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The role of conching in chocolate flavor development: A review

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Comprehensive Reviews in Food Science and Food Safety
Authors:
Pedro Pio Campregher Augusto at State University of Campinas (UNICAMP)
Pedro Pio Campregher Augusto
Helena M. A. Bolini
Helena M. A. Bolini
Helena M. A. Bolini
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Abstract and Figures

Chocolate is an indulgent product whose consumption is mostly motivated by its alluring sensory properties. Among them, flavor stands as the key driver for consumer preference and purchase intention. Flavor is a complex multimodal perception whose discrimination depends mostly on the retronasal aromas associated with the presence of odor‐active compounds in the matrix. The development of chocolate flavor relies on several factors, ranging from intrinsic properties of raw materials to formulation and processing conditions. As the last step of liquid chocolate manufacture, conching develops proper fluidity/texture and finetunes flavor, by means of intensive mixing and continuous heating of chocolate mass for several hours. Time and temperature are the main parameters determining the extent of conching effects upon flavor, despite factors such as ventilation, energy input onto chocolate mass, and configuration of conching machine being also relevant to some of the physicochemical mechanisms involved in flavor modification. Overall, conching impacts chocolate flavor by either changing the concentration of key odor‐active compounds or modifying their distribution throughout the matrix, affecting their binding to other components and, ultimately, their rate of release during ingestion. The present review aims to gather evidence on the physicochemical transformations promoted by conching responsible for flavor enhancement and overall sensory quality of chocolates.
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The role of conching in chocolate avor development: A review
Pedro Pio C. Augusto, Helena M. A. Bolini
Comprehensive Reviews in Food Science and Food Safety, May 2022, Wiley
DOI: 10.1111/1541-4337.12975
How conching aects chocolate avor
Photo by Hayeld L on Unsplash
What is it about?
Conching is the last stage of liquid chocolate manufacturing, in which chocolate mass
is heated and kneaded for several hours in specialized machines, called conches. It is
essential to develop avor and texture in the nal product. We have comprehensively
reviewed the key physicochemical mechanisms taking place during conching that are
responsible for changing and improving the avor of chocolates.
Why is it important?
Setting conching parameters is often done based on trial-and-error or
manufacturer's expertise. Therefore, a more rational approach to the process could
be helpful to professionals in the chocolate industry to achieve better and more
consistent avor proles in their products. We have examined not only the inuence
that dierent conching conditions have upon avor, but also their correlation with
inherent properties of chocolate, such as formulation and the quality of raw
materials.
Perspectives
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PA
Pedro Pio Campregher Augusto
Universidade Estadual de Campinas
Throughout my career in the confectionery industry, I have perceived some mystery
surrounding the conching process and its eects upon chocolate avor. This has
motivated me to study this subject in my PhD degree and to write this review along
with my academic supervisor, Dr. Bolini. Writing about avor was a challenge, as
lexicons are rarely homogenous among studies and allude to very complex sets of
sensations. However, I overcame that by gathering and comparing data from both
sensory and instrumental studies, which became a dierential aspect of this review.
The following have contributed to this page: Pedro Pio Campregher Augusto
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... Time is a critical process parameter of conching and can be a limitation in productivity (Toker et al., 2019). It depends on factors such as conche's design and operation, chocolate's recipe, raw materials' composition, and the quality intended for the finished product (Augusto and Bolini, 2022). The first models of conching machines often required up to 96 h to achieve the desirable sensory properties of chocolates, whereas cycles in modern conches usually last between 6 and 12 h (Beckett et al., 2017). ...
... In fact, samples attained nearly identical sensory profiles, as presented in the radar chart in Figure 2, suggesting that conching milk chocolates for longer than 6 h in the present processing concept would be redundant and unnecessary to further develop or modify their sensory properties. It is generally believed that the flavor development occurring during conching is less important for milk chocolates than it is for dark chocolates, due to the latter's higher content of cocoa solids and the absence of milk solids, which would otherwise mask cocoa's bitterness, acidity, and astringency (Augusto and Bolini, 2022). Some authors suggest that, in the case that only high-quality raw materials are used, conching is not required to enhance the flavor and aroma of milk chocolates and, instead, the development of rheologic properties and mouthfeel in the final product is its main contribution to quality (Bolenz et al., 2003(Bolenz et al., , 2007. ...
