Efficiency of apple juice clarification with using of nano-sized mineral oxides
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Date
2020Author
Sachko, Anastasiia
Kobasa, Igor
Moysyura, O.
Vorobets, Mariia
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Introduction. The aim of presented work was the investigation
of the efficiency of clarification of direct pressing apple juice with
utilization of nano-sized powders of both silicon dioxide and
titanium dioxide, modified silicon dioxide powder in comparison
with bentonite clay.
Materials and methods. The juice used for laboratory testing
was squeezed from "Glory to the Winners" apples. Modified silicon
dioxide powder (AMD-2, specific surface area 280 m2
/g) and nano dispersed powders of both silicon dioxide (specific surface area
300 m2
/g) and titanium dioxide (specific surface area 50 m2
/g) were
selected as clarifiers. For comparison, we used bentonite clay
(specific surface area 160 m2
/g). The optical density was measured
with spectrophotometr, the content of dry substances was evaluated
refractometrically, pH and titratable acidity was determined
according to known methods.
Results and discussion. Prospects of mineral oxides of
titanium and silicon utilization for clarification of apple juice have
been shown. It was established that the most effective clarifiers
were SiO2 powder and suspension. Optimal weight of SiO2 is 2.5 g
per 1 liter of juice; steep time is not more than 24 hours. The form
(in powder or suspension) has no significant effect on the result of
clarification.
The worst clarification ability bentonite clay demonstrated. It
was confirmed that utilization bentonite in suspension form
increases the clarification efficiency. Growth a mass of bentonite
from 0.1 to 2.5 g per l of juice impairs its optical properties.
The effect of temperature of clarification processes on its
efficiency and influence of the “juice-clarifier” contact time on the
physical-chemical properties of the finished product were
investigated. It was shown that the result of clarification is better at
low temperature (4 ºС), and all the used oxides are able to slow
down the flow of natural processes of fermentation of raw apple
materials. It was found that more than 24 hours contact of juice with
clarifiers has a negative influence on the clarification result for all
tested samples.
Conclusion. Nano-dispersed oxides of titanium (IV) and
silicon (IV) could be effectively utilized to clarify of fresh direct
pressing apple juice. Their clarifying ability is higher than bentonite
clay and they could be brought in juice without pre-treatment, in the
form of powder.