Agriculture Reference
In-Depth Information
For making nectar from mango puree, 20 -30 Brix puree
is mixed with water and other ingredients (sugar, citric
acid, carboxymethylcellulose—used as stabilizer) and fil-
tered through a finishing screen. Nectar thus prepared is
processed as: (1) vacuum-sealed cans in an agitating retort
at 100 C for 3 min; (2) pasteurized using a plate heat ex-
changer (at 80 C), filled into cans, sealed, and processed
at 80 C for 10 min; or (3) pasteurized using a plate heat
exchanger at 95 C for 1 min and aseptically packaged in
plastic-lined bulk drums (Wu et al., 1993). Nectar viscosity
plays a critical role in the selection of process parame-
ters: time, temperature, initial fill temperature, and so on.
Mango nectars are available with 20-33% pulp content, and
the commercially packed nectar typically contains
ing, cans are processed at 100 C for 20-30 min, followed
by cooling to
40 C. After drying the outer surface of
cans with air jets, cans are labeled and palletized for ship-
ment to the retail markets. Occena-Po (2006) reported that
mango juice is used directly as single strength, blended with
other juices sold as juice blends, or used in fruit smoothies/
shakes.
The enzyme treatment of puree is a critical step in mango
juice production. In addition to the combination and rate
of enzymes used, treatment time and temperature combi-
nation plays a significant role in juice's final consistency.
Vaillant et al. (2001) reported that the enzymes treatment
at 0.14 g/liter at 27 -30 C for 30 min produced the highest
juice yield. These researchers also proposed a microfiltra-
tion process for producing clarified juices and concentrates
from pulp-rich juices (such as mango); this process out-
line is shown in Fig. 15.6. These researchers suggested
the proper enzyme treatment of diluted fruit purees/pulps
can increase the efficiency of membrane filtration process.
Singh et al. (2000) reported that 30 min liquefaction with
1.1 ml enzyme mixture/kg mango pulp is optimal for the
production of clear mango juice following subsequent cen-
trifugation of the serum. Yellowness of pulps during en-
zymatic liquefaction was relatively stable, but the finally
clarified juice became less yellow, showing a greater de-
gree of pigment retention in the pulp. Incubation of en-
zymes added to macerate at 45 C for 6 hours was re-
ported to be optimum for maximum juice yield (Chauhan
et al., 2001).
For the production of juice concentrate, either juice or
puree can be used as the staring material. If concentrate is to
be prepared from puree, treatment with enzymes to break
down pectin and cellulose, followed by centrifugation or
fine-mesh filtration, is necessary. Vacuum evaporation is a
commonly used juice concentration method. Depending on
the intended end use, juice concentrates of variable TSS
contents (28 to 60 Brix) are prepared (Wu et al., 1993;
NMB, 2010). Concentration of fruit juices by membrane
technology is an energy-saving alternative to traditional
processes (Wrolstad et al., 1993) that has not been applied to
mango. Concentration of fruit juices by evaporation or os-
mosis is greatly facilitated by removal of pulp and pectin by
ultrafiltration or cross-flow microfiltration (Johnson et al.,
1996). The permeate could be separately concentrated by
reverse osmosis and added back to the retentate for a fla-
vorful juice concentrate.
Zhang et al. (2008) studied the effects of ultra-HP pro-
cessing (UHP; 500 MPa, 25 C, 20 min) on the volatile com-
pound composition of mango juice. Their results showed
that UHP treatment led to increases in contents of linalool,
<
>
25%
mango pulp (Occena-Po, 2006).
Tribst et al. (2011) evaluated the effect of high-pressure
homogenization (HPH) with heat shock on Aspergillus
niger, vitamin C, and color of mango nectar, which was
processed at 200 MPa followed by heat shock (60 -85 C,
10-20 min). The results of this study showed that A. niger
can be inactivated by applying HPH with heat shock, par-
ticularly as an option to pasteurize mango nectar for the
juice industry.
Argaiz and Lopez-Malo (1996) investigated the effects of
temperature (75 ,80 ,85 ,or90 C) on pectinesterase in-
activation in mango puree and nectar. Their results showed
that the thermal inactivation of pectinesterase in these prod-
ucts required more intensive heat treatment than destruction
of deteriorative micro-organisms; they noted that higher
temperatures led to the development of “cooked flavor,” a
negative sensory attribute. Optimization of sensory quality
of the mango puree and nectar is important with respect to
market success and consumer acceptability.
Mango juice and juice concentrate
Mango puree is the base for mango juice production; puree
can be processed from fresh mangoes (Fig. 15.5) or al-
ready processed puree can be used. Depending on the total
soluble solids (TSS) or Brix level of the final juice (typi-
cally 12 -15 Brix), puree is mixed with water at a predeter-
mined ratio.
The use of pectinase and cellulase enzymes is common
for breaking down pectin and cellulose to maximize juice
yield with optimum viscosity and cloud stability. Enzyme-
treated puree is filtered through finer screens (
0.4 mm).
Addition of 0.4-0.5% citric and/or ascorbic acid is common
to adjust acidity level (Occena-Po, 2006) and to achieve a
desired sugar-acid ratio for optimum flavor and other sen-
sory attributes. Mango juice is heated to 85 C using heat
exchanger and filled into 16-oz or 64-oz cans. After seal-
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