Philip E. Shaw

Terpene hydrocarbons from Psidium guajava

Abstract An extract of whole guava puree, after TLC and GLC, showed the presence of two monoterpenes and nine sesquiterpenes. β-Caryophyllene comprised 95% of this fraction. Possible significance of these hydrocarbons to natural insect attractants and to guava aroma is noted.

2,3-Dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one, a degradation product of a hexose

Abstract Evidence is presented to support 2,3-dlhydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one as the structure of a previously isolated, hexose degradation-pr

Analysis of sweet orange (Citrus sinensis (L.) Osbeck) callus cultures for volatile compounds by gas chromatography with mass selective detector

Volatile constituents of embryogenic and nonembryogenic sweet orange (Citrus sinensis (L.) Osbeck) callus cultures were analyzed by gas chromatography-mass spectrometry to determine if sweet orange flavor essences were produced. Fifteen compounds were identified from the embryogenic callus methylene chloride extracts, with 10 previously reported as volatile constituents of orange juice or peel essential oil, 3 are known fermentation products, 2 have no reported aroma, and 2 were unknown. No volatile compounds were detected from nonembryogenic callus methylene chloride extracts.

Dynamic Headspace Gas Chromatography Combined with Multivariate Analysis to Classify Fresh and Processed Orange Juices

Abstract Sixty-two commercially processed and fresh orange juice samples were analyzed by headspace gas chromatography to quantify 46 volatile constituents in each sample. Computer multivariate analysis was then used to classify these juices into three types based on degree of processing employed. The three types were unpasteurized, pasteurized not from concentrate and reconstituted to single strength from frozen concentrated juice. Principal components (PC) analysis using the first three PCs in a three dimensional graphics plot was the most effective means of classification for these samples. The computer program also provided information regarding the constituents most important to this classification technique. Such classification has potential for use in quality control and in improving quality of processed orange juices.

Volatile Components in Juice from Mandarin and Mandarin Hybrid Fruit

ABSTRACT Twenty-one volatile components of mandarin and mandarin hybrid fruit have been quantified and the amounts were compared to those reported earlier in mandarin and orange fruit.

Volatile constituents of Coccolobo uvifera

Abstract Sea grape pulp was extracted and the extract analysed by gas chromatography-mass spectrometry, resulting in identification of 34 volatile pulp components; these included 20 carboxylic acids, and only two esters and three aldehydes. One volatile component, cyclopentylacetic acid had not been reported earlier as a food component or food flavouring. Components quantified in sea grape pulp were fructose, glucose, sucrose, and ascorbic acid as well as total acid content.

Decreased hydrogen sulphide content in valencia oranges after freeze damage

Abstract The hydrogen sulphide content of headspace gases above freshly extracted Valencia orange juice from freeze-damaged and control fruit was determined. The average value for control fruit was about three times higher than that for fruit suffering moderate to heavy freeze damage, indicating a potential use as an indicator of freeze damage to fresh citrus fruit.

Trapping Volatiles from GLC for Injection into a Mass Spectrometer

In citrus aqueous essences and distilled essence oils, some of the most volatile components are impor tan t contr ibutors to the flavor and a roma of the mixture. 1 However, because of their volati l i ty, they are often the most difficult components to collect in the convent ional manner during gas-liquid chormatographic (GLC) separat ion and to subsequently analyze (by mass spect rometry , for example) wi thout losing the sample in the process. Combined G L C m a s s spectrometers have overcome this difficulty to some extent, bu t there are m a n y occasions when a combined G L C m a s s spect rometer is not available. At t imes it is advantageous to collect volatiles f rom a complex mixture for analysis by mass spectroscopy and to collect less volatile compounds for some other determinat ion (such as infrared) f rom a single GLC run. The technique reported here permits collection of a volatile GLC component using a coiled hypodermic needle as a t rap and subsequent insert ion of the coiled needle into the sep tum of a gas-l iquid sampling sys tem of a mass spectrometer . A min imum of sample handling is required and the sample can be kept at liquid nitrogen t empera tu re until injection into the mass spect rometer is desired. Figure 1 i l lustrates a coiled needle t rap connected through an adapte r to a GLC exit port , an 11 ml Dewar flask for cooling the t rap, and a larger Dewar flask with a top cut f rom a s ty rofoam block for storing

Citrus Essential Oils: Effects of Abscission Chemicals and Evaluation of Flavors and Aromas

Citrus oils are the most important by-products derived from citrus fruits and are primarily used as flavoring, scenting or masking agents for a wide variety of food, beverage, pharmaceutical and perfumery products. Thus, they contribute to the acceptance of many finished products purchased by millions of consumers. Essential oils from citrus have been sold commercially since 1582, when they were listed in the Frankfurt am Main Statutes.