Effect of Radiation and Conventional Processing on the Thiamin Content of Pork

Abstract

erator at 2-5°C overnight (15 hr) prior to enzyme-inactivation. A study was undertal:en to compare the effect of ionizing radiation and thermal processing on the thiamin content of pork. Ground pork was either then rally processed in cans or, after enzyme-inactivation, irradiated in l'ouches with electrons or gamma rays. Thiamin in treated and untre;.ted samples was measured by the thiochrome method. The results ;how that thiamin retention in pork decreases as the irradiation doss increases, but that retention increases as the temperature of irrac.iation decreases. Moreover, irradiation with gamma rays (low dare-rate) leads to lower retention than irradiation with electrons Ihigh dose-rate). Results also show that conventional thermal processing causes loss of thiamin comparable to or greater than irradiation at effective processing conditions for sterilization.The enzyme-inactivation was accomplished in a steam-heated cookhouse, utilizing the cooking cycle shown in Table 1. This process brings the internal temperature of the rolls to the range 75-77'C, at which point, the steam is discontinued to reduce the dry bulb temperature to 74'C when an additional heat treatment of 3 to 4% hr is given to allow each roll to reach an 88% yield. During this time, the internal temperature of the rolls remained 75-77°C. The rolls are then removed from the cookhouse and chilled to 2-5°C by refrigerating overnight.The final steps include cutting and packaging. By removing the end pieces, the chilled pork rolls were trimmed to 45 cm lengths and then sliced into 13 mm sections. For the irradiation, representative samples of each rollwere vacuum packaged in flexible pouches 11.5 x 17.8 cm in size, as described by Killoran et al. (1979).

Effect of Gamma Ray Irradiation and Frying on the Thiamine Content of Bacon

“…This study has confirmed that low-temperature irradiation of bacon results in greater retention of thiamine, similar to that reported by Wilson (1959), and Thomas et al (1981) for minced beef and ground pork, respectively. This study has also identified a protective effect for thiamine when bacon is cooked before irradiation.…”

“…The protective effects of low temperatures for vitamins during irradiation were confirmed by other workers (Diehl 1979;Thomas et al 1981). Diehl (1969Diehl ( , 1975 reported that synergistic effects occurred among irradiation, heating, and storage and the loss of thiamine in wheat flour, crushed oats, and dried whole egg.…”

“…As expected from other studies (Thomas et al 1981), less loss of thiamine occurred when the bacon was irradiated at -40°C rather than at 2°C. Gamma irradiation of raw bacon at 2°C resulted in an exponential loss of thiamine in the product, which agrees with the conclusions of Thomas et al (1981).…”

Effect of Low‐Dose Irradiation and Post‐Irradiation Cooking and Storage on the Thiamin Content of Fresh Pork

“…An observed logarithmic decrease in thiamin with increasing dose suggested that the reaction of thiamin in fresh pork irradiated with increasing low doses was of a first-order nature. Such findings agree with those of Thomas et al (1981), who reported a first-order dependence of thiamin loss on dose level in cooked (76°C) pork lean irradiated at much higher doses (10 to 75 kGy) and lower temperatures (-15°C to -45°C).…”

Chemical Changes After Irradiation and Post‐Irradiation Storage in Tilapia and Spanish Mackerel

“…Jenkins et al (1989) found thiamin losses for raw pork gamma irradiated at 0.57, 1.91, 3.76, 5.52, and 7.25 kGy were 7.7, 23.5, 38.1, 44.8 and 57.6%, respectively, compared to nonirradiated samples. However, losses of some vitamins, including thiamin by irradiation have been considered acceptable when those induced by thermal processing are higher than by irradiation (Thomas et al, 1981).…”