Physicochemical, Sensory and Microbial Qualities of Ice Cream Stabilized with Hydrocolloids from Achi (Brachystegia eurycoma) and Ofor (Detarium microcarpum)
Authors: Aremu K. O. , Okonkwo T. M. , Eze C. M. , Agwu C. H. , Agbaka J. I. , Ibrahim A. N. 
Published: June 2020

Aims: To investigate the physicochemical, sensory and microbial qualities of ice cream stabilized with hydrocolloids from Achi (Brachystegia eurycoma) and Ofor (Detarium microcarpum.

Study Design: A 4×5 split-plot in completely randomized design.

Place and Duration of Study: Department of Food Science and Technology, Faculty of Agriculture, University of Nigeria, Nsukka, Enugu State Nigeria between August 2018 and July 2019.

Methodology: Raw seeds of Achi (Brachystegia eurycoma) and Ofor (Detarium microcarpum) were purchased from Ekeonunwa market, Owerri, Imo State, Nigeria and processed into flours. Hydrocolloids from flours of Achi and Ofor were defatted with n-hexane (50 g/250 ml at 26±2°C) dispersed in distilled water (10 g/250 ml), centrifuged (1250 rpm/30 mins and 1500 rpm/30 mins for achi and ofor respectively). The supernatants obtained were dissolved in isopropanol, decanted dried in a hot air oven (60°C, 10 h), pulverised using a blender and stored in air –tight containers. Twenty (20) litres of ice cream samples were produced. Four (4) litres of the mix was measured out as control (i.e. plain ice cream without any stabilizer). Sixteen (16) additional ice cream mixes were produced in the same way by the addition of CMC, achi hydrocolloids, ofor hydrocolloids and a mixture of hydrocolloids from both achi and ofor as stabilizers, each at 0.1%, 0.2%, 0.3%, 0.4% concentrations. The physicochemical, sensory and microbial properties of the ice cream samples formulated were carried out.

Results: The outcome of physicochemical analysis revealed that viscosity (31.65 ± 0.17 cP – 82.50 ± 0.00 cP), overrun (19.30 ± 0.00% - 98.73 ± 0.00%), total solids (24.36 ± 0.33% - 54.00 ± 1.55%) and melting resistance (36.50 ± 0.58% -  92.50 ± 0.58%) were significantly (P < 0.05) affected by the type of stabilizers as well as their concentrations. The total titratable acidity (0.02 ± 0.00% -  0.02 ± 0.00%) and pH (6.74 ± 0.00 - 7.05 ± 0.05) of the ice cream samples showed no appreciable significant (P > 0.05) difference. The overall acceptability (5.80 ± 1.99 - 7.65 ± 1.00), aftertaste (5.45 ± 2.28 – 7.20 ± 0.89), mouthfeel (5.85 ± 1.79 - 7.25 ± 1.37) and homogeneity             (5.20 ± 1.96 - 7.60 ± 1.39) were significantly (P< 0.05) influenced as deduced from the sensory result.

Conclusion: The incorporation of local stabilizers significantly improved the physicochemical, sensory and microbial qualities of ice cream produced. Hydrocolloid extracts of Detarium microcarpum (Ofor), plant-based natural stabilizer is a capable replacer of CMC in ice cream production because of its higher viscosity than other stabilizers and CMC, agreeable consistency, better consumer preference than other stabilizers, enhanced qualities – slow melting rate i.e. high melting resistance, commendable pseudo-plasticity, effectual overrun which will yield more profits for ice cream manufacturers, bring about a new variety of ice creams that are safe for consumption. Hydrocolloid extracts of Detarium microcarpum, at 0.3%, showed more desirable similar effects on the physicochemical, sensory and microbial qualities of ice cream samples formulated compared to CMC and could, therefore be recommended as a replacer of CMC in ice cream production.