Search

Unlabelled: The effect of Lactobacillus fermentum in co-inoculation with Saccharomyces cerevisiae UFLA CA11 on the quality of cachaça (sugar cane spirit) was evaluated. The co-inoculation was first evaluated in flask fermentation, and subsequently, yeast and bacteria were co-cultured at approximately 10(5) CFU/mL and 10(8) CFU/mL, respectively, in 4 consecutive batches. L. fermentum did not affect the growth or activity (sugar consumption and fermentation rate) of S. cerevisiae UFLA CA11 during fermentation. The physicochemical analysis revealed a higher concentration (Tukey test) of aldehydes (22.07 mg/100 mL anhydrous alcohol) in cachaça produced by co-inoculation. Analysis of volatile compounds using GC-FID demonstrated that cachaça produced by co-inoculation had higher concentrations of acetaldehyde (25.15 mg/L), ethyl acetate (30.17 mg/L), and 2,3-butanedione (170.39 μ/L), while cachaça produced by UFLA CA11 contained higher concentrations of ethyl lactate (1205.98 μ/L), propionic acid (127.97 μ/L), butyric acid (2335.57 μ/L), and 1-pentanol (469.23 μ/L). The lowest concentration of acetic acid measured by HPLC was found in cachaça obtained with UFLA CA11. The sensory analysis, performed using the Mann-Whitney test, revealed that cachaça produced by co-inoculation differed from that produced by UFLA CA11 in taste and aroma., Practical Application: This study reports on the use of a mixed culture of Saccharomyces cerevisae and Lactobacillus fermentum to produce cachaça and shows the influence of co-inoculation of yeast and bacteria on the quality of this beverage., (© 2011 Institute of Food Technologists®)

Unlabelled: The change of volatile compounds in fresh fish meat during 3- to 4-d ice storage was investigated for several fishes using an electronic nose system and a gas chromatography-mass spectrometer (GC/MS) with headspace solid-phase micro-extraction (SPME). Principal component analyses for samples using the electronic nose system revealed that the increase of some volatile compounds during storage was rapid in sardine (Sardinops melanostictus), jack mackerel (Trachurus japonicus), and chub mackerel (Scomber japonicus); moderate in yellowtail (Seriola quinqueradiata), skipjack (Katsuwonus pelamis), and young oriental bluefin tuna (Thunnus thynnus). In contrast to these fishes, the change was little in "white meat" fishes such as red seabream (Chrysophrys major), Japanese seabass (Lateolabrax japonicus), flatfish (Paralichthys olivaceus), puffer (Lagocephalus wheeleri), and bartail flathead (Platycephalus indicus). SPME-GC/MS analysis showed that some aldehydes and alcohols such as 1-heptanol, (E)-2-octenal, (E)-2-hexenal, 1-pentanol, (E,E)-2,4-heptadienal,2,4-hexadienal, 1-hexanol, 4-heptenal, and so forth increased rapidly in jack mackerel and chub mackerel, slowly in skipjack, and a little in red seabream and puffer during the storage. The increase of these compounds was considered to have an effect on the change of electronic nose response. Hexanal was a dominant compound increased from the beginning of the storage in jack mackerel. The increase of volatile compounds was little in red seabream and puffer. The increase of these aldehydes and alcohols was thought to be an appropriate marker for monitoring the freshness of "fresh" fish except for white meat fish., Practical Application: The results of this study are ready to apply for preventing fishy off-flavor of fisheries products. Lipid oxidative derivatives other than trimethylamine contributed to fresh fish flavor; therefore, to prevent lipid oxidation seemed important., (© 2011 Institute of Food Technologists®)

Headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography mass spectrometry (GC-MS) was applied for the determination of the characteristic volatile profiles of Chinese vinegars. Multivariate statistical techniques, such as principal component analysis (PCA) and cluster analysis (CA), were used to characterize the different Chinese vinegars by types, fermentation method, and production area. A total of 56 volatile compounds were identified, including 15 esters, 10 aldehydes, 5 acids, 12 alcohols, 5 ketones, 4 volatile phenols, 2 pyrazines, and 3 miscellaneous compounds. The major compounds in Chinese vinegars were furfural, acetic acid, ethyl acetate, 3-hydroxy-2-butanone, 3-methyl-1-butanol, isopentyl acetate, benzaldehyde, phenylethyl alcohol. The PCA results showed that characterizing the Chinese vinegars by HS-SPME-GC-MS was highly related to their type, fermentation method, and production area, and all these influencing factors were not independent. The CA results indicated that the fermentation method had a greater effect than vinegar type and production area. The results showed that HS-SPME-GC-MS together with chemometrics could provide practical reference for characterization of Chinese vinegars. Practical Application:  HS-SPME coupled with GC-MS was applied for the determination of the characteristic volatile profiles of Chinese vinegars. The major compounds in Chinese vinegars were furfural, acetic acid, ethyl acetate, 3-hydroxy-2-butanone, 3-methyl-1-butanol, isopentyl acetate, benzaldehyde, phenylethyl alcohol. HS-SPME-GC-MS together with chemometrics was an efficient tool for evaluating vinegar authenticity., (© 2011 Institute of Food Technologists®)

