FACTORS INFLUENCING THE STABILITY OF THIAMINE DURING HEAT STERILIZATION^a

Abstract

The effect of heat and certain environmental factors on thiamine stability has been the subject of several comprehensive investigations (2, 3, 8,9,10,12,13, 14,16,17, 18,19). There is good evidence that in pure thiamine solutions the destruction by heat is primarily a hydrolytic cleavage to give pyrimidine and thiazole derivatives (20), and that the reaction rate may be expressed by the conventional equation for a first-order reaction. The effect of p H on the rate of thiamine destruction in pure solutions has been explored (8, 16), with the result that it is well known that thiamine is less stable in alkaline than in acid solutions. Although the stability of thiamine in the presence of extraneous materials, such as foodstuffs, and the more common anions also has been investigated (6, 17), conclusions from this work often have been masked by factors which are only vaguely understood.An expanded knowledge of the factors which influence the stability of thiamine during the sterilization of canned foods is needed by those individuals engaged in developing new food processing methods which might improve the retention of this important vitamin. This is especially true if such information could lead to generalizations in regard to destruction rates at elevated temperatures. Recent descriptions (5, 11, 15) of new processing methods make reference to the markedly improved thiamine retentions which may be realized commercially through the use of high-temperature, short-time processing methods. Some workers ( 5 ) have pointed out that the amount of thiamine destruction during sterilization has been often used as an index to other chemical changes which take place during processing. EXPERIMENTALFour vegetables which are normally processed in large quantities were selected for systematic investigation with regard t o the effect of time, temperature, and other variables which might affect thiamine stability. F o r this purpose, tomato juice was chosen as a typically acid product which requires a relatively mild heat treatment in order to render it sterile. Peas and corn were selected as products which require a relatively intense heat treatment for sterilization, and which represent a high and a low thiamine product, respectively. Lima beans were included because significantly different degrees of retention of thiamine had been previously noted upon processing mature and immature Lima beans in the same retort (71 and 5070, respectively) (4).As a general approach, it was decided that each of these products should be processed over a rather wide temperature range, and that the thiamine content should be determined a t relatively short intervals of time during the course of processing. In order to assure a uniform temperature over substantially all of the time interval of the experiment, all processing was done in small containers (211 x 214 or 208 x OOS), and *Presented a t the Eleventh Annual Meeting of the IFT, New York, N. Y.

Vitamins in brewing: the impact of wort production on the thiamine and riboflavin vitamer content of boiled sweet wort

“…Mashing temperatures were investigated for their effect on the release of thiamine and riboflavin vitamers into the wort. This was performed by adding 50 g of 22 mm ground Pilsner malt to 350 mL of distilled water at varying temperatures (45,55,65 and 72°C) in a 600 mL stainless steel mashing beaker. These mashes were then maintained at their various temperatures for 1 h, while samples were taken and the mashes stirred every 10 min.…”

“…Since malt is the main ingredient after water in wort production it is likely that mashing conditions will greatly affect the solubilization and extraction of these vitamins. It is also likely that the boiling step used to sterilize the wort may lead to a decrease in thiamine content owing its heat instability . Other factors such as the denaturation of proteins (resulting in the liberation and/or destruction of protein‐bound vitamins) at elevated temperatures, the use of processing aids and the addition of hops may also impose either a positive or a negative effect on the final vitamin content of wort.…”

Review: Kinetic parameters for thiamine degradation in foods and model solutions of high water activity

“…5). Bendix et al (1951) showed the effect of high pH on increasing the destruction of thiamine in (Fernandez, 1984). (0) Phosphate buffer+glycerol, a, = 0.95 (Fernandez, 1984). tomatoes and lima beans.…”

Effect of pH and concentration on the chemical stability and reaction kinetics of thiamine mononitrate and thiamine chloride hydrochloride in solution

“…Although this study investigated thiamine stability in simple aqueous solutions at higher thiamine concentrations than are often found in food products, understanding the fundamental reaction mechanisms of thiamine degradation can be used to predict the responses in a variety of food formulations and vitamin supplements. Thiamine has been reported to be more stable in food systems than in buffer systems, and thiamine degradation has been shown to both deviate from and to follow first-order reaction kinetics in food products due to interactions with food ingredients [ 31 , 41 , 45 ]. Regardless of order of reaction, certain components in food are known to affect the stability of thiamine.…”