Computerized apparatus for measuring dynamic flavor release from liquid food matrices.

A fully computer-controlled apparatus was designed. It combines a glass reactor with a temperature-controlled hood, in which headspace volatiles are captured. Flavored liquids can be introduced into the reactor and exposed to conditions of temperature, air flow, shear rate, and saliva flow as they occur in the mouth. As the reactor is completely filled before measurements are started, creation of headspace just before sampling start prevents untimely flavor release resulting in real time data. In the first 30 s of flavor release the concentrations of the volatiles can be measured up to four times by on-line sampling of the dynamic headspace, followed by off-line trapping of the samples on corresponding Tenax traps and analysis using GC-TDS-FID. Flavor compounds from different chemical classes were dissolved in water to achieve concentrations typically present in food (micrograms to milligrams per liter). Most of the compounds showed constant release rates, and the summed quantities of each volatile of three 10 s time intervals correlated linearly with time. The entire method of measurement including sample preparation, release, sampling, trapping, thermodesorption, and GC analysis showed good sensitivity [nanograms (10 s)(-1)] and reproducibility (mean coefficient of variation = 7.2%).

Modeling dynamic flavor release from water.

A mathematical model derived from the convective mass transfer theory was developed to predict dynamic flavor release from water. A specific mass transfer correlation including a new term for volatile permeability was applied. The model was entirely based on physicochemical constants of flavor compounds and on some parameters of an apparatus used for validation. The model predicted a linear pattern of release kinetics during the first 30 s and large differences of absolute release for individual compounds. Both calculated and experimentally determined release profiles of a test mixture of flavors showed good agreement.

Caco-2 accumulation of lutein is greater from human milk than from infant formula despite similar bioaccessibility.

SCOPE: Clinical evidence suggests that the bioavailability of lutein is lower from infant formula than from human milk. The purpose of this study was to assess characteristics of human milk and lutein-fortified infant formula that may impact carotenoid delivery. METHODS AND RESULTS: Carotenoid bioaccessibility and intestinal absorption were modeled by in vitro digestion coupled with Caco-2 human intestinal cell culture. Twelve human milk samples were assessed from 1-6 months postpartum, and 10 lutein-fortified infant formula samples from three lutein sources in both ready-to-use and reconstituted powder forms. The relative bioaccessibility of lutein was not different (p > 0.05) between human milk (29 ± 2%) and infant formula (36 ± 4%). However, lutein delivery was 4.5 times greater from human milk than infant formula when including Caco-2 accumulation efficiency. Caco-2 accumulation of lutein was increasingly efficient with decreasing concentration of lutein from milk. Carotenoid bioaccessibility and Caco-2 accumulation were not affected by lactation stage, total lipid content, lutein source, or form of infant formula (powder vs. liquid). CONCLUSION: These data suggest that the bioavailability of carotenoids is greater from human milk than infant formula primarily due to intestinal absorptive processes, and that absorption of lutein is potentiated by factors from human milk especially at low lutein concentration.

Evaluation of bioequivalency and toxicological effects of three sources of arachidonic acid (ARA) in domestic piglets.

Arachidonic acid (ARA) and docosahexaenoic acid (DHA) are routinely added to infant formula to support growth and development. We evaluated the bioequivalence and safety of three ARA-rich oils for potential use in infant formula using the neonatal pig model. The primary outcome for bioequivalence was brain accretion of ARA and DHA. Days 3-22 of age, domestic pigs were fed one of three formulas, each containing ARA at ∼0.64% and DHA at ∼0.34% total fatty acids (FA). Control diet ARA was provided by ARASCO and all diets had DHA from DHASCO (Martek Biosciences Corp., Columbia, MD). The experimental diets a1 and a2 provided ARA from Refined Arachidonic acid-rich Oil (RAO; Cargill, Inc., Wuhan, China) and SUNTGA40S (Nissui, Nippon Suisan Kaisha, Ltd., Tokyo, Japan), respectively. Formula intake and growth were similar across all diets, and ARA was bioequivalent across treatments in the brain, retina, heart, liver and day 21 RBC. DHA levels in the brain, retina and heart were unaffected by diet. Liver sections, clinical chemistry, and hematological parameters were normal. We conclude that RAO and SUNTGA40S, when added to formula to supply ∼0.64% ARA are safe and nutritionally bioequivalent to ARASCO in domestic piglets.

Role of cystathionine beta-lyase in catabolism of amino acids to sulfur volatiles by genetic variants of Lactobacillus helveticus CNRZ 32.

Catabolism of sulfur-containing amino acids plays an important role in the development of cheese flavor. During ripening, cystathionine beta-lyase (CBL) is believed to contribute to the formation of volatile sulfur compounds (VSCs) such as methanethiol and dimethyl disulfide. However, the role of CBL in the generation of VSCs from the catabolism of specific sulfur-containing amino acids is not well characterized. The objective of this study was to investigate the role of CBL in VSC formation by Lactobacillus helveticus CNRZ 32 using genetic variants of L. helveticus CNRZ 32 including the CBL-null mutant, complementation of the CBL-null mutant, and the CBL overexpression mutant. The formation of VSCs from methionine, cystathionine, and cysteine was determined in a model system using gas chromatography-mass spectrometry with solid-phase microextraction. With methionine as a substrate, CBL overexpression resulted in higher VSC production than that of wild-type L. helveticus CNRZ 32 or the CBL-null mutant. However, there were no differences in VSC production between the wild type and the CBL-null mutant. With cystathionine, methanethiol production was detected from the CBL overexpression variant and complementation of the CBL-null mutant, implying that CBL may be involved in the conversion of cystathionine to methanethiol. With cysteine, no differences in VSC formation were observed between the wild type and genetic variants, indicating that CBL does not contribute to the conversion of cysteine.