The influence of conching time on the sensory profile and consumer acceptance of milk chocolates enriched with freeze-dried blueberry (Vaccinium spp.)
Article
  • Jun 2023
  • FOOD SCI TECHNOL INT
Conching is a processing stage of industrial chocolate manufacture that is essential to the development of the sensory and rheological properties of the finished product. It promotes the physicochemical changes leading to flavor, aroma, and flowability refinement by continuously heating, aerating, shearing, and homogenizing chocolate mass during an extended time length. Conching duration is a key processing parameter that depends on the type of chocolate, the quality of primary ingredients, the conche's configuration, and the desired sensory outcome in the chocolate. Shorter cycles are often beneficial to manufacturers, due to increased productivity and reduced energy consumption, but they may be insufficient to fully develop chocolate's desired sensory properties. The present study aimed to shed light on the trade-off between product quality and process efficiency by assessing if varying conching durations were associated with statistically significant differences in the sensory profile and consumer acceptance of milk chocolates with freeze-dried blueberry. Samples were produced under an alternative method of conching prior to ball mill refining, with times investigated being 6, 12, 24, 36, 48, and 72 h, and were subsequently submitted to Quantitative Descriptive Analysis and consumer acceptance test. No statistically significant differences in either sensory profiles or consumer acceptance ratings of samples were observed, with the exception of hedonic values for aroma, indicating that a 6-h conching cycle was already enough to develop the sensory properties of the milk chocolate with freeze-dried blueberry. The feasibility of shorter conching times suggests a potential for energy saving and increased productivity in the production of milk chocolates following the conching prior to ball mill refining concept.
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... Aroma-relevant changes during conching are supposed to underlie evaporation, re-distribution, and formation (Counet et al., 2002;Ziegleder et al., 2003;Owusu et al., 2012;Albak and Tekin, 2016). Particularly undesired aroma compounds, such as excess acetic acid and other short-chain acids that could negatively affect the chocolate flavor, are removed by evaporation (Owusu et al., 2012;Engeseth and Ac Pangan, 2018;Augusto and Bolini, 2022). However, desired compounds are removed during conching as well (Counet et al., 2002;Owusu et al., 2013;Ziegleder, 2017). ...
Conching of dark chocolate – Processing impacts on aroma-active volatiles and viscosity of plastic masses
Article
  • Oct 2024
The conching process plays a key role in determining the sensory and rheological properties of dark chocolate. To further understand this process, changes in the chocolate mass during plastic conching were investigated on a time-resolved basis with varying conching temperature, shear direction, and with or without the presence of residue from previous trials (pre-charge) on the conche vessel wall. Six selected odorants (acetic acid, benzaldehyde, linalool, 2,3,5,6-tetramethylpyrazine, 2-phenylethanol, 2-phenylethyl acetate) were quantified in fat and particle phases of chocolate masses. Particularly at elevated conching temperature, the odorant concentrations were found to decrease (up to 78.0% in the fat phase). The highest concentrations of desired odorants were determined mostly after conching without pre-charge. During conching, odorants were observed to accumulate increasingly in the fat phase (up to 91.7%) with decreasing odorant polarity. Similarly, it was found that conching temperature and the absence of pre-charge had the highest impact on the rheological properties of the chocolate mass, resulting in lowest and highest complex viscosity, respectively. In conclusion, some positive outcomes of conching, namely the retention of desired odorants and the reduction of viscosity, were inversely related at elevated temperature or in the absence of pre-charge, necessitating compromises to achieve optimal flow properties and flavor. Our results contribute to a deeper understanding of the influence of conching on the quality of dark chocolate by providing insights into the complexity of aroma migration and rheological changes during conching.
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... Additionally, Febrianto et al. (2022) and Muñoz et al. (2020) reviewed the formation of flavor during processing. Furthermore, Augusto and Bolini (2022) focused on the conching process, Diaz- Munoz and De Vuyst (2021) and Mota-Gutierrez et al. (2019) explored the impact of fermentation, and Rojas et al. (2022) provided insights into the role of roasting in flavor development. ...
