Article

THE DESIGN OF EXPERIMENTS FOR SHELF LIFE STUDY

Armour Food Research Laboratory. Oak Brook. IL 60521
Journal of Food Science (Impact Factor: 1.79). 08/2006; 40(2):399 - 403. DOI: 10.1111/j.1365-2621.1975.tb02211.x
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    • "Moreover, the shelf life of frozen dough stored under temperature fluctuations must be confirmed by a sensory test. Due to the expense and the timeconsuming nature of sensory testing procedures for food products, the use of staggered sampling designs for shelf life studies in foods has been proposed (Gacula, 1975). The technique consists of evaluating an increasing number of samples as storage time progresses. "
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    • "Also, fitting empirical data to mathematical distributions has lead many researchers to use the Weibull distribution to model the deterioration rate. Among the items whose rate of deterioration was assumed to follow the Weibull distribution are refrigerated meats (Andujar and Herrera [1]), roasted and ground coffee (Cardelli and Labuza [3]), pasteurized milk (Duyvesteyn [7]), luncheon meats (Gacula [8]), breakfast cereal (Pickering [14]), cottage cheese (Schmidt and Bouma [20]), cassava flour (Shirose et al. [22]), corn seed (Tang et al. [23]), frozen foods (Tomasicchio et al. [24]), and ice cream (Wittinger and Smith [25]). Besides food stuff, there are many products, such as camera films, drugs, pharmaceuticals, chemicals, electronic components and radioactive substances that deteriorate while in stock. "
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    ABSTRACT: This paper is concerned with the optimal control of a production inventory system with deteriorating items. It is assumed that the deterioration rate follows the two-parameter Weibull distribution. The continuous-review and periodic-review policies are investi- gated. In each case, optimality conditions are derived. Also, numerical illustrative examples are presented.
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    • "These differences in the logistics of measurement , coupled with proportion of sensory quality loss perceived to be tolerated by consumers, resulted in the adoption of different cut-off indices to mark end of shelf life of foods. On a 7-point scale for measuring off-flavors, a cut-off score of 2.5 was used for one product and a score of 3.5 was used for another (Gacula, 1975). On a 5-point scale for quality, scores of 2 (Randell et al., 1995) and 3 (Piga et al., 2000) were used as markers for product failure. "
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    ABSTRACT: Strained yogurt, labneh, produced by straining cow's milk set yogurt in cloth bags, was stored at 5, 15, and 25 degrees C, and changes in microbial counts, pH, titratable acidity, percentage of free whey, and sensory attributes were monitored during storage. Counts of total aerobes, psychrotrophic yeasts, yeasts and molds, and lactic acid bacteria, except in samples stored at 25 degrees C, increased irrespective of storage temperature. The pH of samples decreased, titratable acidity and percentage of free whey increased, and texture defects were detected at a later stage than flavor changes during storage. Shelf-life data of labneh was adequately described by the Weibull distribution. The nominal shelf life determined using sensory changes and yeast counts as failure criteria ranged from 8.5 to 10.5, 4.7 to 5.8 and 2.3 to 2.7 d at 5, 15 and 25 degrees C, respectively. Q10 (shelf life at T degrees C/shelf life at T+10 degrees C) for flavor quality loss was 1.98 at 5 degrees C, and the corresponding activation energy was 11.3 kcal/mol.
    Journal of Dairy Science 06/2002; 85(5):1023-30. DOI:10.3168/jds.S0022-0302(02)74162-3 · 2.55 Impact Factor
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