbidez del jugo, aumentándola, siendo el contenido de TSS el único aspecto no afectado por la unidad de producción. La TA, el pH, el componente de aroma y el contenido fenólico del jugo de manzana NFC se redujeron significativamente, mientras, debido a la prepasteurización, se registraron aumentos en la turbidez, el NEBI y los valores de color. La pasteurización tuvo menos efecto en estas propiedades que la prepasteurización. Por lo tanto, se concluye que, durante la producción de jugo de manzana NFC, la calidad es afectada principalmente por los tratamientos térmicos. ARTICLE HISTORY

Physicochemical properties and antioxidant activity of two varieties of apple cultivated in different areas in Morocco

“…The obtained results for pH are comparable to those documented for some fruits such as orange, kiwi fruit and apple 23 , which ranged from 3.23 to 4.22. Similar findings have been published for the apple in Poland, Tunisia and China respectively [24][25][26] . The results of TA from this study were higher than those documented by Boudabous et al 24 but similar to those reported previous studies 23, 26 .…”

“…Similar findings have been published for the apple in Poland, Tunisia and China respectively [24][25][26] . The results of TA from this study were higher than those documented by Boudabous et al 24 but similar to those reported previous studies 23, 26 . Acidity is one of the elements used to assess fruits quality 27 , and it gives the sour taste due to the presence of malic acid…”

Using a red‐fleshed and six varieties of thinned young apple to make juice and their phytochemicals characterization

“…The increased L * value after thermal treatment was also observed in previous studies (Tian et al., 2018), providing the juice with brighter color and more transparent appearance. The explanation is that steaming treatment accelerated the clarification of the juice by changing their macromolecules distribution.…”

“…The pH value of the TYA juice was not significant affected or slightly increased by the steaming treatment. Fruit juice is regarded as common natural buffer system containing a great number of organic acids, which provide juice with a resistance to pH change (Tian et al., 2018). However, heat treatment juices were detected lower titratable acid (TA) content and total phenol content possibly due to the thermal degradation.…”

Phenolic Compounds from Apples: Reviewing their Occurrence, Absorption, Bioavailability, Processing, and Antioxidant Activity – a Review

“…Pavun et al [2018] highlighted that the use of fruit nectar definitely lowered the phenolic content in commercial juices, which was ultimately correlated with their antioxidant activity. It was also demonstrated that not pasteurization but pre-pasteurization had a significantly stronger impact on phenolics content during processing of not from concentrate (NFC) juices [Tian et al, 2018].…”