Sensory attributes of fine flavor cocoa beans and chocolate: A systematic literature review
Article
Full-text available
Fine flavor cocoa (FFC) is known for its unique flavor and aroma characteristics, which vary by region. However, a comprehensive overview of the common sensory attributes used to describe FFC beans and chocolate is lacking. Therefore, a systematic review was conducted to analyze existing literature and identify the most commonly used sensory attributes to describe FFC beans and chocolate. A systematic search of the Web of Science and Scopus databases was conducted in May 2023, and Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guidelines were followed to ensure transparency and reproducibility. This review summarizes the origins of cocoa and explores their unique flavor profiles, encompassing caramel, fruity, floral, malty, nutty, and spicy notes. Although some origins may exhibit similar unique flavors, they are often described using more specific terms. Another main finding is that although differences in sensory attributes are anticipated at each production stage, discrepancies also arise between liquor and chocolate. Interestingly, fine chocolate as the final product does not consistently retain the distinctive flavors found in the liquor. These findings emphasize the need for precise descriptors in sensory evaluation to capture flavor profiles of each origin. As such, the exploration of attributes from bean to bar holds the potential to empower FFC farmers and chocolate producers to effectively maintain quality control.
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... Typically, conching for dark chocolate occurs at temperatures between 70 and 80 • C (Wollgast & Anklam, 2000), while lower temperatures, approximately 50-60 • C, are favored for milk chocolate (Urbańska et al., 2021). Traditional conching processes primarily aim to control particle dimension, enhance mouthfeel, and regulate moisture content (MC), rather than to eliminate bacteria (Augusto & Bolini, 2022). To ensure production of safe chocolate products, it is imperative to assess if the current conching operations are able to achieve adequate Salmonella reduction and, more importantly, if there is a need for modifications to the conching conditions or additional thermal processing. ...
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... More than 55% of respondents revealed that emotional satisfaction (indulgence) is the main reason for consuming chocolate. It may be due to cravings [12], a need for elevated mood and energy levels or because it is seen as pleasurable, relaxant, aphrodisiac and may act as an antidepressant [46]. A similar study found that most participants consumed chocolate at least once a week, ate chocolate for satisfaction (indulgence) and flavour was the main reason for purchases [27]. ...
Development of Emotion Lexicons to Describe Sugar-Free Chocolate According to Consumers’ PROP Taster Status
Article
Full-text available
  • Dec 2023
Taste sensitivity can have a significant impact on consumers’ food choices. Consumers’ taster status and emotions can be guided by sensory information of sugared products. This paper aimed to develop emotional lexicons for sugar-free chocolates based on consumers’ taster status applying the check-all-that-apply (CATA) methodology. South African respondents’ (n = 153) bitter perception was evaluated with n-propylthiouracil (PROP) paper strips. Respondents received one sugar-free dark chocolate and one sugar-free milk chocolate and completed an electronic questionnaire. Respondents mainly purchased chocolate for its flavour, and enjoyed the taste of the sugar-free dark chocolate more than sugar-free milk chocolate. The non-tasters (>50%) chose positive emotions for sugar-free milk chocolate, while the medium tasters, selected more positive emotions for dark chocolate. The supertasters selected the most negative emotions for the sugar-free dark chocolate. Practical significant associations were found between the non-tasters and the emotion guilty, as well as between the supertasters and the emotions, discontented and disgust. Each taster status requires the development of a distinctive lexicon to be emotionally satisfied by sugar-free products.
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... (1) Mixing cocoa products with sugar, milk, or other ingredients according to chocolate type and formulation and the ensuing processing steps for obtaining the solid chocolate bar; (2) After mixing, the liquid chocolate paste is refined to further reduce particle sizes, ensuring flowability and adequate sensory properties. During refining, temperatures can reach 60 • C because of viscous dissipation, but cooling is applied to reduce the temperatures so that adequate viscosity is maintained throughout the process [14]; (3) The chocolate is then conched, which is a stirring operation at temperatures above 50 • C for a few hours to remove undesirable volatile compounds to reduce acidity and further develop flavor as well as viscosity and texture [41]. Conching is crucial in chocolate processing for the development of sensory and quality characteristics [42]; (4) The chocolate undergoes tempering to promote adequate fat crystallization in cocoa butter's most thermodynamically stable form [16,39]. Fat crystallization and its control are critical in defining chocolate quality [43]. ...
