On-line dynamic HS-SPME for monitoring endogenous aroma compounds released during the baking of a model cake

Unravelling caramelization and Maillard reactions in glucose and glucose + leucine model cakes: Formation and degradation kinetics of volatile markers extracted during baking

A large number of volatile compounds are formed during the baking of foods by reactions such as caramelization and Maillard reactions. Elucidating the reaction mechanisms may be useful to predict and control food quality. Ten reaction volatile markers were extracted during baking of solid model cakes implemented with known amounts of precursors (glucose with or without leucine) and then quantified by Thermal desorption-Gas chromatography-Mass spectrometry. The kinetic data showed that the level of air convection in the oven had no significant influence on the reaction rates. In contrast, increasing baking temperatures had a nonlinear accelerating impact on the generation of newly formed volatile compounds with a bell-shaped kinetic curve found for most of the markers at 200 °C. The presence of leucine triggered the activation of the Maillard and Strecker routes with a specific and very rapid formation of 3-Methylbutanal and pyrazines. A dynamic model was developed, combining evaporation flow rate and kinetic formation and consumption of reaction markers. It can be used to describe, for two furanic compounds of different volatilities, the vapor concentrations in the oven from the concentrations measured in the model cakes.

Molecular Characterization of Cooking Processes: A Metabolomics Decoding of Vaporous Emissions for Food Markers and Thermal Reaction Indicators

Thermal processing of food plays a fundamental role in everyday life. Whereas most researchers study thermal processes directly in the matrix, molecular information in the form of non- and semivolatile compounds conveyed by vaporous emissions is often neglected. We performed a metabolomics study of processing emissions from 96 different food items to define the interaction between the processed matrix and released metabolites. Untargeted profiling of vapor samples revealed matrix-dependent molecular spaces that were characterized by Fourier-transform ion cyclotron resonance-mass spectrometry and ultra-performance liquid chromatography-mass spectrometry. Thermal degradation products of peptides and amino acids can be used for the differentiation of animal-based food from plant-based food, which generally is characterized by secondary plant metabolites or carbohydrates. Further, heat-sensitive processing indicators were characterized and discussed in the background of the Maillard reaction. These reveal that processing emissions contain a dense layer of information suitable for deep insights into food composition and control of cooking processes based on processing emissions.

Applicability of pea ingredients in baked products: Links between formulation, reactivity potential and physicochemical properties

This study aimed to evaluate the applicability of purified pea ingredients (starch and protein isolate) by assessing their potential to form volatile compounds during the different steps of sponge cake development compared to pea flour and wheat flour. While pea flour was highly susceptible to lipid oxidation during batter beating, the combination of purified pea starch and pea protein yielded significantly fewer oxidation markers with known green-beany off-odors. This was due more to the inactivation of lipoxygenase during flour fractionation than to differences in batter structure. However, fractionated ingredients were highly prone to participating in the Maillard reaction and caramelization during baking, leading to a more complex mixture of pyrazines, Strecker aldehydes and furanic compounds with potential malty and roasted notes compared to cakes based on pea flour or wheat flour. These findings confirm that using purified pea fractions can create high-quality products with an attractive composition.

Aroma Clouds of Foods: A Step Forward to Unveil Food Aroma Complexity Using GC × GC

The human senses shape the life in several aspects, namely well-being, socialization, health status, and diet, among others. However, only recently, the understanding of this highly sophisticated sensory neuronal pathway has gained new advances. Also, it is known that each olfactory receptor cell expresses only one type of odorant receptor, and each receptor can detect a limited number of odorant substances. Odorant substances are typically volatile or semi-volatile in nature, exhibit low relative molecular weight, and represent a wide variety of chemical families. These molecules may be released from foods, constituting clouds surrounding them, and are responsible for their aroma properties. A single natural aroma may contain a huge number of volatile components, and some of them are present in trace amounts, which make their study especially difficult. Understanding the components of food aromas has become more important than ever with the transformation of food systems and the increased innovation in the food industry. Two-dimensional gas chromatography and time-of-flight mass spectrometry (GC × GC-ToFMS) seems to be a powerful technique for the analytical coverage of the food aromas. Thus, the main purpose of this review is to critically discuss the potential of the GC × GC-based methodologies, combined with a headspace solvent-free microextraction technique, in tandem with data processing and data analysis, as a useful tool to the analysis of the chemical aroma clouds of foods. Due to the broad and complex nature of the aroma chemistry subject, some concepts and challenges related to the characterization of volatile molecules and the perception of aromas will be presented in advance. All topics covered in this review will be elucidated, as much as possible, with examples reported in recent publications, to make the interpretation of the fascinating world of food aroma chemistry more attractive and perceptive.

