Riboflavin, α-tocopherol and retinol retention in milk after microwave heating

Abstract

5ummary-The effect of microwave heating during 2-4 min on the riboflavin, a-tocopherol and retinol content of milk, with three different fat levels, was studied by HPLC. The riboflavin content was not significantiy modified by this treatment. Heating during 2 min did not modify the atocopherol content of whole milk, but in the case of low fat milk, the a-tocopherol content significantly decreased. The effect on the retinol content was less pronounced but still significant (P < 0.05). Further heating (up to 4 min) did not modify the vitamin content in any case. milk 1 microwave heating 1 riboflavin 1 a-tocopheroll retinol Résumé-Rétention des vitamines riboflavine, a-tocophérol et rétinol dans le lait après chauffage par micro-ondes. L'effet du chauffage par micro-ondes, pendant 2 ou 4 min, sur le contenu en riboflavine, a-tocophérol et rétinol du lait entier, demi-écrémé ou écrémé, a été étudié par HPLC. Le contenu en riboflavine n'est pas modifié significativement par ce traitement. Le chauffage pendant 2 min ne modifie pas la quantité d'a-tocophérol du lait entier, mais son contenu diminue significativement dans le lait demi-écrémé. L'effet sur le contenu en rétinol est moins important, mais significatif (P < 0,05). Un chauffage plus prononcé (jusqu'à 4 min) ne modifie plus la quantité des vitamines.

Influence of heating conditions in continuous-flow microwave or tubular heat exchange systems on the vitamin B1 and B2 content of milk

“…I). The milk leaving the oven was either cooled immediately or pumped through insulated Teflon tubing of variable lengths (42.8 cm and 84.17 cm) with an internal diameter of process have no been observed [11,17] however, as in the case of vitamin B 1 , there are no studies about the effect of continuous-flow microwave heating of milk as compared with a conventional unit having the same residence time.…”

“…The objective of the present work was to study the effect of continuous-flow microwave heating of milk at high temperature on vitamin B 1 and vitamin B 2 , and to compare it with a conventional heating process under similar conditions and with the batch microwave heating [11,23].…”

“…As in the case of vitamin B 1 , no studies have been carried out on the effect of continuous-flow microwave heating of raw milk over its vitamin B 2 content. Medrano et al [11] indicated that batch microwave heating of UHT whole milk at 80 °C does not produce significant vitamin B 2 losses. Vitamin B 2 losses were not found after heating commercial pasteurised whole milk at a temperature of 83 °C with a holding time of 4 min [17].…”

Effect of microwave heating on vitamins A, E, B1, B2and B6in milk

“…Like every heat treatment, microwave energy influences the vitamin content: vitamins Bj and B 6 are especially sensitive, vitamins A and E to a lesser extent. The effect of microwaves on the vitamins in milk has been the subject of many recent investigations (Demel et al 1990;Sigman-Grant et al 1992;Brinkmann et al 1993;Sieber et al 1993;Vidal-Valverde & Redondo, 1993;Wagner et al 1993;Medrano et al 1994). No loss of vitamins A, B v B 2 or /^-carotene after microwave heating of milk was found by Demel et al (1990), Medrano et al (1994) or Sieber et al (1993).…”

Physical and Chemical Charateristics of Milk. Variation due to Microwave Radiation

“…1 Valero et al (1999), mentioned the studies carried out on the effect of microwave treatment on different characteristics of milk: foodborne pathogens, 3 vitamins, 4,5 and lactose and whey proteins, 6 enzymes, 7 early Maillard products 8 and cheese making properties. 9 Also, a review covering several aspects of microwave treatment of milk in domestic ovens has been published.…”