Can Chocolate Be Classified as an Ultra-Processed Food? A Short Review on Processing and Health Aspects to Help Answer This Question
Article
Full-text available
  • Aug 2023
Chocolate is a confectionery product whose consumption has increased, particularly dark chocolate. Chocolate is produced with varying amounts of cocoa liquor (CL), cocoa butter (CB) and cocoa powder (CP). The main chocolate types are dark, milk and white. Processing steps for chocolate production are described, and nutritional compositions examined for benefits and risks to health. Chocolate processing comprises steps at farm level, initial industrial processing for production of CL, CB and CP (common for all chocolate types) and mixing with other ingredients (like milk and sugar differing according to chocolate type) for industrial chocolate processing. All chocolate types present similar processing levels, and none involve chemical processing. Nutritional profiles of chocolate products differ according to composition, e.g., dark chocolate contains more CL, and so a higher antioxidant capacity. Chocolate is an energy-dense food rich in bioactive compounds (polyphenols, alkaloids, amino acids). Studies have demonstrated benefits of moderate consumption in reducing cardiovascular risk and oxidative and inflammatory burden, improving cognitive functions, maintaining diversity in gut microbiota, among others. In our view, chocolate should not be classified as an ultra-processed food because of simple processing steps, limited ingredients, and being an important part of a healthy diet when consumed in moderation.
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... Another important feature highlighted by Alvarez et al. [48] is the observation of an inverse or negative relationship between herbal and nutty flavor. This means that the higher the herbal attribute, the lower the nutty flavor, which could be explained by the relationship that exists between the herbal and the bad or low fermentation of the grain, since it is characterized by a green or fresh grass flavor, contrasting with what could be the development of the nutty flavor [90,91]. ...
Spatial Distribution of Cocoa Quality: Relationship between Physicochemical, Functional and Sensory Attributes of Clones from Southern Colombia
Article
Full-text available
  • Dec 2022
Citation: Ramón, V.; Hernández, H.E.; Polania, P.; Suárez, J.C. Spatial Distribution of Cocoa Quality: Relationship between Physicochemical, Functional and Sensory Attributes of Clones from Southern Colombia. Agronomy 2023, 13, 15. https://doi. Abstract: Cocoa quality is affected by genetic variability and conditions in the region of origin that impact the physicochemical, functional and sensory characteristics of the cocoa bean. For the purpose of this study, the spatial distribution was analyzed using a cocoa quality indicator that related physicochemical, functional variables (phenolic and antioxidant content) and sensory attributes (organoleptic qualities and sensory notes) of cocoa samples from different cocoa clones in the municipalities of Mesetas and Vista Hermosa in the department of Meta, Colombia. In 83 sampling plots distributed in 22 farms with agroforestry cocoa arrangements, 50 pods of the main clone were selected in each plot. Subsequently, the cocoa bean samples were subjected to fermentation and drying processes using a uniform process, then each of the samples was subjected to physicochemical, functional and sensory properties. A medium quality level was found in the cocoa beans that depended on genetic variability, whose properties ranged between protein levels of 10.312%, sugars of 2.7-3.7 • Brix, and fat contents of 51.5-52.2%, with 178.4-235.2 mg GAE g −1 in total phenol content and 1208.1-3464.1 µmol AAE g −1 in antioxidant capacity. Clones TSH-565 and FEAR-5 showed respectively higher and lower grain quality. Within the sensory profile, complementary aromatic notes such as floral, fruity, nutty, malty, with high correlations between acidity and fresh fruit, astringency and cocoa, and astringency and bitterness, were found. At the clone level, ICS-95 and TSH-565 presented the best sensory attributes (floral, sweet, acidity, fresh fruit). According to the physicochemical, functional and sensory variables of the cocoa beans, it was found that only 13% of the samples presented values higher than 0.8 in the cocoa quality index, with notes of banana, melon, peach, plum, and fresh fruit related to clones such as TSH-565 and ICS-95, whose notes are considered high-quality; these cocoa plantations are located in the Palestina village in the municipality of Vistahermosa and in the Las Mercedes village in the municipality of Mesetas.