Unlabelled: The jabuticaba tree (Brazilian grape tree) is a tree native to Brazil that belongs to the Myrtaceae family. The jabuticaba fruit is used in some regions of Brazil to produce juices, jams, wine, and ice cream. In this work, the fermentation conditions (temperature and °Brix) for producing jabuticaba distillate were optimized using the response surface methodology (RSM). The optimal conditions for fermentation were found to be 20 °C and 22 °Brix. In repeated experiments to validate the model, experimental data exhibited good agreement with the predicted data. The distillate jabuticaba beverage showed a peculiar chemical composition with 20 volatile compounds that were identified and quantified. Isoamyl alcohols (2-methyl-1-butanol + 3-methyl-1-butanol) were the most abundant volatile compounds identified in jabuticaba spirit. Sensory analysis by tasters showed overall approval of jabuticaba distillate. In principal component analysis, when the beverage was evaluated by panelists under 24 y old tended to give favorable ratings of aroma and taste, as well as high overall scores. The group of panelists between the ages of 25 and 53 y old generally gave high marks for appearance in the principal component analysis., Practical Application: This study describes the study of fermentation conditions of jabuticaba pulp for production of jabuticaba spirit. Based on the results of this work, the proposed method can be an alternative for the use of the jabuticaba fruit, and may provide a new industrial outlet for this fruit., (© 2011 Institute of Food Technologists®)

Unlabelled: A powerful technique was developed for the identification and quantification of 9 volatile compounds of beer, using headspace solid phase micro-extraction (HS/SPME) and gas chromatograph coupled to a mass spectrometer and a flame ionization detector (GC/MS/FID). Optimized parameters included type of fiber, desorption time, and exposure time. Optimization was achieved with standard solutions of the target compounds. All samples were analyzed in triplicate. An exposure time of 45 min with PDMS fiber in the sample headspace was enough to reach equilibrium of the phases. A desorption time of 15 min in the gas chromatograph injector was enough for the fiber to desorb the target compounds. It was found that less polar compounds were more readily absorbed by the fiber (for example, isoamyl acetate) than more polar compounds (for example, acetaldehyde), under the extraction conditions, due to the nature of the fiber. Extraction conditions are important criteria to perform a good quantification of volatile compounds. Concentrations found in sampled beer, for the compounds of interest, ranged between 0.32 and 41.7 ppm. Results show that the reproducibility of the technique depends on the compounds. Esters have higher values (RSD mean value 5.05%) than higher alcohols (RSD mean value 2.5%) and aldehydes (RSD 3.7%). The simplicity of the validated methodology enables its use as a regular quality control procedure for beer flavor analysis., Practical Application: This study describes a technique successfully used to identify and quantify volatiles of interest in beer that can be used for quality control purposes under normal brewery production conditions. The technique uses a gas chromatograph coupled to a mass spectrometer with a flame ionization detector.

This study deals with the impact of food structure and texture on aroma release. This was done with cornstarch dispersions with constant concentrations in starch but differing in their structures. The structure parameters of the cornstarch dispersions were varied by changing the shearing conditions during the pasting process. Linalool and isoamyl acetate were chosen as reference aroma compounds. Linalool is known to form complexes with amylose while isoamyl acetate does not. The release of aroma compounds from starch dispersions under stirring was studied at 2 temperatures by discrete sampling of the headspace. Aroma release curves were modeled and the kinetic and thermodynamic parameters were extracted. The release of linalool seemed to be governed mainly by the interactions (complexation) with starch. In contrast, the interactions between starch and isoamyl acetate were feebler, and the release of this aroma compound was governed by the structure of the starch dispersion. The observed interactions were better established at 20 degrees C than at 32 degrees C.