Chemistry Reference
In-Depth Information
enzymes. Enzymes are processing aids used worldwide for fruit processing, particularly for
the production of clear fruit juice and concentrate. They offer numerous advantages:
Economic
: When added to fruit after crushing, pectinases quickly decrease the viscosity
of the mash by pectin hydrolysis. They facilitate juice extraction from pulpy fruit, increase
press loading and increase juice yield. Residual waste, such as apple pomace, is reduced
and is drier. Enzymes increase the overall productivity of the processing plant. Once added
to the juice, pectinases and amylases hydrolyze residual pectin and starch. Their use is
vital for fast juice clarification, filtration, pasteurization and concentration. As a result,
the juice remains stable, long term, without additives or preservatives, storage volumes
are reduced and shipping weight reduced.
Quality
: Fast juice processing with enzymes lowers the risk of microbial spoilage, reduces
oxidation and improves juice and concentrate shelf life. Pectin hydrolysis of fruit cell walls
weakens cells and vacuoles and thereby maximizes extraction of their components such
as the red colour from berries (anthocyanins), aromas and antioxidants of phenolic type -
known for their positive effect on human health, particularly heart disease prevention.
Sustainability
: The use of enzymes has a positive effect on sustainable production. They
lower energy consumption (electricity, steam and water), reduce waste flow by maximizing
fruit use and reduce dependency on chemicals used in equipment cleaning products.
11.5.1 Apple processing
Worldwide apple production rose from 59.1 mmt in 2000 to 63.5 mmt in 2004.
1
The USDA
calculated 2007/2008 global production at around 42 mmt, with China accounting for 56%
of the total output (23 mmt). China is fast approaching the EU as the world's largest apple
exporter in volume terms with a 19% share market share compared to the EU's 22% in
2007/2008. But its exports' value ranks third behind the EU and market leader, the US.
2
In
2006/2007, 1.42 mmt of apple juice concentrate (AJC) was exported globally, representing
11% of total apple juice production. Volumes almost quadrupled between 2000 and 2007.
Chinese AJC exports in 2006/2007 reached 894 823 tonnes. The same year, EU AJC and
single-strength-juice imports reached 1 mmt in 2006.
5
Apple production in countries such as
France, Germany and Japan is decreasing, while in China, Poland and Russia it is increasing.
11.5.1.1
Apple juice concentrate with press
This classic process is described in Fig. 11.3. Apples are washed, sorted and crushed. At
this stage, mash pectinases are added continuously with a metering pump after dilution in
approximately 10-20 times the volume of water.
The enzymated mash is then pumped into holding tanks. After 30-60 min at ambient
temperature, the mash is pumped into the press. The juice is extracted and immediately
pasteurized for aroma recovery and microbial stability. It can be pre-concentrated at this
stage from 11
◦
to 18-20
◦
brix. It is cooled to 45-50
◦
C and pectinases are added to the
juice. Amylases are added together with pectinases at the start of the processing season
when apples contain starch. After about 2 h, the juice is depectinized and no longer contains
starch. It is then clarified by cross-flow filtration and finally concentrated at 72
◦
brix by water
evaporation, and stored in stainless steel tanks below 10
◦
C.
