Journal of Food Science

ABSTRACT:  In the past, green tea has been one of the least popular nonalcoholic beverages for U.S. consumers. However, green tea has been receiving attention because of its potential health benefits. Knowing which green tea flavor attributes contribute to consumer liking will help the fast growing green tea business including green tea importers, tea shops, and beverage companies to understand which characteristics are most accepted by U.S. consumers. The objectives of this study were (1) to examine differences in acceptability of commonly available loose leaf and bagged green teas available from the major exporters to the U.S. (Japan, Korea, and China) and (2) to determine which green tea flavor characteristics are related to consumers' liking. In the study, consumers from the U.S. evaluated 6 green tea samples from China, Japan, and Korea for acceptability. A highly trained panel also evaluated the green tea samples to provide descriptive sensory attributes that might be related to acceptability. We found that U.S. consumers liked green tea samples with lower flavor intensity and lower bitterness intensity. Consumers' acceptability of green tea was negatively correlated with spinach and animalic flavor and bitterness and astringency of green teas evaluated using descriptive sensory analysis, but the correlation was only moderate. To learn what green tea flavor characteristics influence consumers' liking, future studies using more green tea samples with different flavor profiles are needed.

Aspergillus parasiticus NRRL 2999 did not produce aflatoxins on peptone‐mineral salts medium, but did accumulate blue‐fluorescent material having R_f's on thin‐layer chromatographic plates similar to aflatoxins B₁ and B₂. The blue‐fluorescent material was ultimately resolved into nine compounds. The four major compounds were tentatively identified by mass spectrometry as deoxyaspergillic acid, flavocol, deoxydehydroxymutaaspergillic acid, and 2‐hydroxy‐3,6‐di‐sec‐butylpyrazine, blue‐fluorescent pyrazines that have previously been isolated from other aspergilli. Evaluation of AOAC‐ recommended solvent systems for aflatoxin analyses indicated that diethyl ether/methanol/water (98:1:1) was the best TLC solvent system for separating aflatoxins from interferring fluorescent material. Pyrazine production was inversely related to carbohydrate content of the medium. Care should be taken in evaluating aflatoxin analyses of material with high protein and low carbohydrate levels.

Abstract:  Antioxidants are abundant compounds primarily found in fresh fruits and vegetables, and evidence for their role in the prevention of degenerative diseases is continuously emerging. However, the bioaccessibility and bioavailability of each compound differs greatly, and the most abundant antioxidants in ingested fruit are not necessarily those leading to the highest concentrations of active metabolites in target tissues. Fruit antioxidants are commonly mixed with different macromolecules such as carbohydrates, lipids, and proteins to form a food matrix. In fruits and vegetables, carbohydrates are the major compounds found, mainly in free and conjugated forms. Dietary fiber, the indigestible cell wall component of plant material, is considered to play an important role in human diet and health. Most studies on antioxidant bioavailability are focused on foods and beverages from which antioxidants are easily released. There is evidence indicating that food microstructure affects the bioaccessibility and bioavailability of several nutrients, referring mostly to antioxidants. Nevertheless, the specific role of dietary fiber in the absorption of antioxidants has not been widely discussed. In this context, the purpose of the present review is to compile and analyze evidence relating to the association between dietary fiber and antioxidants, and the physical and chemical interactions that modulate their release from the chyme in the gastrointestinal tract.

A general mathematical model in the same form with the logistic equation simulated lipid oxidation in food systems. Almost perfect agreement was found between the model and seventeen sets of data from the literature, obtained with egg yolk, restructured beef and pork nuggets, cooked pork meat, iced gutted dogfish, frozen mackerel fillets and ground raw poultry meat. A simple method was described for the evaluation of the numerical values of the model parameters. Variations of these numerical values were also associated with varying pretreatment and storage conditions.

