Arkadiusz Szterk

Profiles and concentrations of heterocyclic aromatic amines formed in beef during various heat treatments depend on the time of ripening and muscle type.

Heterocyclic Aromatic Amine (HAA) profiles and concentrations depended on several factors. The largest changes in the HAA profile were observed in meat ripened (chill stored) for 5-10 days. Amines whos concentration varied most prominently included: Phe-P 1, harmane, AαC, IQ, IQx, PhIP, MeAαC, and MeIQx. HAA concentrations were strongly correlated with concentrations of the above compounds. Time of storage significantly affected the HAA profile and concentration. The profile changed dynamically for storage times up to 10 days. For longer times the profile stabilized, only the HAA content increased. A novel, highly precise and accurate HAA analytical method was developed for this study. Results may help to optimize meat processing technology from the point of view of reducing concentration of HAA formed during heat treatment, including the most carcinogenic; IQ, IQx, MeIQx and PhIP amines.

Influence of selected quality factors of beef on the profile and the quantity of heterocyclic aromatic amines during processing at high temperature.

New factors were identified impacting significantly on the formation of HAA during grilling. The number and profile of HAA in grilled beef depend on the fattening system (intensive and semi-intensive), and the effect of the animals sex. The fewest HAAs were formed in rib steak from heifers from a semi-intensive fattening system. A significant effect of storage of meat in refrigerated conditions (5 to 15 days) was also demonstrated on the formation of HAA during grilling. The longer the raw meat was stored, the more HAA was formed during grilling. The quantity of HAA was strongly correlated with the content of free amino acids and a very strong correlation was found with an increasing content of free purine and pyrimidine bases and their nucleosides.

Application of the SPE reversed phase HPLC/MS technique to determine vitamin B12 bio-active forms in beef.

Vitamin B12 is an animal origin nutrient of a substantial importance in human diet. Its concentration in foodstuffs is low and its chemical forms are diverse, which significantly hampers its precise determination. The determination method of choice is HPLC (high performance liquid chromatography) coupled with inductively-coupled-plasma mass spectrometry (ICP-MS). The main disadvantage of this method is high instrumentation cost and complexity of handling. The aim of this work was to develop a novel approach for determination of vitamin B12 bio-active forms in beef and beef liver. The proposed method comprises the following steps: (i) vitamin B12 is cleaved off from peptides using thermal denaturation in a weakly acidic environment; (ii) sample is cleaned-up using liquid-liquid extraction and reversed phase solid phase extraction; and finally (iii) vitamin B12 is determined using HPLC and single-quadrupole mass spectrometer with ESI source. Vitamin B12 concentrations in various beef meats were in the 2.84-3.95 μg 100g(-1) range. Average B12 concentration in beef liver was 153,60 μg 100g(-1) (n = 15). Major forms of B12 present in beef meat include adenosine cobalamin (AdoCbl) and in smaller quantities hydroxycobalamin (OHCbl). Major forms of vitamin B12 present in beef liver include OHCbl (48.2%), AdoCbl (33.8%), methylocobalamin (MeCbl, 16.3%), and cyanocobalamin (CNCbl, 1.7%). Thermal treatment noticeably decreases B12 the content in meat. Depending on conditions of treatment, B12 concentrations in the 1.04-2.20 μg 100g(-1) range were found in processed meats.

Chemical state of heterocyclic aromatic amines in grilled beef: Evaluation by in vitro digestion model and comparison of alkaline hydrolysis and organic solvent for extraction

During grilling of the roast beef the following heterocyclic aromatic amines were found: IQ=200.6 ng 100g(-1), MeIQx=719.8 ng 100 g(-1), MeIQ=532.9 ng 100g(-1), 4.8-diMeIQx=755.4 ng 100 g(-1), norharmane=507.0 ng 100 g(-1), harmane=1952.6 ng 100 g(-1), Phe-P 1=263.7 ng 100 g(-1), Trp-P 2=559.2 ng 100 g(-1), PhIP=1179.8 ng 100 g(-1) and AαC=51.7 ng 100g(-1). Their content was tested by using the method based on alkaline hydrolysis of the sample and the method based on solvent extraction of the grilled meat samples at different temperatures (without hydrolysis). The study showed that the heterocyclic aromatic amines produced during the grilling of beef are in a free form and chemically or physico-chemically bonded. The chemical forms of HAA formed in food have never been studied. For the purpose of the partial confirmation that HAA may be chemically or physico-chemically bonded, grilled beef samples were digested in vitro in model segments of the human digestive tract. Digestive enzymes, particularly proteolytic enzymes caused a statistically significant increase of free HAA determined by using solvent extraction without prior chemical hydrolysis of the sample.

SIMULTANEOUS DETERMINATION OF FREE AMINO ACIDS, L-CARNOSINE, PURINE, PYRIMIDINE, AND NUCLEOSIDES IN MEAT BY LIQUID CHROMATOGRAPHY/SINGLE QUADRUPOLE MASS SPECTROMETRY

A novel approach to single-run determination of 25 free amino acids, L-carnosine, 4 nitrogen bases (purine and pyrimidine), and 5 nucleosides in unpurified biological samples is reported. The analytes were extracted from the sample, derivatized with dansyl chloride, and analyzed using RP-HPLC-DAD-ESI-MS. The reported method features high sensitivity (LOQs in 5–10 ng mL−1 range), wide linearity range with r > 0.94, and high precision (intra-day RSD within the 0.1–4.2% range). Analyte average recovery coefficient was in the 70.1–111.3% range. The method was used to determine levels of free amino acids, L-carnosine, nitrogen bases, and nucleosides in beef (strip loin). Evolution of concentrations of the studied compounds during meat storage processes (vacuum packing, cold storage) was also investigated.

