No abstract

The pathway for the formation of alkylated pyrazine compounds in amino acid-carbohydrate model systems of low water content was investigated. Radioisotopic labeling studies indicated that sugars were the principal source of the carbon atoms, while amino acids mostly furnished only nitrogen to the pyrazine molecule. Ammonium ions were not the common intermediate through which nitrogen entered the pyrazine ring. Possible pathways for fragmentation of hexoses into twoand three-carbon units and their incorporation into pyrazines were developed.

Biologically active amines are normal constituents of many foods and have been found in cheese; sauerkraut; wine; and putrid, aged, or fermented meats. These low molecular weight organic bases do not represent any hazard to individuals unless large quantities are ingested or natural mechanisms for their catabolism are inhibited or genetically deficient. Tyramine, histamine, and phenethylamine, which can arise from enzymatic decarboxylation of the corresponding amino acids, are strongly vasoactive. Histamine, a capillary dilator, produces hypotensive effects while tyramine and phenethylamine cause a rise in blood pressure. Phenethylamine has been implicated in the onset of migraine headache attacks. The occurrence, mechanism of formation, and catabolism of these compounds is reviewed.

The texture and sweet taste of raw peanuts are changed relatively little during roasting and they contribute significantly to the over-all flavor sensation obtained from roasted peanuts. Roastedn'itty character of roasted peanuts results largely from the reactions of reducing sugars, liberated from sucrose, with free amino acids. The majority of these amino acids are released from a large peptide during roasting. The biogenesis of this peptide and phenylalanine coincides with the maturation process which is necessary for development of good roasted peanut flavor. Biogenesis of sucrose and glutamic acid are positively correlated with maturation only in the latter half of the season. Work in model systems using liC-glucose has shown that many of the pyrazines of roasted peanuts can arise from the glucose, fructose, and free amino acids found in raw peanuts.n 1963 when the authors began work on roasted peanut flavor and its precursors, very little was known about I the subject. Holley (1943, 1952) had studied gases expelled during roasting and found that carbon dioxide and water were the major components expelled while ammonia, hydrogen sulfide, carbonyl compounds, and carbon monoxide were produced in smaller amounts. Hoffpauir (1953) reviewed what was known of raw peanut composition and speculated on the changes that might occur in raw peanuts during roasting. That starch, protein, and fat were important flavor precursors per se appears to have been overspeculation by Hoffpauir in light of present knowledge. The evidence for this conclusion is presented here in some detail.Only a few comments about the flavor of raw peanuts are included in this report. The raw or "beany" nature of raw peanuts disappears upon roasting but the inherent "sweet" character of raw peanuts remains after roasting to contribute considerable sweetness to the integrated flavor response of roasted peanuts. Although raw peanuts are already brittle and "chewy" they become even more so upon roasting. EXPERIMENTAL PROCEDURESDetails of the procedures for extracting the raw peanuts have been published elsewhere (Newell e/ a/., 1967; along with methods for treating the extracts before amino acid. peptide, and sugar analyses were made.Sugars were determined as their trimethyl-silyl ethers (Newell et a/., 1967) and amino acids and peptides were determined using the Beckman Model 120C amino acid analyzer. Peptides 1 and 2 were preparatively chromatographed and collected from the Model 120C analyzer. Larger amounts of peptide 2 were successfully prepared by placing the extracts on a Dowex-1-acetate column and washing the neutral and basic amino acids off the column with water. Elution with 2 N acetic acid removed aspartic and glutamic acid quickly but the highly acidic peptide came off slowly with some difficulty. During this elution apparently some of peptide 2 was converted to peptide 1.Hydrolysis of the peptides was carried out in 6N HCI in sealed borosilicate glass tubes at 110" C. for 12 hours and component amino acids were analyzed on the amino ...

Grapefruits, tangerines and several orange cultivars were evaluated for total and thermostable pectinesterase (TS-PE) activity. Juices were extracted with a Fresh'n Squeeze Multi Fruit Juicer. Variation in total pectinesterase (PE) and TS-PE was not significantly different between cultivars. No significant contribution by traditional quality control parameters (%pulp, ЊBrix, % acid, pH), to total PE or TS-PE was observed. Positive correlations were observed between TS-PE and total PE, when expressed on a pulp (0.669) or soluble solids (0.624) basis.