Effect of Ultrasound and Thermal Pasteurization on Physicochemical Properties and Antioxidant Activity of Juice Extracted from Ripe and Overripe Pineapple

It has become necessary to assess how food processing methods affect qualitative qualities due to the increased consumer awareness of the health benefits of various nutrients in food. In the current study, the effects of ultrasound treatment (37°C, 5 min), pasteurization (90°C, 5 min), and their combination on quality parameters, including pH, total soluble solids (TSSs), titratable acidity (TA), color values (L*, a*, b*), ascorbic acid (AA), total phenolic content (TPC), and antioxidant activity (DPPH), of pineapple juice from ripe and overripe pineapples were assessed. Color values (L*), ascorbic acid (AA), total phenolic content (TPC), and DPPH radical scavenging activity in all juice samples that were sonicated alone and in combination with pasteurization improved significantly (p and color value (a* and b*) decreased in comparison to the control. Whereas pH and acidity did not change significantly (p < 0.05). Pasteurization significantly (p , but sonicated samples significantly (p quality parameters and antioxidant activity, notably in ripe juice. Overall, pasteurization degraded these liquids but sonication, either alone or in combination with it, was advantageous for preserving their quality by retaining nutrients.

Changes in color and rheological behavior of pineapple concentrate through various evaporation methods

The objective of this study was to investigate the effect of various concentration methods namely microwave vacuum evaporation(MVE),microwave heating evaporation(MHE),and rotary vacuum evaporation(RVE)on the concentrate change,the kinetic of color degradation,and the rheological behavior of pineapple juice.The concentrated behavior of pineapple juice from the experimental data of concentration rate was fitted with three types of exponential models for evaluating a suitable prediction.The four-parameter exponential model was found to agreeably explain the concentrated change of pineapple juice during each concentration methods.The Kinetics of color change during concentration processes was evaluated.The color changing from three different evaporations was measured by lightness values(L*),redness values(a*)and yellowness(b*)values,total color difference(TCD)and brown pigment formation index(A420).The result indicated that the change in Hunter parameters,L*and b*,fitted well with the first-order kinetic model while a*,TCD,and Browning index followed the zero-order kinetic model.The observed apparent viscosities(μa)of pineapple concentrate at 55-85℃through the three different evaporation methods were also measured.In relation to temperature and shear rate,the viscosity decreased as these two parameters increased,for all concentrated pineapple juice.On comparing the values ofμa of pineapple concentrate from different concentration methods,pineapple concentrate from MHE has higher values than those from MVE and RVE.The Duncan test,applied to the experimental results,indicates no significant difference in theμa of pineapple juice concentrate by MVE and by RVE.