start earlier in embryo or endosperm. The accumulation of GABA at higher moisture
contents (>50%) reveals its association with germination process instead of stressinduced enzyme while the accumulation of GAMA signals towards the increase
level of expression of stress enzymes “dehydrins” [112, 113]. There is a need to
design such a drying strategy that ensures the firmness of membrane and prohibits
the resulting leaching of nutrients as nutrients are competitors with antioxidant
system in seed and keep the metabolism process well organized [103]. Consequently, the drying method affects the quality of seeds in combination with final
moisture of the seeds as slow drying with low moisture seeds (12%) gives good
germination results.
Since coffee seeds are mechanically damaged during the coffee seed processing
which not only lowers its quality in terms of germination and viability but also with
respect to cup quality, so it is essential to partially cover this topic here by describing
the damage, their causes and remedies, and the available test for identification of
damaged seeds as detail description of this issue is beyond the scope of this review.
Pulping is process of removing exocarp and endocarp to produce the seeds with
parchment friction and attrition. Removal of pulp and parchment by peeling
machines and palette scarifier, respectively, lowers the viability and germination
and viability of seeds than unharmed seeds due to rupture of sensitive seed cell by
external applied pressure, high drying temperature, and coffee seed borer. Due to
high cost, labor requirement, and operational complexities, previously used tetrazolium test to determine mechanical damage has been replaced by the nondestructive
LERCAFE test by immersing the seeds in cost-effective sodium hypochlorite. The
least effective concentrations of sodium hypochlorite are 2.5% for seeds without
parchment and 5% for seeds with parchments for 3 h at 35
C, whereas slight higher
concentration (3.5%) can also be used to lessen the time from 3 to 2 h. This test also
has the capacity to distinguish the various kinds of mechanical damages. The
occurrence of green stain in endosperm is symbol of high temperature drying,
whereas a depression surrounded by a green ring is a sign of damage by coffee
seed borer. However, sometimes the results of LERCAFE showed inconsistencies
over seeds viability and germination results that is due to long period immersion
(>5 h) of seeds in solution or pathogen infestation in endosperm of seed lots,
whereas active chlorine usually reacts with the tissues of embryo to denote tissue
damage by its coloration due to which LERCAFE showed superior results [115].
Since sodium hypochlorite is photo and thermo sensitive and contains a certain
amount of active chlorine (almost 10% for commercially available), so its standardization by quantifying its active chlorine and immersion duration is very important
for credible commercial applications. Sodium hypochlorite solution with 2% active
chlorine contents and immersion period less than 5 h and more than 1 h found to be
appropriate for viability and germination determination. The higher or lower treatment time and active chlorine contents than recommended may lead to extra or
under-coloration of embryo tissues giving us a wrong clue about the viability and
germination. However, activity of the active chlorine influences the certain antioxidant system of seeds too. The activity of esterase, esterase isoenzyme, and catalase
found to be decreased or diminished, while the activity of superoxide dismutase and
662
A. Hameed et al.
contents (>50%) reveals its association with germination process instead of stressinduced enzyme while the accumulation of GAMA signals towards the increase
level of expression of stress enzymes “dehydrins” [112, 113]. There is a need to
design such a drying strategy that ensures the firmness of membrane and prohibits
the resulting leaching of nutrients as nutrients are competitors with antioxidant
system in seed and keep the metabolism process well organized [103]. Consequently, the drying method affects the quality of seeds in combination with final
moisture of the seeds as slow drying with low moisture seeds (12%) gives good
germination results.
Since coffee seeds are mechanically damaged during the coffee seed processing
which not only lowers its quality in terms of germination and viability but also with
respect to cup quality, so it is essential to partially cover this topic here by describing
the damage, their causes and remedies, and the available test for identification of
damaged seeds as detail description of this issue is beyond the scope of this review.
Pulping is process of removing exocarp and endocarp to produce the seeds with
parchment friction and attrition. Removal of pulp and parchment by peeling
machines and palette scarifier, respectively, lowers the viability and germination
and viability of seeds than unharmed seeds due to rupture of sensitive seed cell by
external applied pressure, high drying temperature, and coffee seed borer. Due to
high cost, labor requirement, and operational complexities, previously used tetrazolium test to determine mechanical damage has been replaced by the nondestructive
LERCAFE test by immersing the seeds in cost-effective sodium hypochlorite. The
least effective concentrations of sodium hypochlorite are 2.5% for seeds without
parchment and 5% for seeds with parchments for 3 h at 35
C, whereas slight higher
concentration (3.5%) can also be used to lessen the time from 3 to 2 h. This test also
has the capacity to distinguish the various kinds of mechanical damages. The
occurrence of green stain in endosperm is symbol of high temperature drying,
whereas a depression surrounded by a green ring is a sign of damage by coffee
seed borer. However, sometimes the results of LERCAFE showed inconsistencies
over seeds viability and germination results that is due to long period immersion
(>5 h) of seeds in solution or pathogen infestation in endosperm of seed lots,
whereas active chlorine usually reacts with the tissues of embryo to denote tissue
damage by its coloration due to which LERCAFE showed superior results [115].
Since sodium hypochlorite is photo and thermo sensitive and contains a certain
amount of active chlorine (almost 10% for commercially available), so its standardization by quantifying its active chlorine and immersion duration is very important
for credible commercial applications. Sodium hypochlorite solution with 2% active
chlorine contents and immersion period less than 5 h and more than 1 h found to be
appropriate for viability and germination determination. The higher or lower treatment time and active chlorine contents than recommended may lead to extra or
under-coloration of embryo tissues giving us a wrong clue about the viability and
germination. However, activity of the active chlorine influences the certain antioxidant system of seeds too. The activity of esterase, esterase isoenzyme, and catalase
found to be decreased or diminished, while the activity of superoxide dismutase and
662
A. Hameed et al.