| Permeate is the by-product of the process of ultrafiltration in a kind of cheese making
process in which a semipermeable membrane filters the liquid. It mainly contains
4.5%–4.8% lactose and 0.44%–0.47% mineral salts which make it a safe disposal
issue. This study was conducted to use permeate and its lactose as an alternative
to sugar, and to use these useful permeate compounds in an optimized orange juice
formulation. Milk permeate, as a waste disposal of dairy companies, was applied in
lactose hydrolyzed form as the cost effective sugar and water substitution in production
of orange juice. The RSM optimization method was applied for formulating beverage
mixture. The heated and nonheated permeate samples were incubated with
β-glycosidase enzyme in three thermal ranges (35, 40, and 45°C), 3 time intervals
(60,150, and 240 min), and 3 enzyme levels (0%, 0.1%, and 0.2%). The degree of
hydrolysis was determined by MilkoScan analyzer. In the next step, optimization of
orange juice was accomplished with a mixture of sugar (10%–40%) and hydrolyzed
permeate (10%–40%) with specific Brix through RSM statistical design. The physicochemical
properties and sensory evaluation were measured during 8 weeks of
storage. At the first stage of the study, the heated sample with 0.1% enzyme density,
which was incubated for 150 min at 40°C, was yielded the best result. At the second
stage, which was the juice production and evaluation, the statistical analysis showed
increasing trend of pH and sugar content, but density and vitamin C showed a decreasing
trend during storage time (p < .05). The optimal condition was obtained in
taking 35% permeate and 41 days of storage in which the values of formalin, vitamin
C, and sensory tests were in the highest levels. |