Avocado - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 435

processing (HPP) is being used nowadays in commercial
products. Unlike thermal processing and other preservation
technologies, HPP effects are uniform and nearly instan-
taneous throughout the food and thus independent of food
geometry and equipment size. Palou et al. (2000) studied
the effect of continuous or oscillatory HPP treatments on
PPO and lipoxygenase (LOX) activities, standard plate,
yeast and mold counts, sensory acceptability, and instru-
mental color in guacamole. Significantly less residual PPO
and LOX activities were obtained with increasing process
time and number of pressurization-decompression cycles.
The lowest residual PPO activity value (15%) was obtained
after four HP cycles at 689 MPa with a 5 min each holding
time. Standard plate as well as yeast and mold counts of
HPP guacamole were

that are beneficial to human health. Eating avocados has
been shown to reduce cholesterol and the risk of atheroscle-
rosis. Avocado has also been used in the treatment of os-
teoarthritis, and some studies are suggesting use of this fruit
in cancer prevention diets. In addition, the by-products of
avocado (seeds and leaves) are rich sources of specific phy-
tochemicals with a potential use as therapeutics. The main
challenges for the development of stable products of avo-
cado are its high browning potential and relatively high pH.
Success of minimally processed avocado products requires
strictly following GMPs, a HACCP program, and adding
efficient antioxidants. To achieve longer shelf life of avo-
cado, freezing and hurdle technologies have been applied
with varying success. Newer processing technologies in-
clude high-pressure operations to produce guacamole-type
products and cold expression to obtain avocado oil. The de-
velopment of more efficient equipments will help scale-up
of emerging processes to preserve the sensorial, nutrimen-
tal, and health-beneficial properties of avocado.

10 cfu/g. Sensory acceptability and
color of HPP guacamole were not significantly different
from untreated guacamole; one of the major advantages of
HPP was minimal loss of volatiles thereby preserving the
aroma and flavor. In the case of HPP, with no additional
thermal sterilization, the lowering of avocado pulp pH
to safer values (

<

4.5) may contribute to decrease the
microbial risk but may affect the green color.
Another example of innovation in the preparation of gua-
camole is a patented method reported by Griebel and Kargel
(2008), which consists of immersing pitted peeled avocados
in an alkaline solution having a pH higher than 8. The av-
ocado halves are then heated to a temperature high enough
to inactivate the native enzymes. The treated avocados are
used in preparing guacamole, adding acid, onion, and gar-
lic; an antioxidant and/or glycerol are also added sometime.
The prepared guacamole is then consumed fresh, refriger-
ated, or canned in jars.
Another alternative to process avocado may be the high
temperature short time processing (HTST), which will de-
liver food of a higher quality than canning but requires rapid
heat transfer to the material; one problem remaining is the
time required to cool the food down after heating due to
thermal conduction being potentially too slow (Fryer and
Versteeg, 2008).
Dorantes and Ortiz (2008) patented a procedure to obtain
low-calorie avocado paste by preextracting about half of the
oil. The main operation is a rapid heating of the pulp using
microwaves to inactivate enzymes and vegetative bacteria
as well as release part of the oil. The brilliant green color
and most of the beneficial components of the avocado are
retained in both the low-calorie paste and the oil.

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ACKNOWLEDGMENTS
The authors want to acknowledge CONACYT Mexico
scholarship 239383 and Instituto Polit ´ ecnico Nacional
projects SIP-20110813 and SIP-20110788.

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SUMMARY
Avocado fruits present the extraordinary characteristic of
having high, good lipid content, which make them a source
of water- and lipid-soluble nutrients and phytochemicals