Synthesis of Menthol Glycinates and Their Potential as Cooling Agents.

A convenient method of synthesis has been developed for a new class of potential cooling agents, menthol glycinates. These compounds are prepared in two synthetic steps, starting from bromoacetyl bromide and (-)-menthol. The resulting brominated menthol ester readily undergoes substitution reactions with NH3 and 1° or 2° amines to provide menthol glycinates. For most of the prepared compounds, the two-step synthetic procedure requires no aqueous phase extractions.

The Important Role of Carbohydrates in the Flavor, Function, and Formulation of Oral Nutritional Supplements.

Patients who are malnourished or at-risk for malnutrition often benefit from the consumption of oral nutritional supplements (ONS). ONS supply a range of micro- and macro-nutrients, and they can be used to supplement a diet or provide total nutrition. Since ONS are specially formulated products, all ONS ingredients—including carbohydrates—are added ingredients. This may seem to be at odds with the growing public health discourse on the need to reduce “added sugars” in the diet. However, carbohydrate is an essential nutrient for human health and is a critical ingredient in ONS. Helping to educate patients on the value of “added sugars” in ONS may be useful to improve compliance with nutritional recommendations when ONS are indicated. This perspective paper reviews the important roles of “added sugars” in ONS, in terms of flavor, function, and product formulation.

Identification of compounds that contribute to trigeminal burn in aqueous ethanol solutions.

The influence of carbonyl species on the trigeminal burn of distilled spirit model systems was investigated. Quantities of the intrinsic carbonyl compounds were significantly altered in 40% ethanol solutions using two methods; (1) increasing or decreasing the product pH, to induce hemiacetal formation and acetal stabilization or induce and stabilize carbonyl species such as aldehydes, respectively and (2) utilizing a sulfonyl hydrazine polymer treatment. Samples with reduced carbonyl concentrations had significantly lower perceived trigeminal burn intensity. Sensory recombination experiments revealed that addition of carbonyl compounds increased trigeminal burn perception in model systems; confirming the direct relationship between the concentration of carbonyl compounds and trigeminal burn. The strongest potentiators of the trigeminal response were carbonyl compounds octanal, nonanal, benzaldehyde and 2-heptanone suggesting the probability that carbonyl species such as saturated aldehydes and ketones act as agonists to activate nociceptors such as TRPV1 and TRPA1 and elicit trigeminal burn.

Effect of olive mill wastewater phenol compounds on reactive carbonyl species and Maillard reaction end-products in ultrahigh-temperature-treated milk.

Thermal processing and Maillard reaction (MR) affect the nutritional and sensorial qualities of milk. In this paper an olive mill wastewater phenolic powder (OMW) was tested as a functional ingredient for inhibiting MR development in ultrahigh-temperature (UHT)-treated milk. OMW was added to milk at 0.1 and 0.05% w/v before UHT treatment, and the concentration of MR products was monitored to verify the effect of OMW phenols in controlling the MR. Results revealed that OMW is able to trap the reactive carbonyl species such as hydroxycarbonyls and dicarbonyls, which in turn led to the increase of Maillard-derived off-flavor development. The effect of OMW on the formation of Amadori products and N-ε-(carboxymethyl)-lysine (CML) showed that oxidative cleavage, C2-C6 cyclization, and the consequent reactive carbonyl species formation were also inhibited by OMW. Data indicated that OMW is a functional ingredient able to control the MR and to improve the nutritional and sensorial attributes of milk.

Identification of bitter peptides in aged cheddar cheese.