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Impact of processing on important cocoa off-flavour compounds
Article
Full-text available
  • Jan 2022
  • EUR FOOD RES TECHNOL
The compounds responsible for smoky and mouldy–musty off-flavours in fermented cocoa have recently been elucidated; however, their behaviour during further processing into chocolate was still unclear. The compounds 2-methoxyphenol, 3-methylphenol, 4-methylphenol, 3-ethylphenol, 4-ethylphenol, and 3-propylphenol known to contribute to smoky off-flavours showed a tendency towards a minor increase during roasting and processing into cocoa liquor. This increase amounted to 1.4-fold at the most, however, was clearly compensated by losses of 30–63% during further processing into chocolate mass and conching. Among the off-flavour compounds identified in mouldy–musty smelling cocoa, faecal, mothball-like 3-methyl-1H-indole showed a clear decrease during roasting and processing into cocoa liquor, at least at rather high roasting temperatures, and a further decrease during processing into chocolate mass and conching. In contrast, faecal, mothball-like 1H-indole substantially increased during roasting and processing into cocoa liquor, namely from concentrations below its odour threshold value to concentrations up to 8 times beyond its odour threshold value. During processing into chocolate mass and conching, 1H-indole remained virtually unchanged. The data suggested that the monitoring of off-flavour compounds at the incoming goods inspection in the chocolate industry should not be limited to the fermented beans as such but additionally include the analysis of a bean sample after test roasting to correctly assess the off-flavour potential of 3-methyl-1H-indole and 1H-indole.
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Consumption practices & COVID IJCS online May 21
Article
Full-text available
  • May 2021
  • Int J Consum Stud
This research draws on protection motivation theory, temporal construal theory and self-determination theory to understand consumption practices during a pandemic crisis by looking at the narratives of British consumers during the COVID-19 crisis. A two-stage design is adopted; the first stage adopts an exploratory strategy to identify consumption-related themes using netnography, while the second stage explores these themes further to gain a deeper insight through 13 semi-structured interviews. Three themes emerge relating to different aspects of consumption practices. These themes are found to link to the self-control research area and include consumers’ self-control changing their shopping behaviour, having less self-control over unhealthy snack consumption and having less self-control concerning alcohol. These lead to changes in other consumption practices, including store format and type of shopping. Different initiatives are discussed to help retailers retain their new lockdown customers, to help manufacturers provide healthier options and to help weight management businesses and the National Health Service reduce unhealthy consumption habits.
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Comparison of the Effects of Conching Parameters on the Contents of Three Dominant Flavan3-ols, Rheological Properties and Sensory Quality in Chocolate Milk Mass Based on Liquor from Unroasted Cocoa Beans
Article
Full-text available
The content of polyphenols in chocolate depends on many factors related to the properties of raw material and manufacturing parameters. The trend toward developing chocolates made from unroasted cocoa beans encourages research in this area. In addition, modern customers attach great importance to how the food they consume benefits their bodies. One such benefit that consumers value is the preservation of natural antioxidant compounds in food products (e.g., polyphenols). Therefore, in our study we attempted to determine the relationship between variable parameters at the conching stage (i.e., temperature and time of) and the content of dominant polyphenols (i.e.,catechins, epicatechins, and procyanidin B2) in chocolate milk mass (CMM) obtained from unroasted cocoa beans. Increasing the conching temperature from 50 to 60 °C decreased the content of three basic flavan-3-ols. The highest number of these compounds was determined when the process was carried out at 50 °C. However, the time that caused the least degradation of these compounds differed. For catechin, it was 2 h; for epicatechin it was 1 h; and for procyanidin it was 3 h. The influence of both the temperature and conching time on the rheological properties of chocolate milk mass was demonstrated. At 50 °C, the viscosity and the yield stress of the conched mass showed its highest value.
