@article{emenhiser_watkins_simunovic_solomons_bulux_barrows_schwartz_1999, title={Packaging preservation of beta-carotene in sweet potato flakes using flexible film and an oxygen absorber}, volume={22}, ISSN={["0146-9428"]}, DOI={10.1111/j.1745-4557.1999.tb00927.x}, abstractNote={ABSTRACT Sweet potato flakes are potentially an affordable, shelf‐stable source of provitamin A β‐carotene. Because β‐carotene is susceptible to oxidative degradation, particularly in dehydrated food materials exposed to atmospheric oxygen, several packaging conditions were evaluated for enhancement of β‐carotene retention in sweet potato flakes during storage. The flakes were packaged in either a polypropylene film (high oxygen permeability) with air headspace or a nylon laminate film (low oxygen permeability) with air headspace, under vacuum, or with an Ageless oxygen absorber sachet enclosed. Packaged flakes were stored in the dark at ambient laboratory temperature (∼23C), and β‐carotene content was determined at intervals from 0 to 210 day storage using reversed‐phase liquid chromatography. Among the packaging conditions tested, β‐carotene retention was enhanced incrementally as the apparent availability of oxygen was reduced (nylon > polypropylene; oxygen absorber > vacuum > air headspace). The combined use of oxygen absorbers and flexible oxygen barrier film gave excellent retention of β‐carotene during the 210 day trial.}, number={1}, journal={JOURNAL OF FOOD QUALITY}, author={Emenhiser, C and Watkins, RH and Simunovic, N and Solomons, N and Bulux, J and Barrows, J and Schwartz, SJ}, year={1999}, month={Mar}, pages={63–73} }
 @article{emenhiser_englert_sander_ludwig_schwartz_1996, title={Isolation and structural elucidation of the predominant geometrical isomers of alpha-carotene}, volume={719}, ISSN={["0021-9673"]}, DOI={10.1016/0021-9673(95)00713-X}, abstractNote={The recent development and application of a polymeric C30 stationary phase have given unique separations of cis-trans carotenoid isomers in reversed-phase (RP) liquid chromatography (LC) owing to the exceptional shape selectivity of this stationary phase. In the present research, several geometrical isomers of alpha-carotene were at least partially resolved from a photo-isomerized mixture when chromatographed on a 3-microns polymeric C30 column. Double bond configurations of the five predominant alpha-carotene peaks, as isolated on a semi-preparative C30 column, were unambiguously assigned using 1H nuclear magnetic resonance (NMR) spectroscopy, giving the following order of elution: 13-cis, 13'-cis, all-trans, 9-cis, and 9'-cis geometrical forms. Electronic absorption spectra for these isomers were in agreement with the identification of peaks. The alpha-carotene isomers separated and identified herein had not been previously resolved in RPLC. Confirmation of the structures of geometrical alpha-carotene isomers will aid further studies on the possible physiological roles of these compounds in biological tissues.}, number={2}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={Emenhiser, C and Englert, G and Sander, LC and Ludwig, B and Schwartz, SJ}, year={1996}, month={Jan}, pages={333–343} }
 @article{emenhiser_simunovic_sander_schwartz_1996, title={Separation of geometrical carotenoid isomers in biological extracts using a polymeric C-30 column in reversed-phase liquid chromatography}, volume={44}, ISSN={["0021-8561"]}, DOI={10.1021/jf960104m}, abstractNote={Application of a polymeric C30 reversed-phase (RP) liquid chromatography (LC) column for separations of geometrical carotenoid isomers extracted from biological sources is demonstrated. The relative retention characteristics of all-trans carotenoid standards on the C30 column is also shown under isocratic conditions. Carotenoids were extracted from human serum, raw and thermally processed carrots, a Dunaliella algae-derived preparation of β-carotene, and a poultry feed supplement containing marigold carotenoids. From extracts of plant and algal origin, geometrical isomers of β-carotene (all-trans, 15-cis, 13-cis, and 9-cis), α-carotene (all-trans, 13-cis, 13‘-cis, and 9-cis), and lutein (all-trans, 13-cis, 13‘-cis, 9-cis, and 9‘-cis) were separated and tentatively identified, some of which were previously unresolved on other RPLC columns. Chromatography of serum carotenoid fractions resolved the prominent all-trans carotenoids and separated geometrical isomers of lutein, β-carotene, and lycopene (11 cis-l...}, number={12}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Emenhiser, C and Simunovic, N and Sander, LC and Schwartz, SJ}, year={1996}, month={Dec}, pages={3887–3893} }
 @article{emenhiser_sander_schwartz_1995, title={CAPABILITY OF A POLYMERIC C-30 STATIONARY-PHASE TO RESOLVE CIS-TRANS CAROTENOID ISOMERS IN REVERSED-PHASE LIQUID-CHROMATOGRAPHY}, volume={707}, ISSN={["0021-9673"]}, DOI={10.1016/0021-9673(95)00336-L}, abstractNote={A novel polymeric C30 stationary phase was tested for its ability to separate geometric isomers of six common carotenoids (lutein, zeaxanthin, β-cryptoxanthin, α-carotene, β-carotene, and lycopene) prepared by photoisomerization of all-trans standards. Resolution and tentative identification of asymmetrical carotenoid isomers yielded the 13-cis, 13′-cis, all-trans, 9-cis, and 9′-cis isomers of both lutein and α-carotene, and the 15-cis, 13-cis/13′-cis, all-trans, 9-cis, and 9′-cis isomers of β-cryptoxanthin. Among symmetrical carotenoids, the 15-cis, 13-cis, all-trans, and 9-cis isomers of both zeaxanthin and β-carotene were resolved and tentatively identified, and nineteen geometric isomers of lycopene were separated. Separations were carried out using Vydac 201TP54 and Suplex pkb-100 stationary phases for comparison; in all cases, the C30 stationary phase gave superior resolution and produced unique separations.}, number={2}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={EMENHISER, C and SANDER, LC and SCHWARTZ, SJ}, year={1995}, month={Jul}, pages={205–216} }