A review combining emerging techniques with classical ones for the determination of biscuit quality: advantages and drawbacks

The production of biscuit and biscuit-like products has faced many challenges due to changes in consumer behavior and eating habits. Today's consumer is looking for safe products not only with fresh-like and pleasant taste, but also with long shelf life and health benefits. Therefore, the potentiality of the use of healthier fat and the incorporation of natural antioxidant in the formulation of biscuit has interested, recently, the attention of researchers. The determination of the biscuit quality could be performed by several techniques (e.g., physical, chemical, sensory, calorimetry and chromatography). These classical analyses are unfortunately destructive, expensive, polluting and above all very heavy, to implement when many samples must be prepared to be analyzed. Therefore, there is a need to find fast analytical techniques for the determination of the quality of cereal products like biscuits. Emerging techniques such as near infrared (NIR), mid infrared (MIR) and front face fluorescence spectroscopy (FFFS), coupled with chemometric tools have many potential advantages and are introduced, recently, as promising techniques for the assessment of the biscuit quality.

Elucidation of the non-volatile fingerprint in oven headspace vapor from bread roll baking by ultra-high resolution mass spectrometry

Untargeted research on vapor arising during the thermal processing of food has so far focused on volatile aroma compounds. In this study, we present an oven atmosphere sampling strategy to trap headspace aerosols along with semi- and non-volatile molecules liberated during the baking of wheat bread rolls. The collected vapor condensate was analyzed for its molecular fingerprinting using direct infusion ultra-high resolution mass spectrometry. We detected up to 4,700 molecular species in a vapor sample from bread rolls baked at 230 °C for 15 min. Beyond the global profiling of the underlying matrix, our method can follow complex reaction cascades during the baking process, such as the formation of advanced glycation end-products like maltosine through the interface of trapped vapor. Further, process parameters such as baking temperature and duration were used to model the dynamic liberation of molecules to the oven atmosphere by a response surface methodology approach.

Dynamic changes of volatile and phenolic components during the whole manufacturing process of Wuyi Rock tea (Rougui)

Wuyi Rock tea (WRT), a top-ranking oolong tea, possesses characteristic woody, floral, nutty flavor. WRT flavor is mainly formed during the manufacturing process. However, details regarding its formation process are not fully understood yet. In this study, the dynamics of volatile and phenolic components over the whole manufacturing process of WRT were investigated. During withering, despite minor changes in volatile and phenolic components, the central vacuole shrunk remarkably, which reduced the cell mechanical performance and facilitated the subsequent enzymatic fermentation. During fermentation, approximately 78% of flavan-3-ols in fresh tea leaves were oxidized and converted to a diverse mixture of highly heterogeneous oxidation products, such as theaflavins, whereas flavonols, phenolic acids, and xanthine alkaloids remained stable throughout the manufacturing process. Aldehydes, ketones, and heterocyclic compounds, imparting woody, floral, and nutty scent, were mainly formed during the roasting steps. This detailed information can expand our understanding on the formation of WRT flavor.

Egyptian kishk as a fortificant: Impact on the quality of biscuit

Introduction. Biscuit is a mass-consumption product worldwide. As biscuit contains low amount of protein, it can be fortified with protein-containing raw materials. In the present work, we fortified biscuit with kishk, an Egyptian dairy product, and evaluated changes in its physicochemical properties and volatile compounds. Study objects and methods. We analyzed biscuit from wheat flour (control sample) and biscuit form wheat flour with 10, 20, 30, 40, and 50% of kishk (experimental samples). The experiments were carried out by using standard methods. Results and discussion. The fortified biscuit samples showed higher lightness (L*) values than control. The antioxidant activity in the biscuit increased with the increasing amount of kishk. Aldehydes were the main volatile compounds in all the biscuit samples, followed by sulfur-containing compounds and alcohols. The predominant aldehyde was benzldehyde. However, kishk in amounts more than 20% affected adversely the aroma, taste and texture, as well as volatile compounds of the biscuits. Both the control and fortified with kishk biscuits contained an increased amount of total phenolic compounds. Based on sensory evaluation and volatile analysis, the most acceptable amount of kishk for fortification of biscuit was 10%. Conclusion. Fortification of biscuit with Egyptian kishk enhanced its protein, fat and fiber, as well as antioxidant activity at all levels of fortification with no significant effect on appearance and color. Further studies are needed to evaluate storage conditions and shelf life of biscuits with kishk.

