Nathalie Cayot

Flavor Control in Baked Cereal Products

Baked cereal products represent one of the most consumed foodstuffs in the world. Extensive scientific research has been focused on the volatile composition of these types of products. It has been shown that in spite of the great number of compounds identified, only a small number of them are responsible for the aroma. Many factors can affect the aroma composition of baked cereal products and different strategies have been proposed to improve the endogenous aroma. Furthermore, the addition of exogenous aroma compounds is extensively employed when baked cereal products with special traits are required. This article reviews the different ways in which the aroma is generated in baked cereal products and the methods that can be used to control or modify their flavor, as well as the problems related to the flavoring and the different approaches that flavor technologists have proposed to solve these problems. Some important issues and directions for future research in the flavor of baked cereal products are listed.

Effect of oxidoreduction potential on aroma biosynthesis by lactic acid bacteria in nonfat yogurt

The aim of this study was to investigate the effect of oxidoreduction potential (Eh) on the biosynthesis of aroma compounds by lactic acid bacteria in non-fat yogurt. The study was done with yogurts fermented by Lactobacillus bulgaricus and Streptococcus thermophilus. The Eh was modified by the application of different gaseous conditions (air, nitrogen, and nitrogen/hydrogen). Acetaldehyde, dimethyl sulfide, diacetyl, and pentane-2,3-dione, as the major endogenous odorant compounds of yogurt, were chosen as tracers for the biosynthesis of aroma compounds by lactic acid bacteria. Oxidative conditions favored the production of acetaldehyde, dimethyl sulfide, and diketones (diacetyl and pentane-2,3-dione). The Eh of the medium influences aroma production in yogurt by modifying the metabolic pathways of Lb. bulgaricus and Strep. thermophilus. The use of Eh as a control parameter during yogurt production could permit the control of aroma formation.

Analytical comparison and sensory representativity of SAFE, SPME, and Purge and Trap extracts of volatile compounds from pea flour.

Pisum sativum is of great economic and nutritional interest due to its protein content. Nevertheless, pea products are underused as a protein source in human food because of their strong beany flavour. Therefore, the objective of this study was to select an efficient and representative method to extract volatile molecules of pea flour. In the first step, three extraction methods were chosen: solid phase micro extraction (SPME); Purge and Trap extraction and solvent assisted flavour evaporation (SAFE). The corresponding extracts were analysed by gas chromatography coupled with mass spectrometry. In the second step, the sensory representativity of the extracts was assessed either by direct gas chromatography-olfactometry for SPME and for Purge and Trap extracts, or by sniffing for the aqueous SAFE extract. It appeared that SAFE extraction was the most suitable method because of its good extraction capacities and its high sensory representativity of the global odour of pea flour.

Influence of complexation between amylose and a flavored model sponge cake on the degree of aroma compound release.

Flavoring is used in the food industry to reinforce the aroma profile of baked cereal goods. During the processing of such products, interactions between starch and aroma compounds can occur, and this may have an impact on aroma release and perception. In the present study, 20 aroma compounds were tested to establish whether they formed complexes with amylose. The structure of the complexes was determined by wide-angle X-ray scattering (WAXS). A cocomplexation study proved that several complexing compounds could be present in the same crystalline aggregate. WAXS and differential scanning calorimetry (DSC) experiments were performed in a flavored model sponge cake at different steps of processing and showed that aroma compounds might form complexes with amylose in a sponge cake as they can do in simple system containing only amylose. Some of the aroma compounds trapped in the sponge cake were quantified, and their release behavior was followed by headspace analysis. The V-type structure could partly explain aroma retention in the product and the rate of aroma release.

Effect of oxidoreduction potential and of gas bubbling on rheological properties and microstructure of acid skim milk gels acidified with glucono-δ-lactone.

Milk oxidoreduction potential was modified using gases during the production of a model dairy product and its effect on gel setting was studied. Acidification by glucono-delta-lactone was used to examine the physicochemistry of gelation and to avoid variations due to microorganisms sensitive to oxidoreduction potential. Four conditions of oxidoreduction potential were applied to milk: milk was gassed with air, nongassed, gassed with N(2), or gassed with N(2)H(2). The rheological properties and microstructure of these gels were determined using viscoelasticimetry, measurement of whey separation, and confocal laser scanning microscopy. It appeared that a reducing environment led to less-aggregated proteins within the matrix and consequently decreased whey separation significantly. The use of gas to modify oxidoreduction potential is a possible way to improve the quality of dairy products.

