No abstract

Mention of a trade name or proprietary product does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be available.

SUMMARY Investigation of the anthocyan skin pigments in hands 1, 2, and 3 isolated from Vitis vinifera var. Tinta Pinheira grapes showed that the pigments from hand 2 consisted of the 3‐mono‐glucosides of malvidin, peonidin, delphinidin, and petunidin, each acylated with p‐coumaric acid. The pigments from hand 3 consisted of the same four anthocyanins, each acylated with caffeic acid. Evidence is presented to show that the pigments in hand 1 were an artifact obtained under certain experimental conditions, and a tentative explanation for their formation is proposed.

Methods were developed to collect and isolate volatile chemicals produced by aStaphylococcus bacterium in tryptic soy culture that are attractive to protein-hungry adult Mexican fruit flies. Centrifugation of bacteria culture yielded a slightly attractive pellet containing most of the bacteria cells and a highly attractive supernatant. Supernatant filtered to remove the remaining bacteria was as attractive as the unfiltered supernatant. Filtrate at pH 7 and above was much more attractive than filtrate at pH 5 and below. Most of the attractiveness was retained on strong cation exchange media under acidic conditions and eluted with base. Attractive principles could not be trapped on adsorbents such as Porapak Q or extracted with organic solvents from aqueous preparations, but they were easily collected by headspace sweeping with steam. The attractive components were efficiently concentrated by rotary evaporation of steam distillate at pH 5, but at higher pH much of the attractiveness distilled. A reverse-phase HPLC method using a negative counter-ion was developed to separate and collect attractive components of concentrated steam distillate. Attractive fractions collected using this method were concentrated and injected onto silica HPLC. Activity eluted from silica in two distinct bands. Results suggest that the most attractive components of the bacterial odor are highly polar, low-molecular-weight amines.

The bitter components, naringin (in grapefruit) and limonin (in oranges and grapefruit), were quantitated along with pulp, pH, acid, °Brix, oil, vitamin C (ascorbic acid), and color in single-strength and reconstituted concentrated juices packed by the major Texas commercial processors over three seasons. By December, for orange, and by March, for grapefruit, no juice contained more than 6 ppm of limonin. The 3-year mean for oranges was 3 ppm of limonin and for grapefruit 7 ppm of limonin and 585 ppm of naringin (by the Davis test). In both juices, limonin concentration decreased rapidly as the season progressed; naringin concentration remained steady until spring when it began to increase. There was found to be no linear correlation between pulp content of either juice and the concentration of the bitter components. Pulp content of orange juice varied considerably and consistently between plants. The three-year means of vitamin C in grapefruit and orange juices were 31.3 and 43.8 mg/100 mL, respectively.