Cake Perception, Texture and Aroma Profile as Affected by Wheat Flour and Cocoa Replacement with Carob Flour

Carob flour has been used in the production of a wide range of functional food formulations such as bakery goods either as a natural sweetener or food ingredient that, when roasted, exerts a chocolate/cocoa-reminiscent flavor and color. The aim of the present study was twofold; firstly to study the effect of an increasing incorporation of roasted carob flour (0-70% flour basis) on the quality and sensory attributes of a conventional cocoa cake recipe and secondly to investigate the obtained volatile fraction responsible for the aroma by means of headspace solid phase microextraction (HS-SPME) technique coupled to gas chromatography/mass spectrometry (GC/MS) while comparing it with the control, cocoa-containing cake recipe. Thirty and fifty percent carob flour incorporation rendered cakes with acceptable texture and sensory attributes, comparable to the control cake recipe containing 20% cocoa. Similarity to cocoa aroma was attributed to a great number of odor active compounds mainly belonging to aldehydes, lactones, furan/pyran derivatives, and pyrrole derivatives.

Characterising the sensory quality and volatile aroma profile of clean-label sucrose reduced sponge cakes

The sensory and aroma quality of 30% (w/w) sucrose reduced sponge cakes incorporating clean-label replacers were investigated. The sensory quality of the reformulated sponge cakes varied, with those containing apple pomace powder (APP) showing the greatest difference to the control (SC100). Volatile profiles mainly differed in relation to compounds derived from the Maillard reaction, caramelisation and lipid oxidation. Thrity six aroma active volatile compounds were identified in the SC100, APP and oligofructose (OLIGO) sponge cakes by olfactometry. Furfural 'spicy bready' contributed most to the overall aroma of all samples, with factor dilution values differing the most for heptanal 'fatty cake crust', methional 'potato damp', and 2,5-dimethylpyrazine 'cake crust, nutty'. This study provides an in-depth insight into the impact of sugar reduction reformulation on the sensory perception of sponge cakes and demonstrates how this approach can be used to improve the sensory perception of reduced sucrose sponge cakes.

Influence of Spent Coffee Ground as Fiber Source on Chemical, Rheological and Sensory Properties of Sponge Cake

BACKGROUND AND OBJECTIVE

Since spent coffee grounds (SCGs) represented the main by-product from instant coffee industry, the aim of the present study was to evaluate the use of these residues as functional food ingredient in sponge cake.

MATERIALS AND METHODS

Baked control sample (100% wheat flour) and three supplemented blends (98% wheat flour+2% SCGs, 96% wheat flour+4% SCGs and 94% wheat flour+6% SCGs) were subjected to chemical, rheological, texture, freshness, volatile, sensory and color analysis.

RESULTS

The SCGs are a promising source for dietary fiber (51.86%), protein (8.97%) and fat (13.89%) with a well-known negligible glycaemic sugar content. Supplemented sponge cake recipes with SCGs (2, 4 and 6%) reduced the degree of browning due to the lower glycaemic sugar content as well as the protein content in comparison to the control sample. A significant difference in the organoleptic properties were showed in all cake samples containing SCGs (p>0.05), which again may belong to the lower content of reduced sugars in SCGs. Volatiles extracted and identified using Solid Phase Micro-Extraction (SPME)/GC-MS have a lower content of furans, furanones and pyrazines in supplemented recipes due to the effect of lower glycemic sugar content. The higher dietary fiber content of SCGs increased volume, weight and the rheological properties of the sponge cake in addition to softened the texture.

CONCLUSION

Innovative sponge cake proved to have excellent nutritional and functional properties to be used for patients with obesity related diseases.

