Characterization of avocado honey (Persea americana Mill.) produced in Southern Spain.

Plant origin, physicochemical parameters and composition were analysed to characterize the avocado honey (Persea americana Mill.) from Andalusia (Southern, Spain). Ashes content, total polyphenol, and electrical conductivity corresponded to these of a typical dark honey (>80 mm scale Pfund). Regarding mineral elements, K was predominant, followed by P and Mg. Antioxidant and invertase activities presented some desirable values. In the 20 analysed samples, 48 pollen types corresponding to 33 families were identified. Avocado pollen was found in high variability (13-58%). At least a 20% was suggested to guarantee the authentic avocado honey. Perseitol, sugar-alcohol identified only in avocado honey, fundamentally contributes to distinguish this kind of honey. The content varied between 0.31 and 1.56 g/100 g. The correlation between perseitol and avocado pollen was found to be significant. A minimum concentration of 0.30 g/100 g of perseitol is suggested to characterize the proposed monofloral avocado honey.

Factors affecting the formation of alkylpyrazines during roasting treatment in natural and alkalinized cocoa powder.

The cocoa roasting process at different temperatures (at 125 and 135 degrees C for 3 min, plus 44 and 52 min, respectively, heating-up times) was evaluated by measuring the initial and final free amino acids distribution, flavor index, formol number, browning measurement, and alkylpyrazines content in 15 cocoa bean samples of different origins. These samples were also analyzed in manufactured cocoa powder. The effect of alkalinization of cocoa was studied. Results indicated that the final concentration and ratio of tetramethylpyrazine/trimethylpyrazine (TMP/TrMP) increased rapidly at higher roasting temperatures. The samples roasted with alkalies (pH between 7.20 and 7.92), such as sodium carbonate, or potassium plus air injected in the roaster during thermal treatment, exhibited a greater degree of brown color formation, but the amount of alkylpyrazines generated was adversely affected. The analysis of alpha-free amino acids at the end of the roasting process demonstrated the importance of the thermal treatment conditions and the pH values on nibs (cocoa bean cotyledons), liquor, or cocoa. Higher pH values led to a lower concentration of aroma and a higher presence of brown compounds.

Study on propolis quality from China and Uruguay.

The composition, bacteriostatic and ROO*-scavenging potential activities of fifteen propolis samples from various botanic and geographic origins were determined to obtain objective information related to propolis quality. Variance analysis showed significant differences (p < or = 0.05) in the contents of polyphenols, flavonoids and active components between fresh and aged propolis. The state of the product (fresh or aged) could be differentiate by using flavonoid pattern and biological activities. A minimum propolis concentration of 80 microg/ml was required inhibit Bacillus subtilis and Staphylococcus aureus while 800 microg/ml was required to inhibit Escherichia coli using fresh propolis. Aged propolis inhibit B. subtilis and S. aureus at concentration of 100 microg/ml and E. coli at 1000 microg/ml. A minimum flavonoids percentage of 18 g/100 g and a maximum ROO*-scavenging potential activity of 4.3 microg/ml were determined in fresh propolis. Flavonoids levels in aged propolis were approximately 20% lower than in fresh propolis. A maximum flavonoids percentage of 19.8 g/100 g and a ROO*-scavenging potential activity between 5.7 to 6.4 microg/ml in aged propolis were quantified. Another objective was to assess the use of ROO*-scavenging potential activity in propolis quality.

Evaluation of Smoky Taste in Cocoa Powder.

The aim of this study was to determine the levels of nine phenols (phenol, guaiacol derivatives, xylenols, and cresols) by using a GC/MS technique in smoked samples under control, commercial samples taken from contaminated batches, and uncontaminated samples. The smoky taste of cocoa powder may have two origins: drying and storage. The sample was steam distilled, extracted with ethyl ether, concentrated, and chromatographed on a 50-m OV-351 fused silica column. The physicochemical data obtained were related to sensory evaluation and submitted to multivariate distribution (Mahalanobis distance) and Pearson Chi-squared test. The discriminatory phenols identified were phenol, 3-methylphenol (m-cresol), 2,3-dimethylphenol (2,3-xylenol), 3-ethylphenol, 4-ethylphenol, and total phenols. The results obtained imply that uncontaminated smoked cocoa samples should have the following maximum concentrations: phenol, 2 mg/kg; 3-methylphenol, 0.9 mg/kg; 2,3-dimethylphenol, 0.55 mg/kg; 3-ethylphenol, 0.90 mg/kg; 4-ethylphenol, 0.70 mg/kg; and total phenols, 9.6 mg/kg.