Thermal Destruction of Vitamin B6 Vitamers in Buffer Solution and Cauliflower Puree

Abstract

Thermal degradation rates of pyridoxal (PL-HCI), pyridoxine (PN. HCl) and pyridoxamine (PM.2 HCl) in 0.1 M phosphate buffer (pH 7.20) were determined over the temperature range llO-145"C using HPLC procedures. Thermal degradation of PM.2 HCl was modelled by a pseudo-first order rate constant. Thermal degradation of PN-HCI and PL.HCl was modelled by a 1.5 order and second order model, respectively. The temperature dependence of all three rate constants could be described by the Arrhenius equation. None of the degradation products from any of the vitamers exhibited antivitamin activity. Thermal degradation rates of vitamin B6 in cauliflower puree were measured over the temperature range 106-138°C and found not to be described by a rust-order model. The activation energy was markedly lower in this food system than in the model system and emphasizes the importance of conducting experiments on real food systems. The activation energy is in the range reported for several other water soluble nutrients.

Chemical Changes of Vitamins during Food Processing

“…Navankasattusas and Lund (1982) examined the thermal stability of individual vitamin B6 compounds in neutral phosphate buffer solutions and reported, as expected, that PN exhibited the greatest stability. Of interest was the fact that the apparent reaction order for the degradation reaction of each vitamer was concentration dependent and differed depending upon the particular vitamer being studied.…”

“…Activation energy values calculated for the loss of total vitamin B6 following enrichment with either PM, PN, or PL were 23.7, 27.3, and 20.8 kcallmol, respectively. The marked differences in activation energy observed by Gregory and Hiner (1983) and Navankasattusas and Lund (1982) are due presumably to environmental effects of the other ingredients and the fact that the B6 vita- From Gregory and Hiner (1983). a Liquid model systems (pH 7.0) contained potassium caseinate, sucrose, ascorbic acid, and minerals (zinc and iron) and were fortified with individual vitamin B6 compounds.…”

“…d Retorting of cauliflower puree (Navankasattusas and Lund 1982). Calculations based on pseudo-first-order degradation model with rate constants estimated over 1.5 hr heating time.…”

HPLC analysis of vitamin B6 in foods

“…A factor that possibly also diminished the transamination reaction rate in the present study was the lower extraction temperature compared to traditional sample treatments. Thermal destruction of B 6 vitamers at elevated temperatures has been reported by many research groups (Srncova and Davidek 1972, Evans et al 1981, Navankasattusas and Lund 1982, Gregory and Hiner 1983. The catalytic nature of transition metal and aluminium ions in transamination (Snell 1954, Cennamo 1964) could also be reduced by the suggested ion-pairing character of perchlorate anion.…”

Who Would Have Thought? The Story of a Food Engineer

“…We studied kinetics of vitamin degradation (Hamm & Lund 1978, Navankassatusus & Lund 1982, Arabshahi & Lund 1988, Barrett & Lund 1989), enzymes (Ling & Lund 1978a,b;Hyslop et al 1979;Park & Lund 1984;Chang et al 1988), texture (Lund 1982aRao & Lund 1986;Stoneham et al 2000;Sandu & Lund 1985a), and mutagen formation (Pariza et al 1979). Our research included papers on experimental protocol to determine kinetic parameters of constituents in foods (Lenz & Lund 1980).…”