Characterization of key aroma-active compounds in four commercial egg flavor Sachimas with differing egg content

To characterize the aroma components of Sachima and provide insight into the influence of egg on the flavor of Sachima, the key aroma-active compounds in four commercial egg flavor Sachimas with different egg content, which named Premium, Classical, Whole egg, and Egg yolk, were identified using GC-MS-O analysis, aroma extract dilution analysis (AEDA) combined with sensory evaluation. In total, 75 volatile compounds were identified by GC-MS, including 26 compounds were revealed of having aroma activities by AEDA/GC-O. The major volatile compounds in Sachima were the aldehydes and heterocyclic compounds. The OAV further revealed the significant activity of eight key aroma-active compounds include 2-methylbutanal, 3-methylbutanal, hexanal, n-propylacetate, 2-pentylfuran, 2-ethylpyrazine, nonanal, and benzaldehyde. The OAV of 2-methylbutanal and 3-methylbutanal were much higher in Premium sample that has the most egg content, than that in other samples, whereas hexanal was the highest in Whole egg samples. The plot analyzed by PLS suggest that the Premium sample with more egg content was shown more complicated flavor than other kind of Sachima. Practical applications Sachima is a type of famous sweet Chinese traditional pastries. The flavor and texture of this kind of pastry were appreciated by all age group, especially for almost all elderly Chinese. Because Sachima is not only a suitable food that easy to chew, but a type of food which filled with childhood memory. Egg flavor of Sachima was always the most popular and classic flavor category. However, the characteristic aroma compounds of Sachima-one of the most important factor of the Sachima's quality-have been still uncovered and had not been identified yet, not to mentioned the comparison between different egg content in Sachima. What's more, GC-MS-O/AEDA analysis has been always a very effect and well-known method for aroma compounds analysis. This study trying to find the contribution of eggs to Sachima and the key aroma-active compounds of Sachima, so as to provide some useful information for practical production and flavor quality improving.

Characterization of the volatile components in green tea by IRAE-HS-SPME/GC-MS combined with multivariate analysis

In the present work, a novel infrared-assisted extraction coupled to headspace solid-phase microextraction (IRAE-HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS) was developed for rapid determination of the volatile components in green tea. The extraction parameters such as fiber type, sample amount, infrared power, extraction time, and infrared lamp distance were optimized by orthogonal experimental design. Under optimum conditions, a total of 82 volatile compounds in 21 green tea samples from different geographical origins were identified. Compared with classical water-bath heating, the proposed technique has remarkable advantages of considerably reducing the analytical time and high efficiency. In addition, an effective classification of green teas based on their volatile profiles was achieved by partial least square-discriminant analysis (PLS-DA) and hierarchical clustering analysis (HCA). Furthermore, the application of a dual criterion based on the variable importance in the projection (VIP) values of the PLS-DA models and on the category from one-way univariate analysis (ANOVA) allowed the identification of 12 potential volatile markers, which were considered to make the most important contribution to the discrimination of the samples. The results suggest that IRAE-HS-SPME/GC-MS technique combined with multivariate analysis offers a valuable tool to assess geographical traceability of different tea varieties.

How ingredients influence furan and aroma generation in sponge cake

A wide range of compounds can be formed during thermal processing of food, some of which are relevant for aroma (e.g., furfural), while others are of great health concern (e.g., furan). This paper presents the study of formulation as affecting the simultaneous generation of furan and furfural, along with other aroma quality markers, in sponge cake by means of headspace trap/GC-MS. Ingredients were screened according to their category (fat, salt, sugar, egg-based). Glucose-containing formulation resulted in the highest content of furan and furfural (12.5 ± 0.5 ng g^-1 and 9.2 ± 0.2 μg g^-1, dry basis, respectively), while their lowest amount was found in the egg-white recipe (3.1 ± 0.1 ng g^-1 for furan and 0.287 ± 0.078 µg g^-1 for furfural, dry basis). The latter also related negatively to all studied compounds. This work will be useful for developing novel strategies to deliver safe foods with appealing organoleptic attributes.

Kinetic study of furan and furfural generation during baking of cake models

This study describes the kinetics of furan and furfural generation in a cake model, for the first time. These process-induced compounds impact safety and sensory aspects of baked products. Understanding their generation with regards to process dynamics will serve food quality design. However, the complexity of real products makes this task challenging. This work provides a novel approach to understand and model chemical reactivity by implementing an inert cake model (starch, water and cellulose), specifically designed for mimicking a sponge cake structure. The addition of reaction precursors (glucose and leucine) to follow Maillard and caramelization reactions, resulted in browning and generated considerable levels of furanic compounds (up to 17.61ng/g for furan and 38.99μg/g for furfural, dry basis). Multiresponse data modeling resulted in a kinetic model which adequately describes experimental concentrations and makes it possible to estimate the degradation of precursors and the behavior of two hypothetic intermediates.

