PRELIMINARY STUDIES ON STABILIZATION OF THIAMIN IN DEHYDRATED FOODS 1

The problems of transportation and meat shortage associated with the lend-lease program of the recent war have given an impetus to research studies on dehydrated meats. Since the nutritional investigations on dehydrated meat have been of such recent date, few reports have appeared in the literature.The report here presented includes studies initiated in 1943 on the effects of temperature, container, and incorporation of soya flakes on the niacin, riboflavin, and thiamin contents of dehydrated pork loaves during storage. Rice, Beuk, and Robinson (1943) reported that dehydrated pork retained little thiamin after several weeks' storage at 48.9"C. (120'F.) and that the thiamin could be stabilized to an appreciable extent by the inclusion of a mixture consisting of cereals, milk, tomato paste, and bone meal. The unsupplemented product retained 15 per cent of the original thiamin after one week's storage at 120°F., as compared with a 74 per cent retention of thiamin in pork supplemented with non-meat solids to the extent of 33 per cent. I n later studies, Rice and Robinson (1944) indicated further that at temperatures up to 37.ZoC.(99OF.) there is little or no loss of niacin or riboflavin over a period of 219 days. Thiamin decreases more rapidly, showing some loss at 26.7"C.(8OoF.). After 219 days' storage the thiamin retention in dehydrated pork is 29 per cent, while at higher temperature there is almost complete destruction of thiamin. Rice, Beuk, Kauffman, Schultz, and Robinson (1944), in their preliminary studies, have shown that dehydrated pork and dehydrated eggs stored at or above temperatures of 37°C. (98.6'F.) lose thiamin more rapidly than certain other foods, such as dried skim milk and cereals. Dehydrated mixtures of 67 per cent pork and 33 per cent cereals or milk solids lose thiamin much less rapidly than dehydrated pork alone. The thiamin loss of the dehydrated pork was €ound to be somewhat related to the moisture level over the range of 0 to 6 per cent. Thiamin retention was not affected by storage in vacuum, nitrogen, or carbon dioxide rather than air.Products rich in carbohydrate material were shown to be the most effective stabilizing agents studied. The authors postulated that the sta-

Section: Resultssupporting

confidence: 92%

“…Rice, Beuk, and Robinson (1943) reported that dehydrated pork retained little thiamin after several weeks' storage at 48.9"C. (120'F.)…”

mentioning

confidence: 98%

NIACIN, RIBOFLAVIN, AND THIAMIN STUDIES ON DEHYDRATED PORK LOAVES ¹

Nymon

Gortner

1947

“…However, a critical review of literature produced several instances where this generalization, at intermediate or high a,, may not be valid and rate of thiamin degradation as a function of a,,, goes through a maximum. Rice et al (1944) reported a study on dehydrated pork held several days at 49°C at 0, 2, 4, 6, and 9% moisture. Pork at 6% moisture content showed greater losses of thiamin than that at 9%.…”

