@article{birch_fenner_watkins_boyd_2001, title={Antioxidant properties of evening primrose seed extracts}, volume={49}, ISSN={["0021-8561"]}, DOI={10.1021/jf010542f}, abstractNote={The antioxidant activity of extracts of evening primrose seeds (SE) and a commercially extracted filter cake (FC) were determined. The SE and FC were extracted with methanol/water (9:1) followed by evaporation and concentration. Extracts were tested in a bulk oil system and an oil-in-water emulsion using safflower oil as the major source of lipids. The antioxidant activity of the extracts was compared to that of a control and to that of butylated hydroxytoluene (BHT), singly, and in combination. Antioxidant activity was measured by the co-oxidation of beta-carotene, an oxidative stability instrument, conjugated dienes, and headspace analysis of hexanal. The SE extract had greater antioxidant activity than the FC extract. The SE extract was more effective in controlling the oxidation in the oil-in-water model system than in the bulk oil system. The activity of SE was concentration dependent, and at higher concentrations the SE was as effective as BHT, but it required higher concentrations because of its lack of purity. Synergism between SE and BHT was demonstrated in both model systems.}, number={9}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Birch, AE and Fenner, GP and Watkins, R and Boyd, LC}, year={2001}, month={Sep}, pages={4502–4507} }
 @article{hadden_watkins_levy_regalado_rivadeneira_breemen_schwartz_1999, title={Carotenoid composition of marigold (Tagetes erecta) flower extract used as nutritional supplement}, volume={47}, ISSN={["0021-8561"]}, DOI={10.1021/jf990096k}, abstractNote={Commercially prepared marigold flower (Tagetes erecta) extract was saponified and analyzed for carotenoid composition. HPLC analyses were performed on two normal-phase columns (beta-Cyclobond and silica) and on a C(30) reversed-phase column. The extract contained 93% utilizable pigments (detected at 450 nm), consisting of all-trans and cis isomers of zeaxanthin (5%), all-trans and cis isomers of lutein, and lutein esters (88%). All were identified by chromatographic retention, UV-visible spectra, and positive ion electrospray mass spectrometry in comparison to authentic standards. Contrary to previous findings, insignificant levels (<0.3%) of lutein oxidation products were detected in the saponified extract. This compositional determination is important for the application of marigold extract in nutritional supplements and increases its value as a poultry feed colorant because it contains more biologically useful lutein compounds than previously believed.}, number={10}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Hadden, WL and Watkins, RH and Levy, LW and Regalado, E and Rivadeneira, DM and Breemen, RB and Schwartz, SJ}, year={1999}, month={Oct}, pages={4189–4194} }
 @article{canjura_watkins_schwartz_1999, title={Color improvement and metallo-chlorophyll complexes in continuous flow aseptically processed peas}, volume={64}, ISSN={["0022-1147"]}, DOI={10.1111/j.1365-2621.1999.tb12265.x}, abstractNote={ABSTRACTFresh and frozen green peas were blanched in zinc solution (50 to 500 mg/L) and thermally processed in a particle cell reactor, which simulates a continuous flow aseptic processing system. The thermal process temperatures ranged from 121 to 145 °C at holding times from 0 to 20 min. The degradation of chlorophyll and the resulting formation of Zn‐pheophytin a and Zn‐pyropheophytin a were monitored. Quantitative analysis of the metallo‐chlorophyll complexes was performed by high‐performance liquid chromatography. Complex formation increased during heat processing and was dependent on the zinc concentration absorbed within the peas during blanching. At 130 to 145 °C, the formation of Zn‐pyropheophytin a increased and processing between 121 to 125 °C promoted the formation of Zn‐pheophytin a. Improvements in color relative to control samples suggested that the process might be applicable to two‐phase continuous aseptic processing of vegetables.}, number={6}, journal={JOURNAL OF FOOD SCIENCE}, author={Canjura, FL and Watkins, RH and Schwartz, SJ}, year={1999}, pages={987–990} }
 @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{levy_regalado_navarrete_watkins_1997, title={Bixin and norbixin in human plasma: Determination and study of the absorption of a single dose of Annatto Food Color}, volume={122}, ISSN={["0003-2654"]}, DOI={10.1039/a701304c}, abstractNote={A procedure was developed for the detection and determination of bixin and norbixin in human plasma by reversed-phase HPLC with a sensitivity limit of 5 micrograms l-1. A group of seven volunteers ingested a single dose of 1 ml of a commercial Annatto Food Color (16 mg of cis-bixin in soybean oil). The presence of bixin (cis and trans) and norbixin (cis and trans) was demonstrated in the plasma at average levels of 11.6, 10.1, 2.8 and 0 micrograms l-1 of bixin and 48, 58, 53 and 29 micrograms l-1 of norbixin after 2, 4, 6 and 8 h, respectively. Considerable individual variations were observed. Complete plasma clearance generally occurred for bixin by 8 h and for norbixin by 24 h after ingestion of cis-bixin.}, number={9}, journal={ANALYST}, author={Levy, LW and Regalado, E and Navarrete, S and Watkins, RH}, year={1997}, month={Sep}, pages={977–980} }