ABSTRACT: Beef strip loins and short loins were vacuum aged for 7 or 14 d, then these cuts were dry aged for 7, 14, or 21 d. At 2, 9, and 16 d of post‐dry‐aging vacuum storage, strip steaks were analyzed for sensory, physical, and microbial differences. Controls were vacuum aged for 14 d. Dry aging for 14 and 21 d produced steaks with greater (P < 0.05) dry‐aged flavor, tenderness, and juiciness than controls or steaks dry aged for 7 d. Shear forces were lower (P < 0.05) for steaks dry aged for 21 d. Time of vacuum storage before and after dry aging had minimal effects on development of dry‐aged flavor attributes.

Abstract:  In this study, the important odor impact volatiles generated in the meat of grilled beef loin muscle were characterized. Animals were finished in 4 different diet systems: T₁, pasture (a mixture of Medicago sativa, Trifolium repens, and Festuca arundinacea); T₂, pasture supplemented with cracked corn grain (offered at 0.6% live weight, LW); T₃, pasture supplemented with cracked corn grain (offered at 1.2% LW); and T₄, concentrate (pellets with 85% corn and 12.8% sunflower, on a dry‐matter basis) plus alfalfa hay (both ad libitum). Aroma compounds were assessed by dynamic headspace‐solid phase extraction (DHS‐SPE) and gas chromatographic‐olfactometric (GC‐O) analysis. Most odorants were carbonyl compounds, some of them reaching high GC‐O scores, especially 1‐octen‐3‐one, (E)‐2‐octenal, methional, and hexanal. A specific quantitative analysis of ketones and aldehydes was conducted through their derivatization with o‐(2,3,4,5,6‐pentafluorobenzyl) hydroxylamine hydrochloride directly on the headspace trap and analyzed by GC‐MS, with the purpose of studying the effect of finishing diet systems. From the 23 carbonyl compounds quantified, 2 were especially affected by the diet system; methional was higher in the treatment based on concentrates, whereas (E,E)‐2,4‐heptadienal was higher in the treatment based only in pastures. The results are discussed considering previous published productive and quality traits.

Practical Application:  The knowledge of how production factors, such as animal feeding, can affect the flavor of meat is of significant interest toward in achieving a high‐quality and differentiated product. The development of more specific and efficient methodologies is necessary to analyze meat aroma compounds, which would be used as routine analysis, that is for product authentication. In the future, the use of this analysis would allow producing and designing specific foods according to different markets.

Glass transition of fresh red meat of bigeye tuna (Thunnnas obesus) and its filtrate occurred between —71°C and —68°C, independent of cooling rate from 1 K/min up to 50 K/min. Glass transition at low temperature appeared to occur in the liquid part. Neither dilution nor concentration of the filtrate affected the glass transition temperature (Tg) but the solute concentration of the freeze concentrated phase (Cg) was affected. Addition of salt to the filtrate caused a decrease of ∼20 K in Tg. Results suggested the possibility of qualitative improvement in quality of fish by lowering the storage temperature by 15 K below the present storage temperature (—55°C).

With a large number of isoenzyme species and substrates, peroxidases have been difficult to purify to homogeneity. By including hydrophobic chromatography in the purification scheme, a homogeneous tomato fruit peroxidase isoenzyme was obtained. The isoenzyme had a clean spectrum in the visible region and a R_z (403 nm/280 nm) value of 2.36. It showed up as a single band in disc gel electrophoresis in basic and acidic buffers, in acetate strip electrophoresis, and in both tube and slab gel SDS electrophoresis. Molecular weight estimation of this tomato peroxidase was 43,000 ± 2,000 daltons. The pH optima were at 5.5 and 7.5 with guaiacol and pyrogallol as substrate, respectively. Kinetic studies showed that pyrogallol and hydrogen peroxide could provide substrate inhibition at 5 mM concentration. Hydrophobic chromatography may be useful for purification of other food enzymes similar to tomato peroxidase.

The heat‐stable fraction of covalently immobilized peroxidase on/in porous glass beads in an environment of dodecane was studied as a bioindicator for evaluation of thermal processes under conditions of pasteurization. The verified bioindicator had a z value of 10.1°C and a Dref (at 70°C) of 22 min. At processing temperatures of 70°C and 80°C, the lethalities (F)_bio as read from the bioindicator agreed very well with the target Ft^10.0 values calculated from the time temperature data according to the general method.