The effects of controlled atmospheric conditions in the microbial load of African star apple (chrysophylum albidum)

Abstract

This research was carried out to evaluate the effects of controlled atmospheric conditions in the microbial load of two varieties of African star apples (Nwanu and Nwaose).The two varieties (Nwanu and Nwaose) of freshly harvested ripe African star apples were sorted and cleaned by washing for removal of damaged fruits and allowed to drain.  Each variety was divided into two different batches and stored separately in both refrigerated and unrefrigerated conditions. Three different packaging forms were applied to each batch as follows: covered in the absence of oxygen, uncovered and covered. The whole samples were analysed for microbial load both refrigerated and unrefrigerated. The analysis was carried out every three days for the first week and then weekly afterwards until the fruits got spoilt due to entrance of microorganisms. The microbial count increased from [25.5×105 ± 2.71×105 Cfu/ml] to [280.40×105 ± 56.48×105 Cfu/ml]. There was an increase in the Total Titratable Acidity from [2.2619% ± 0.13% anhydrous citric acid] to [1.6218% ± 0.66% anhydrous citric acid] within the same period. The microbial load in Nwaose [108.45x105Cfu/ml ± 103.16 x 105Cfu/ml] was significantly (p<0.005) higher than sweet star  (Nwanu) [102.40x105cfu/ml±104.51x105Cfu/ml].  The microbial load for the samples stored under uncovered ambient temperature was highest [144.36x105Cfu/ml ± 128.40x105Cfu/ml] compared to the refrigerated samples stored in the absence of oxygen [70.14x105Cfu/ml ± 64.84 x 105Cfu/ml]. Control of microbial proliferation using low temperature and anaerobic conditions is important for successful storage of African star apple using controlled atmospheric condition. Hence, Controlled-atmosphere storage is one of the most important innovations in fruit and vegetable storage systems as the composition of gas in the storage affects their storage life.