The compounds responsible for the bitter taste of aged "sharp" Cheddar cheese were characterized. Sensory-guided fractionation techniques using gel permeation chromatography and multi-dimension semi-preparative reversed-phase high-performance liquid chromatography revealed the presence of multiple bitter compounds. The compounds with the highest perceived bitterness intensity were identified by tandem mass spectrometry de novo peptide sequencing as GPVRGPFPIIV, YQEPVLGPVRGPFPI, MPFPKYPVEP, MAPKHKEMPFPKYPVEPF, and APHGKEMPFPKYPVEPF; all originated from ß-casein. Subsequent quantitative liquid chromatography-tandem mass spectrometry analysis reported that the concentrations of GPVRGPFPIIV, YQEPVLGPVRGPFPI, and MPFPKYPVEP increased during maturation by 28.7-, 3.1-, and 1.8-fold, respectively. When directly compared to young "mild" Cheddar, APHGKEMPFPKYPVEPF was reported only in the sharp Cheddar cheese, whereas the concentration of MAPKHKEMPFPKYPVEPF did not change. Further taste re-engineering sensory experiments confirmed the importance of the identified peptides to the bitterness of sharp Cheddar. The bitter intensity of the aged "sharp" Cheddar model (mild Cheddar with equivalent concentrations of the five bitter peptides in the sharp sample) was rated as not significantly different from the authentic sharp Cheddar cheese. Among the five peptides, GPVRGPFPIIV was reported to be the main contributor to the bitterness intensity of sharp Cheddar. Furthermore, a difference from control sensory test also confirmed the significance of the bitter taste to the overall perception of aged Cheddar flavor. The sharp Cheddar model was reported to be significantly more similar to aged "sharp" Cheddar in comparison to the young "mild" Cheddar cheese sample.

Control of Maillard-type off-flavor development in ultrahigh-temperature-processed bovine milk by phenolic chemistry.

The application of phenolic compounds to suppress Maillard chemistry and off-flavor development in ultrahigh-termperature (UHT)-processed milk during processing and storage was investigated. Five phenolic compounds were examined for structure-reactivity relationships (catechin, genistein, daidzein, 1,2,3-trihydroxybenzene, and 1,3,5-trihydroxybenzene). The levels of key transient Maillard reaction (MR) intermediates (reactive carbonyl species) and select off-flavor markers (methional, 2-acetyl-2-thiazoline, 2-acetyl-1-pyrroline) were quantified by LC-MS/MS and GC-MS/ToF, respectively. The addition of phenolic compounds prior to UHT processing significantly reduced the concentration of MR intermediates and related off-flavor compounds compared to a control sample (p < 0.05). All phenolic compounds demonstrated unique structure reactivity and, notably, those with a more activated A-ring for aromatic electrophilic substitution (catechin, genistein, and 1,3,5-trihydroxybenzene) showed the strongest suppression effect on the off-flavor markers and reactive carbonyl species. Sensory studies were in agreement with the analytical data. The cooked flavor intensity was rated lower for the recombination model samples of the catechin-treated UHT milk compared to the control UHT milk. Additionally, consumer acceptability studies showed catechin-treated UHT milk to have significantly higher liking scores when compared the control sample (Fisher's LSD = 0.728).

Response surface methodology as optimization strategy for reduction of reactive carbonyl species in foods by means of phenolic chemistry.

Response surface methodology (RSM) was utilized to investigate the dose-response relationships of a phenolic mixture (catechin, genistein and daidzein) as a pre-thermal processing technique to reduce reactive carbonyl species (RCSs; glyoxal, methylglyoxal and 3-deoxyglucosone) in ultra-high temperature (UHT) bovine milk. A modified derivatization technique for RCSs was developed to overcome quantitative error caused by interference from the phenolic compounds. For the statistical analysis, a Box-Behnken 3-factor (catechin, genistein and daidzein) 3-level (0.17, 0.645 and 1.12 mM) design was employed. In general, all phenolic mixtures were able to reduce RCSs in UHT milk; some compositions reported RCSs levels at or below levels reported in pasteurized milk. Predictive models with no significant lack of fit (p > 0.05), high R(2)-values (0.886-0.979) and good predictive power were developed. ANOVA analysis of the glyoxal levels indicated that only linear effects of each phenolic compound had a significant effect (p < 0.05) meaning that no significant interactions between the different phenolic compounds influenced glyoxal levels. Linear, cross product and quadratic effects of factors were reported (p < 0.05) for methylglyoxal, indicating more complicated interactions between the phenolic compounds. Both linear and quadratic effects were also reported (p < 0.05) for 3-deoxyglucosone. Overall, based on canonical analysis, catechin seemed to be the most influential factor for the reduction of RCSs in UHT milk. In summary, RSM provided a basis to understand phenolic structure-reactivity and to optimize the composition of a tertiary mixture of phenolic compounds for reduction of RCSs in UHT milk.