Iron Fortification of Milk and Dairy Products

Blood haemoglobin level is used to define anaemia. Thresholds are given by category of age, of sex, and also of physiological status such as pregnancy. For example, the threshold is 120 g L–1 of haemoglobin in blood for a nonpregnant adult woman, 110 for a pregnant woman, 130 for a man older than 15 years, 110 for a child under 5 years… Iron deficiency constitutes the most important worldwide problem of human nutrition. In 2005, 1.62 billions of people were concerned by iron deficiency. Iron deficiency is encountered mostly in poor countries and particularly in Western Pacific, except Australia and New Zealand, in India and Pakistan, in the great majority of countries in Africa, in South America, more precisely in Brazil, Peru, and Bolivia. Iron deficiency is also spread in developed countries where 26–28 % of preschool children and nonpregnant women are deficient in iron [1]. The prevalence of iron deficiency is higher for women than for men and higher for children than for adults [2]. Iron deficiency comes from diverse origins but mainly related to the low availability of iron in food products. All types of supplementation and especially pharmaceutical forms—neutraceutical—give lower results than iron fortification of foodstuffs [3]. Iron fortification of foodstuffs remains the cheapest way to avoid iron deficiency and insure the daily intake over a long period. It is also better than tablet supplements that are known for causing digestive intolerance. Pregnant women consuming iron tablets have experienced morning sickness, nausea, and vomiting [4, 5]. These side effects explain partly the low observance of pharmaceutical correction against anaemia.

Food Protein Powder from Eisenia foetida: Dearomatization Using Food Grade Solvents and Controlled Storage Conditions

Delipidation was used to dearomatize protein powder of Eisenia foetida. The remaining volatile fraction after delipidation was studied over a period of three months. Volatile fraction dramatically increased between the first and the second month of storage. Four volatile compounds, chosen as tracers, were studied, namely: benzaldehyde, 2-pentyl furan, o-xylene, and limonene. Controlled conditions of storage are very efficient to limit volatile compound increase: 10% or less for three among the four volatile compounds chosen as tracers. The main parameter to control is temperature. To obtain a food grade protein powder, delipidation was done using ethyl acetate/ethanol instead of chloroform/methanol mixture. The remaining volatile fraction after delipidation ranged from 6% to 18%. Dearomatization was improved using an additional drying after delipidation. Solvent residues amounted to a few mg/g and conformed to EU regulations concerning solvent residues in food stuffs and food ingredients.

The Off-Flavor of Pea Flour

Pea products are underused as a protein source in human food because of their “beany” flavor. The objective of the study is to select an extraction method being the most representative for the sensory perception of the beany flavor. Solid phase microextraction (SPME) and purge and trap (P&T) extracts were analyzed by GC-MS and the sensory representation of the extracts was assessed by direct gas chromatography-olfactometry (D-GC-O). Extracted compounds were less numerous in SPME extracts than in P&T extracts. Nevertheless, the SPME method was more suitable because of its good representation of the pea suspension odor.Pea products are underused as a protein source in human food because of their “beany” flavor. The objective of the study is to select an extraction method being the most representative for the sensory perception of the beany flavor. Solid phase microextraction (SPME) and purge and trap (P&T) extracts were analyzed by GC-MS and the sensory representation of the extracts was assessed by direct gas chromatography-olfactometry (D-GC-O). Extracted compounds were less numerous in SPME extracts than in P&T extracts. Nevertheless, the SPME method was more suitable because of its good representation of the pea suspension odor.

Phase ratio variation method as an efficient way to determine the partition coefficients of various aroma compounds in mixture

Abstract The partition coefficients of aroma compounds when mixed together were determined at 30 °C in complex models of fruit preparation containing starch and pectin or carrageenan by the phase ratio variation method using a headspace autosampler. This method enabled easy determination of the partition coefficients of volatile compounds in a gas/matrix system without calibration and the results agreed well with published data obtained by other methods. Under equilibrium, an effect of polysaccharides was found only with hexanal, limonene, diacetyl and linalool. The retention was not due to interactions between aroma compounds and a polysaccharide but rather to a trapping in the complex network or to a combined effect of starch and polysaccharides.