Banana - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 137

safety at industrial levels, this novel technology can also
be exploited for the enhancement of health promoting com-
pounds for the benefit of consumers (Alothman et al., 2009).

stress reactions of micro-organisms related to hurdle tech-
nology and the prospects of the future goal of a multitarget
preservation of foods. The native microflora of fresh-cut
fruits, which is composed mainly of fungi, is usually sub-
stituted by bacterial strains. Most common antimicrobials
used are sorbic and benzoic acids and sulfite compounds. A
comprehensive review on the influence of handling opera-
tions and storage conditions on the microbiology of lightly
treated fruit products is reported by Brackett (1997). Owing
to their low price and sensory compatibility, citric and phos-
phoric acids are the most used acids to adjust the acidity of
fruits by combined methods. Some of the contaminations
can be avoided by following strict hygienic rules. Others
can be eliminated by disinfection in a bath with 80 ppm
active hypochlorite.
Antimicrobial systems naturally present in plants, ani-
mals, or micro-organisms are extremely appealing for the
public in the context of “natural preservatives.” In partic-
ular, the antimicrobial activities of extracts from several
types of plants used as flavoring agents in food have been
accepted. In addition, in many developing countries, spice
extracts as natural preservatives are preferred to synthetic
antimicrobials because of their availability and cost (Leit-
sner and Gould, 2002). In this context, vanillin, the crys-
talline compound of vanilla pods, can replace sorbic acid
and sulfites against fungi for the formulation of fresh-cut
fruit salads. Moreover, vanillin appears to be very efficient
against yeasts resistant to common preservatives.

Texture change and ethylene production
The use of banana in minimally processed fruit salads has
restrictions due to their high loss of firmness after cutting.
The effects of ascorbic acid (AA), calcium chloride (CC),
L-cysteine hydrochloride (Cis), and Na 2 EDTA, used
in association with modified atmosphere for softening
prevention of minimally processed “apple” banana, were
evaluated (Melo et al., 2007, 2009; Vila-Boas de Barros
et al., 2009). The formulation containing 1% AA, 1%
CC, and 1.5% Cis was the most efficient for avoiding
the softening of minimally processed “apple” bananas.
Ethylene production is stimulated by physical actions used
in the processing of fresh-cut bananas. The accumulated
concentration is sufficient to have an effect on product qual-
ity. Abe and Watada (1991) observed that 2 or 20 μl/liter
ethylene hastened the softening of fresh-cut bananas held
at 20 ◦ C. Abe et al. (1998) studied the influence of cutting
modes on the physiological changes in bananas throughout
storage, thus suggesting that 1-cm-thick transverse section
banana slices produced less ethylene and showed the
lowest respiration rates.
Use of ethylene absorbents prevented the accumulation
of the ethylene and was effective in reducing the rate of
softening in those fresh-cut fruits. A recently developed in-
hibitor of ethylene action, 1-methylcyclopropene (1-MCP),
has been shown to be effective in delaying the ripening of
several preclimacteric fruits. Vilas-Boas and Kader (2006)
evaluated the effect of atmospheric modification, 1-MCP,
and chemicals on quality of fresh-cut banana. Low O 2 (2
and 4 kPa) and elevated CO 2 (5 and 10 kPa), alone or in
combination, did not prevent browning and softening of
fresh-cut banana slices. Treatment with 1-MCP (1 μl/liter
for 6 hours at 14 ◦ C) after processing slowed down soft-
ening and decreased the respiration rate but did not affect
ethylene production and browning of fresh-cut bananas. A
2 min dip in a mixture of 1% CaCl 2 , 1% ascorbic acid, and
0.5% cysteine effectively retarded browning and softening
of the slices for 6 days at 5 ◦ C. Dips including less than 0.5%
cysteine promoted pinking in the banana slices. Higher
cysteine concentrations delayed browning and softening
and maintained higher visual quality for 7 days at 5 ◦ C.

PROCESSING AND PROCESSED PRODUCTS

Preparation operations
Preparation of processed fruit products requires diverse pre-
liminary unit operations. In the case of fruits and vegeta-
bles, enzymatic browning can produce undesirable quality
during handling, processing, and storage. Banana pulp has
high concentrations of PPO and peroxidase, the two en-
zymes responsible for the browning reaction. This reaction
is initiated as a result of tissue disruption and exposure to O 2
during peeling and slicing operations prior further process-
ing. The addition of sodium bisulfate to avoid enzymatic
browning in banana has been widely reported (Guyer and
Erickson, 1954; Tonaki et al., 1973; Garcia et al., 1974).
Blanching to inactive PPO and peroxidase in peeled banana
fruit was discussed by Cano et al. (1990) and Giami (1991).
Additionally, combination of heat treatment and reagents
for banana puree preservation was described, which re-
quired a mild heat treatment plus addition of citric acid and
potassium sorbate (Garcia et al., 1985).

Microbiological alterations
Leistner (2000) reviewed the potential hurdles for foods, the
hurdle effect, and the hurdle technology. However, empha-
sis is placed on the homeostasis, metabolic exhaustion, and