Changes in flavor volatile composition of oolong tea after panning during tea processing

Panning is a processing step used in manufacturing of some varieties of oolong tea. There is limited information available on effects of panning on oolong tea flavors. The goal of this study was to determine effects of panning on flavor volatile compositions of oolong using Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Olfactometry (GC-O). SDE and SPME techniques were applied for extraction of volatiles in panned and unpanned teas. A total of 190 volatiles were identified from SDE and SPME extractions using GC-MS and GC-O. There were no significant differences (P > 0.05) in aldehyde or terpene contents of unpanned and panned tea. However, alcohols, ketones, acids and esters contents were significantly reduced by panning. Among 12 major volatiles previously used for identification and quality assessment of oolong tea, trans nerolidol, 2- hexenal, benzaldehyde, indole, gernaiol, and benzenacetaldehyde contents were significantly decreased (P < 0.05) by panning. Panning increased (P < 0.05) contents of linalool oxide, cis jasmone, and methyl salicylate. The GC-O study also showed an increase of aroma active compounds with sweet descriptions and decrease of aroma active compounds with fruity and smoky descriptions after panning. Panning significantly changes the volatile compositions of the tea and created new aroma active compounds. Results from this study can be used in quality assessment of panned oolong tea.

Study of hydroxymethylfurfural and furfural formation in cakes during baking in different ovens, using a validated multiple-stage extraction-based analytical method

A procedure for extraction of hydroxymethylfurfural (HMF) and furfural from cakes was validated. Higher yield was achieved by multiple step extraction with water/methanol (70/30) and clarification with Carrez I and II reagents. Oven type and baking time strongly influenced HMF, moisture and volatile profile of model cakes, whereas furfural content was not significantly affected. No correlation was found between these parameters. Baking time influenced moisture and HMF formation in cakes from traditional and microwave ovens but not in steam oven cakes. Significant moisture decrease and HMF increase (3.63, 9.32, and 41.9 mg kg(-1)dw at 20, 40 and 60 min, respectively) were observed during traditional baking. Cakes baked by microwave also presented a significant increase of HMF (up to 16.84 mg kg(-1)dw at 2.5 min). Steam oven cakes possessed the highest moisture content and no significant differences in HMF and furfural. This oven is likely to form low HMF and furfural, maintaining cake moisture and aroma compounds.

Comparison of two headspace sampling techniques for the analysis of off-flavour volatiles from oat based products

Two different headspace sampling techniques were compared for analysis of aroma volatiles from freshly produced and aged plain oatcakes. Solid phase microextraction (SPME) using a Carboxen-Polydimethylsiloxane (PDMS) fibre and entrainment on Tenax TA within an adsorbent tube were used for collection of volatiles. The effects of variation in the sampling method were also considered using SPME. The data obtained using both techniques were processed by multivariate statistical analysis (PCA). Both techniques showed similar capacities to discriminate between the samples at different ages. Discrimination between fresh and rancid samples could be made on the basis of changes in the relative abundances of 14-15 of the constituents in the volatile profiles. A significant effect on the detection level of volatile compounds was observed when samples were crushed and analysed by SPME-GC-MS, in comparison to undisturbed product. The applicability and cost effectiveness of both methods were considered.

Effect of Sea Buckthorn Leaves on Inosine Monophosphate and Adenylosuccinatelyase Gene Expression in Broilers during Heat Stress

The trial was conducted to evaluate the effects of sea buckthorn leaves (SBL) on meat flavor in broilers during heat stress. A total 360 one-day-old Arbor Acre (AA) broilers (male) were randomly allotted to 4 treatments with 6 replicates pens pretreatment and 15 birds per pen. The control group was fed a basal diet, the experimental group I, II and III were fed the basal diet supplemented with 0.25%, 0.5%, 1% SBL, respectively. During the 4th week, broilers were exposed to heat stress conditions (36±2°C), after which, muscle and liver samples were collected. High performance liquid chromatography (HPLC) was performed to measure the content of inosine monophosphate (IMP); Real-Time PCR was performed to determine the expression of the ADSL gene. The results showed that the content of breast muscle IMP of group I, II and III was significantly increased 68%, 102% and 103% (p<0.01) compared with the control, respectively; the content of thigh muscle IMP of group II and III was significantly increased 56% and 58% (p<0.01), respectively. Additionally, ADSL mRNA expression in group I, II and III was increased significantly 80%, 65% and 49% (p<0.01) compared with the control, respectively. The content of IMP and expression of ADSL mRNA were increased by basal diet supplemented with SBL, therefore, the decrease of meat flavor caused by heat stress was relieved.