Volatile and Non-Volatile Components of Beef Marrow Bone Stocks.

Beef bone marrow has been part of the human diet since prehistoric times. Marrow bone stock is important culinary base used by gourmet chefs. It is well known for its distinct savory character in foods. While there has been a great deal published on flavor active components in cooked meats, the flavor composition of bone marrow is still relatively unstudied. For this study, commercial chopped fresh beef marrow bones were simmered in water for seven hours at 90C. Three batches of cooked marrow bone mixtures were prepared. First batch was not enzyme treated. The second and third batch was enzyme treated with papain and umamizyme and heated for one hour at 65C and 50C respectively. All three batches (untreated and enzyme treated) were defatted by microfiltration. Samples from all three batches were heated under pressure at 120C or 160C for one hour. In another series of experiments, the defatted stock samples of three batches (one untreated and two treated with papain or umamizyme) were heated for one hour with ribose, xylose or methyglyoxal. Head space volatiles of all above samples were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS) by Solid Phase Microextraction (SPME). Stock sample prepared at 90C without further treatment showed presence of lipid oxidation products including diacetyl, alcohols, aldehydes and ketones. Stock samples both untreated and treated with enzymes and heated at 120C for one hour showed additionally Strecker aldehydes, dimethyl sulfides and furans. Stock samples treated with enzymes showed in addition pyrazines. Stock samples both untreated and treated with enzymes and heated at 160C for one hour showed all of the compounds identified at 120C heating at higher concentration and fatty acids, thiazoles and alkenals. Samples with addition of methylglyoxal showed significantly higher levels of pyrazines and alkenals. The results of our research showed that after heating and especially after treatment with enzymes and addition of ribose, xylose, and methylglyoxal a number of novel flavor alkenals and interesting volatiles are formed that were not previously identified in bone marrow stocks. All three stock samples were analyzed using Liquid Chromatography-Mass Spectrometry (LC-MS) for non-volatiles mainly amino acids, di- and tri peptides. 20 peptides are identified in the Papain and Umamizyme digested samples. Umamizyme treated stock yielded the most peptides followed by papain treated stock. These non-volatiles act as volatile precursors and generated numerous volatiles when the stocks were treated with ribose, xylose or methylglyoxal.