Soft cheese was made from UF milk (retentate) and treated as follows (I)
Rennet (control), (II) Rennet and mesophilic mixed strain culture (Lactococcus lactic
subsp < /em>. cremoris, Lactococcus lactis subsp < /em>. lactis, Leuconostoc mesenteroides subsp < /em>.
cremoris and Lactococcus lactis subsp < /em>. lactis biovar diacetylactis, (III) Rennet and
Streptococcus salivarius subsp < /em>. thermophilus and Lactobacillus helveticus, (IV)
Rennet and S. salivarius subsp < /em>. thermophilus, Lactobacillus delbrueckii subsp.
bulqericus and L. helveticus and (V) Rennet and glucono-delta-Iactone (GDL). All
treatments were fortified with zinc oxide and zinc sulphate at levels of 10 and 20
mg/Kg retentate. sodium chloride (NaC!) was added to all treatments at level of 2%.
The resultant cheeses were stored at 6:!:2°C for 15 days and analyzed for total
solids (T.S). fat, lactose content. titratable acidity. pH value, total nitrogen (T.N).
soluble nitrogen (S.N), salt, ripening indices (formol and shilovich), and organoleptic
properties.
The obtained results revealed that no obvious differences were observed in the
chemical composition of the resultant soft cheese fortified with various sources and
levels of zinc either fresh or during storage. However, the differences were more
clear in pH. acidity and ripening indices.
Sensory evaluation indicated that zinc sulphate was the most suitable source
for zinc supplement with its two ratios. It produced soft cheese having favourite
flavour while fortification with zinc oxide produced soft cheese with unacceptable rusty
taste.
The addition of lactic acid bacteria with rennet is necessary to improve the
organoleptic properties of soft cheese. The results revealed that fortification of soft
cheese with zinc sulphate at levels of 10 or 20 mg Zn/Kg and the addition of
thermophilic bacteria (S. salivarius subsp < /em>. thermophilus and L. helveticus) can be
used to produce good quality soft cheese.