Spreads shelf-life

Most matrix reference materials are regarded stable for their application within a certain time frame see also Section 2.2. They are usually produced in large batches designed to ensure that the same material is available for a number of years as well as to spread the high cost of production over as many units as is possible. The stability is closely monitored from initial production by the producer lot numbers or even individual unit numbers are allocated and the producers closely monitor, by regular analysis, the condition and quality of their reference materials over time. Because of such careful control, and to minimize waste, the tendency has been for producers to give a usable life from receipt to the customer, commonly 12-24 months. However, the producers can give this shelf life expectancy only for unopened units. 

Hydrogenation is the catalytically assisted addition of hydrogen to carbon-carbon double bonds. Its main uses are to increase fryer life of oils and shelf life of table oils and bakery products, and to create solids for making shortenings, margarines and spreads, and various confectionery and specialty products. Many process reviews have been published.124 131 Food technologists prefer to minimize the Cl 8 3 content of oils to improve fryer and bot-... 

Low-fat spreads with 40% fat content and containing protein usually have a shelf life of 8-10 weeks and water-based low-fat spreads of about 4 months based on storage at temperatures below 10°C (50°F) (90) (see Section 5.1). Very low fat spreads with fat contents below 20% and with a water continuous emulsion character require low pH, ultra high temperature processing, and possibly aseptic filling procedures to allow closed shelf lives comparable to conventional low-fat spreads (91). 

Is the precise formulation of the product known Often it is not. Kelatively few manufacturers formulate their products from raw materials. The usual situation is for the manufacturer to obtain many, if not all, of the required ingredients from other suppliers. Frequently, a particular ingredient is selected on the basis of its performance and not its chemical composition. In other words, the manufacturer may be interested in adding a material to the product that will allow it to spread more easily, increase shelf life, or improve product stability. The manufacturer has little interest in the formulation of that particular material as long as it performs to his specifications. Furthermore, the supplier may be reluctant to share the formulation of that particular ingredient with anyone. 

The antibiotic Nisin is inhibitory against several grampositive Streptococci, Lactobacilli, Clostridia, Staphylococci and Bacilli (61-62). Goel et al. (63) noted that the addition of Nisin increased the shelf life of low fat dairy spread (Table X). In 20 countries outside the United States, Nisin is permitted as a direct food additive (64), and one major application has been to prevent the growth and subsequent gas production by Clostridia in hard cheese and processed cheese products. In France, for example, Nisin-producing Streptococci have been employed in the manufacture of processed cheese. Nisin has also been studied as a possible alternative to nitrite in the preservation of meats (65). 

This strategy is adopted because of the sheer complexity of the process and the unavailability in the past of suitable sensors for on-line quality moisture content measurement. The quality of the product such as final moisture content, thickness, porosity, wetting, and rehydration capability (for pregelatinized starch) as well as the right crystal structure (the right therapeutic form for pharmaceuticals) are complex functions of drum speed, temperature, nip width, feed material, feed concentration, and feed-spreading technique. In addition, the final moisture content and thickness of the sheet may not be uniform across the width of the drum dryer that can lead to problems in shelf life and packaging of the product, respectively. 

Robens RF, Zottola EA. Shelf-life of pasteurized process cheese spreads made from cheddar cheese manufactured with a nisin-producing starter culture. J Dairy Sci 1993 76 1829-1836. 

The short shelf life of most fruits and the frequent need to store and spread out the surplus of a harvest for a prolonged period of time has brought about a number of processes which provide more durable and stable fruit products. 

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