Section: Introductionmentioning

confidence: 99%

Thiamin Stability in Simulated Intermediate Moisture Food

Arabshahi

Lund

1988

Four different intermediate moisture model systems (IMMS) were designed and prepared to simulate intermediate moisture foods. Stability of thiamin hydrochloride in IMMS as a function of temperature, oxygen, a,, moisture content and composition of the model systems was studied. Analysis of kinetic data indicated that the rates of degradation of thiamin (1) can be represented by a first order model, (2) were not affected by oxygen concentration and presence of riboflavin and niacin, (3) obeyed an Arrhenius relationship for temperature dependence in the range 25-60°C (4) increased as polarity of the reaction medium decreased, and (5) decreased as a, increased from 0.65 to 0.85. INTRODUCTIONSEVERAL INVESTIGATORS have reported that moisture content or water activity (a,,,) influences the thermal stability of thiamin in food (Dennison et al., 1977; Farrer, 1955). In general, an increase in a, decreases thermal stability of thiamin in dry and dehydrated food. However, a critical review of literature produced several instances where this generalization, at intermediate or high a,, may not be valid and rate of thiamin degradation as a function of a,,, goes through a maximum. Rice et al. (1944) reported a study on dehydrated pork held several days at 49°C at 0, 2, 4, 6, and 9% moisture. Pork at 6% moisture content showed greater losses of thiamin than that at 9%. Dennison et al. (1977) reported the rate of thiamin degradation in a model system at 45°C as a function of a,. The first-order rate constants exhibited a maximum at an a,,, between 0.4 and 0.65. For flour, Herrmann and Tunger (1966) recognized a maximum rate of thiamin destruction around a moisture content of 13%. Herrmann et al. (1978) found maximum thermal destruction of thiamin in freeze-dried meat at a moisture content of nearly 30% dry basis (db). In these two instances, the presence of maximum rate was explained by the hypothesis that the browning reaction is a major pathway for thiamin loss and that the rate of degradation for thiamin should show the same a,., dependence as the rate for browning reaction. However, they did not prove their hypothesis. Currently, there is no satisfactory explanation for the observation of a maximum rate for thiamin degradation as a function of a, or moisture content.There are conflicting reports on the effect of oxygen on thiamin degradation. Farrer and Morrison (1949) reported that oxygen can accelerate thermal destruction of thiamin in buffer solution at temperatures greater than 70°C. Williams and Spies (1938) and Mulley et al. (1975) concluded that destruction of thiamin was not oxidative. On the other hand, Sabri et al. (1968) claimed that oxygen affected the order of thiamin degradation reaction. Because of conflicting reports on thiamin stability, this research was initiated on the thermal destruction of thiamin as a function of a,, types of humectant, oxygen level, and presence of niacin and riboflavin.

“…Thus there was considerable loss of thiamin during dehydration but the loss did not exceed 50 per cent except in the case of Plant C. All the samples from this plant were consistently low in thiamin. Rice and Robinson (1944) reported a retention in the dehydrated meat of 63 per cent of the thiamin originally present in the raw meat. Since fresh pork contains about 87 of folic acid per 100 g a .…”

mentioning

confidence: 99%

“…The dry-matter content of these samples was about twice that of fresh pork [McIntire et al (1943) ; Greenwood, Kraybill, Feaster, and Jackson (1944) ; Rice and Robinson (1944) 3 but the dry matter consisted of more protein and less fat than that of fresh pork. The values for protein and fat fall within the same range as those given by Rice and Robinson (1944) for dehydrated pork. If there had been no loss of vitamins during processing the vitamin content should have been two to three times that of fresh pork.…”

mentioning

confidence: 99%

VITAMIN CONTENT OF DEHYDRATED MEATS¹

Whitmore

Pollard

Kraybill

et al. 1946

Large quantities of meat have been dehydrated during the war period. Many of these products have been stored for considerable periods of time or shipped over long distances. It is important, therefore, to know not only the composition of the meat shortly after processing but to follow the retention of the vitamins during storage.This study has been limited largely to the proximate composition and the thiamin, riboflavin, and niacin content of commercial samples of dehydrated pork and corned-beef hash immediately after production and after definite periods of storage. A few folic acid and biotin determinations have also been included. EXPERIMENTAL PROCEDUREThe samples were collected in Chicago by workers at the University of Chicago where the proximate analyses, thiamin, and some of the riboflavin determinations were made. Aliquots were taken from each sample and sent to the University of Wisconsin for the other analyses.Proximate analyses were made according to Methods of Analysis, fourth edition, of the Association of Official Agricultural Chemists.Thiamin-method of Hennessy (1942). Riboflavin-method of Snell and Strong (1939) at Wisconsin and Peterson, Rrady, and Shaw (1943) at Chicago.The samples for microbiological assay were hydrolyzed with 50 C.C. of 0.1 N HC1 at 15 pounds pressure f o r 20 minutes and cooled, after which two grams of papain dissolved in five C.C. of 2.5 M sodium acetate were added and the mixture incubated at 37" C. (98.6"F.) overnight under toluene. This digest was then neutralized, filtered, and extracted by shaking with ether and the aqueous solution made to volume, according to McIntire, Schweigert, Henderson, and Elvehjem (1943 ) .Niacin-samples prepared and assayed according t o the procedure of Krehl, Strong, and Elvehjem (1943). Biotin-method of Shull, Hutchings, and Peterson (1942) with the modified medium reported by Shull and Peterson (1943). The samples were hydrolyzed by autoclaving with 4 N sulfuric acid for two hours at 15 pounds pressure.Folic acid-samples assayed for X. faecalis activity against a standard of solubilized liver and the results were then expressed in terms of vital