Microbiological Challenge of a Fuzzy Modeled Pineapple Jam

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JUNE, 2014
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Fuzzy logic and reasoning was used to model pineapple jam and to study the trend associated with jam quality change in response to varying imprecise input quantity of three formulation variables: sugar, pectin and citric acid. Sugar/g ranging (100.00-140.00), pectin/g (20.00-30.00) and citric acid/g (0.00-4.00) were combined with 200.00g pineapple pulp at three fuzzy linguistic sets and levels of ‘low’ sugar /g (50.00- 57.50), ‘moderate’ sugar (55.00g-65.00g), ‘high’ sugar (62.50g-70.00g); ‘low’ pectin/g (20.00- 30.00), ‘moderate’ pectin/g (23.00-27.00), ‘high’ pectin/g (26.00-30.00); ‘low’ citric acid/g (0.00-1.50), ‘moderate’ citric acid/g (1.00-3.00) and ‘high’ citric acid/g (2.50-4.00). Twenty seven (27) jam formulations with complex nonlinear physicochemical quality outputs ranges of pH (2.8- 3.18), degree brix of (2.5-8.5), percentage moisture content (46.5-59.35) and texture /mJ(0.288- 8.210) were obtained. The Mamdani Fuzzy Inference System (FIS) was used to process input and output data using the “IF–THEN” rules represented in linguistic variables characterized by continuous triangular membership functions. The Maximum conjunctive aggregation and Centre- of- gravity (Centroid) was used as defuzzifier to predict data at 100% accuracy. The jam formulated with ‘high’ sugar, ‘moderate’ pectin and ‘high’ citric acid was deemed best jam formula with good and quality physicochemical property of ‘low’ pH (2.83), ‘high’ degree brix (7.85oBx), ‘moderate’ texture (4.00mJ) and ‘moderate’ moisture content of 52.5%. A microbial challenge study conducted on the best jam was done to ascertain the ability of the jam to survive microbial contamination. The result suggested that, storing pineapple jam formulated with resultant ‘high’ pH, ‘high’ degree brix, ‘moderate’ texture and moisture content at refrigerator temperature storage conditions can control the growth of spoilage yeast and pathogenic bacteria that may be present in jam products.
A thesis Submitted to the Department of Food Science and Technology, College of Science, in partial fulfilment of the requirements for the degree of Master of Science in Food Quality Management