Stabilization of guava nectar with hydrocolloids and pectinases

Abstract

ObstractThe aim of this study was to stabilize guava nectar using hydrocolloids and/or enzymes, and evaluate the stability and the bioactive compounds content during storage. In general, there was a decrease in pH and an increase in titratable acidity and soluble solids of the nectars. During storage, it was observed that nectars with pectinase showed decrease in pH, increase in titratable acidity and soluble solids, and also less phase separation, standing out among them the nectar with enzyme and guar gum. The nectar formulated with xanthan showed the highest antioxidant capacity. All nectars showed slight decrease in the carotenoid content and high losses of vitamin C during the storage period.

Ultrasound‐assisted homogenization and gum Arabic combined to physicochemical quality of cupuaçu juice

“…The soluble solids contents (Figure c) did not vary significantly ( p > 0.05) during storage for all treatments. For guava nectars stabilized with different hydrocolloids (Krumreich et al, ), the authors also did not observe a significant reduction of soluble solids content during storage. This small reduction may be associated with microbial growth (even with the addition of potassium sorbate) in juices in which the microorganisms consume macronutrients for their development and growth.…”

“…pH is an important parameter for microbial growth and may favor the stability of vitamins such as ascorbic acid (Krumreich et al, ). Samples of cupuaçu juice (Figure a) showed pH values in the range of 4.38–4.64.…”

“…Titratable acidity is an important physicochemical parameter for fruit juices as it may be related to the sensorial acceptance of the consumer (Krumreich et al, ) . Note that titratable acidity (Figure b) increased significantly ( p < 0.05) for all treatments.…”

“…This behavior is not observed for cupuaçu juices because the pH remains stable. One possible explanation is that the compounds present in the juice may behave as a buffer solution (Krumreich et al, ). The variation of titratable acidity may be related to the formation of ions during the sonolysis process of water or bioactive compounds as well as of byproducts generated by oxidative degradation during storage.…”

“…The treatments presented ascorbic acid stability throughout the storage. This stability may be related to no change in pH during storage (Figure ) since ascorbic acid is more stable at lower pH (Krumreich et al, ). The higher concentration of ascorbic acid for the combined US and GA treated juices can be explained by the greater release of intracellular ascorbic acid caused by ultrasonic processing and the complex adsorption between ascorbic acid and GA, leading to physical entrapment, encapsulation, hydrogen bonds, and any other specific or nonspecific binding of bioactive compounds molecules (Mirhosseini, Tan, Hamid, & Yusof, ).…”