The effect of meat cuts and thermal processing on selected mineral concentration in beef from Holstein-Friesian bulls.

The impact of meat cuts (nine muscles and liver) and thermal processing on selected mineral (potassium, sodium, phosphorus, magnesium, zinc, iron, including heme form) concentration in beef from Holstein-Friesian bulls was evaluated in the present study. The minerals content widely varied depending on the tissue type (skeletal muscles/liver, except zinc) and between the different bovine muscles. The greatest diversity between the muscles demonstrated was zinc (3.5-6.9 mg 100 g(-1)f/w) and iron (1.7-2.3 mg 100 g(-1)f/w), however, there were no significant differences in heme iron to total iron ratio (average 74%). Thermal processes conducted on longissimus dorsi muscles also significantly affected mineral concentration. Grilled, roasted and fried bovine meat was characterised by a higher content (by 6-26%) of most studied minerals (except sodium) as compared to raw meat. Sodium levels in processed meat were 16-33% lower than in raw samples.

Application of semi-permeable membrane dialysis/ion trap mass spectrometry technique to determine polybrominated diphenyl ethers and polychlorinated biphenyls in milk fat.

Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are hazardous food contaminants, their maximum legally allowable levels in food and environment are in the low pgg(-1) range. Therefore some highly selective and sensitive analytical methods must be used to determine them. The 96/23/EC Directive implemented by EC Decision of 12 August 2002 requires recovery rate of an analyte at a concentration below 1 ng g(-1) within the 50-120% range at relative standard deviation (RSD) as low as possible. A method to determine low level PCBs and PBDEs in milk fat based on the semi-permeable membrane dialysis/ion trap GC MS technique was developed. Validation experiments proved that the method performance was within bounds set by the currently standing UE regulations. Recovery rates calculated on the basis of labeled internal standards for majority of the studied indicator PCB congeners and PBDE congeners were close to 100% at RSD below 20%. Also, dioxin-like PCBs recovery rates were compatible with the 1883/2006 EC Regulation (80-120%, RSD below 15%). The developed method turned out to be linear within a far broader concentration range than the studied 0.0025-10 pg μL(-1) range entirely sufficient for analyses of PCB and PBDE in milk fat. Within that range coefficient of linear correlation (R(2)) of calibration curves exceeded 0.98.

Vitamin B12 content in raw and cooked beef

The aim of this work was to evaluate the vitamin B12 content and profile of cobalamin bioactive forms in raw and cooked beef. The study showed that vitamin B12 distribution is unequal among beef muscles. The content of this nutrient ranges from 0.7 to 1.5 μg/100 g of tissue. In beef, three biologically active forms of vitamin B12 were determined, i.e.: methylcobalamin, adenosylcobalamin and hydroxycobalamin; the dominating form of vitamin B12 was adenosylcobalamin (68% of total cobalamins). The process of roasting and grilling had little effect on the vitamin B12 content in the final product as compared to the raw meat. The fried product was characterised by about a 32% lower content of cobalamins than in raw meat.

Seasonal and geographical variations in levels of polychlorinated biphenyls (PCB) and polybrominated diphenyl ethers (PBDE) in Polish butter fat used as an indicator of environmental contamination

The aim of this study was to evaluate the seasonal variation/geographical distribution of environmental concentration of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) across Poland using butter fat as an indicator of the contaminants. The average concentration of six indicator PCBs determined in the studied samples was 1500 pg g–1 fat. The average concentration of 12 dioxin-like PCBs expressed as lower-bound dioxin-equivalent toxicity was 0.684 pg TEQ g−1 fat. The average total concentration of 14 investigated PBDE congeners was 105 pg g−1 fat. Statistically significant concentration differences between summer and winter samples were found. The results of this study indicate also a significant geographical diversification of butter contamination reflecting regional differences in environmental contamination. The seasonal variation of PBDE profiles evidences transformation of PBDE within the environment.

Current Knowledge about Oxysterols: A Review

For years food consumers have been warned that a cholesterol-rich diet may result in atherosclerosis. It is also well known that consumption of large amounts of phytosterols decreases concentration of low-density lipoproteins (LDLs) in blood (LDLs are regarded a key risk factor in development of cardiovascular diseases). However, no scientific evidence has unambiguously proved any direct connection between amount of consumed cholesterol and LDL level in blood. On the other hand, concentration of cholesterol oxidation products, oxysterols, seems to be indeed relevant; for example, they significantly impact appearance of atherosclerotic lesions (plaques). Phytosterols (like sitosterol or campasterol) decrease LDL level in blood, but on the other hand products of their oxidation are toxic. Therefore, it is worth to know influence of phytosterols on living organisms, processes which lead to their formation, and their levels in popular foodstuffs. This paper is an attempt to review literature data on the above aspects, as well as on impact on living organisms of oxidation products of popular sterols.