Effect of particle size on the stability and flavor of cloudy apple juice.

Different particle sizes in cloudy apple juice were obtained following filtration with different mesh sizes (100, 200, 300, and 400-mesh). The effects of cloud particle size on the stability, nutrient content, and volatile flavor of cloudy apple juice were evaluated. With increasing mesh number, particle size decreased (p < 0.05) and particle shape changed. Particle size had an effect on volatile flavor compounds, especially nitrogen oxides, alcohols, and aromatic compounds. The content of pectin and total phenol decreased with decreasing particle size, while the content of soluble protein was not affected. The reduction of cloud particle size increased absolute value of ζ-potential, cloud stability, and apparent viscosity and decreased turbidity and cloud values. Pearson correlation analysis showed that there was a strong correlation between particle size and quality indicators, except for soluble protein.

Zhu D ，Shen Y ，Wei L ，Xu L ，Cao X ，Liu H ，Li J ... -  《-》

Effects of different processing steps on the flavor and colloidal properties of cloudy apple juice.

Flavor loss is a common problem when manufacturing apple juice and is closely related to the properties of the colloidal pectin particles in cloudy juice. The flavor changes and particle properties of three varieties of apple juice ('Ralls', 'Golden Delicious' and 'Fuji') during processing were investigated. Compared with manually pressed juice, juice made by industrial pulping and filtration contained larger particles, resulting in the 'sweet and sour' taste of the juice being relatively weak and the diversity of aromas narrower, as determined by E-nose analysis. Pulping and filtration, however, released some important flavor esters, such as butyl butyrate, hexyl-2-methyl butyrate, and hexyl butyrate. The transformation of volatile compounds during apple juice processing was closely related to the apple cultivar but, in all three varieties, the content of 1-hexanal and (E)-2-hexenal in the juice gradually decreased during processing. Pectinase treatment reduced the colloid particle size and increased the ζ-potential of the juice, resulting in better uniformity and stability, as well as increasing the content of nonanal. After pasteurization, the colloidal particles tended to aggregate and the ζ-potential decreased. Many volatile compounds decreased in concentration or disappeared after heat treatment. The flavor and colloidal properties of cloudy apple juice changed markedly during processing and the effect of each processing step was different. © 2020 Society of Chemical Industry.

Zhu D ，Kou C ，Shen Y ，Xi P ，Cao X ，Liu H ，Li J ... -  《-》

Minimizing quality changes of cloudy apple juice: The use of kiwifruit puree and high pressure homogenization.

Cloud loss, enzymatic browning, and flavor changes are important quality defects of cloudy fruit juices determining consumer acceptability. The development of clean label options to overcome such quality problems is currently of high interest. Therefore, this study investigated the effect of kiwifruit puree (clean label ingredient) and high pressure homogenization on quality changes of cloudy apple juice using a multivariate approach. The use of kiwifruit puree addition and high pressure homogenization resulted in a juice with improved uniformity and cloud stability by reducing particle size and increasing viscosity and yield stress (p < 0.01). Furthermore, kiwifruit puree addition reduced enzymatic browning (ΔE∗ < 3), due to the increased ascorbic acid and contributed to a more saturated and bright yellow color, a better taste balance, and a more fruity aroma of juice. This work demonstrates that clean label options to control quality degradation of cloudy fruit juice might offer new opportunities.

Yi J ，Kebede B ，Kristiani K ，Grauwet T ，Van Loey A ，Hendrickx M ... -  《-》

The potential of kiwifruit puree as a clean label ingredient to stabilize high pressure pasteurized cloudy apple juice during storage.

In the fruit juice industry, high pressure (HP) processing has become a commercial success. However, enzymatic browning, cloud loss, and flavor changes during storage remain challenges. The aim of this study is to combine kiwifruit puree and HP pasteurization (600 MPa/3 min) to stabilize cloudy apple juice during storage at 4 °C. A wide range of targeted and untargeted quality characteristics was evaluated using a multivariate approach. Due to high ascorbic acid content and high viscosity, kiwifruit puree allowed to prevent enzymatic browning and phase separation of an apple-kiwifruit mixed juice. Besides, no clear changes in organic acids, viscosity, and particle size distribution were detected in mixed juice during storage. Sucrose of apple and mixed juices decreased with glucose and fructose increasing during storage. The volatile changes of both juices behaved similar, mainly esters being degraded. Sensory evaluation demonstrated consumer preferred the aroma of mixed juice compared to apple juice.

Yi J ，Kebede B ，Kristiani K ，Buvé C ，Van Loey A ，Grauwet T ，Hendrickx M ... -  《-》

Effect of enzymatic mash treatment and storage on phenolic composition, antioxidant activity, and turbidity of cloudy apple juice.

Oszmiański J ，Wojdylo A ，Kolniak J 《-》