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Changes in Food Consumption During the COVID-19 Pandemic: Analysis of Consumer Survey Data From the First Lockdown Period in Denmark, Germany, and Slovenia
Article
Full-text available
  • Mar 2021
This paper focuses on changes in food consumption that occurred during the COVID-19 pandemic. Its objective is to map changes at individual consumer level and identify the influence of different factors related to the COVID-19 pandemic on changes in individual food consumption. We conducted a cross-sectional online survey among 2,680 residents of Denmark (DK), Germany (DE), and Slovenia (SI) using quota sampling for gender, age and regional distribution. Data on consumption frequencies before and during the pandemic were collected with a food frequency questionnaire in the spring of 2020 (during the first lockdown period) for important types of fresh food and non-perishable food. Our results showed that, depending on the type of food, 15-42% of study participants changed their consumption frequency during the pandemic, compared to before. In all the study countries, the food categories with the highest rates of change were frozen food, canned food, and cake and biscuits; among the food categories with lower rates of change were bread, alcoholic drinks, and dairy products. People across all three countries shopped less frequently during lockdown and there was an overall reduction in the consumption of fresh foods, but an increase in the consumption of food with a longer shelf life in Denmark and Germany. Interestingly though, we observed diverging trends in all food categories analyzed, with some people decreasing and others increasing their consumption frequencies, demonstrating that the pandemic had different impacts on people's lifestyles and food consumption patterns. Using the method of multinomial regression analysis, we identified factors significantly (p < 0.01, p < 0.05, p < 0.1) related to increases and decrease in individuals' consumption frequencies in different food categories. The factors include restrictions put in place in response to the pandemic (i.e., closure of physical workplaces, canteens, cafés and restaurants, schools, and childcare institutions), changes in households' grocery shopping frequency, individuals' perceived risk of COVID-19, income losses due to the Janssen et al. Changes Food Consumption COVID-19 pandemic, and socio-demographic factors. Interesting differences between the countries were detected, allowing insights into the different food cultures. Conclusions include implications for policy-makers and actors in the food supply chain on the issues of healthy diets, food system resilience, and behavior change.
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Effect of cocoa roasting time on volatile composition of dark chocolates from different origins determined by HS-SPME/GC-MS
Article
Full-text available
  • Jan 2021
In this study the volatile composition of six samples of dark chocolates varying in the cocoa roasting time (30.5, 34.5 and 38.5 min) and geographical origin (Ecuador and Ghana) was characterized by headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS). One hundred and twenty-one different compounds were identified using a carboxen/polydimethylsiloxane (CAR-PDMS) fiber comprising acids, alcohols, aldehydes, alkanes, esters, furans, ketones, nitrogen compounds, pyran derivatives, pyrazines, pyrroles and thiazoles. The effect of roasting time on the volatile composition of chocolates depended on their geographical origin. Principal component analysis (PCA) was applied to volatile composition of the six dark chocolate samples. Eight different groups of compounds were established according to the position of the aroma compounds on the PC plot and accordingly to variation among samples. Therefore, volatile compounds that appeared or disappeared during roasting of cocoa from each origin or both origins were identified.
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Oral processing preference affects flavor perception in dark chocolate with added ingredients
Article
Full-text available
Chocolate has specific rheological behavior during oral processing that delivers its distinct sensory characteristics. When incorporating functional or flavoring ingredients into chocolate, these properties must be maintained to meet consumer expectation. Water‐soluble and fat‐soluble ingredients have a potential effect on the properties of chocolate; therefore, successfully adding functional supplements in this medium can have challenges. This study investigated the effect of functional or flavoring ingredients on chocolate microstructure, mouthfeel (texture), and flavor release, during oral processing. Participants were classified by their oral processing “pattern”: a chewing preference (CP), a sucking preference (SP), and a mixed group who had a preference for both chewing and sucking (MP). Chocolate samples (72% dark chocolate) were prepared with different flavor ingredients (water‐soluble: ginger powder and fat‐soluble: menthol). Instrumental testing of chocolate viscosity and hardness showed no significant differences in chocolate with low concentrations of added ingredients (0.5% ginger and 0.1% mint), while chocolate with higher concentration (2.5% ginger and 0.5% mint) showed a significant difference compared to standard chocolate. Modified Qualitative Descriptive Analysis (MQDA) tests showed no significant differences in sensory perception of texture between the formulations, or the oral processing behavior groups. There was an impact on flavor perception both from composition and from oral processing behavior. The CP group rated the chocolate with the lowest flavoring concentration as also having the lowest cocoa flavor intensity. Moreover, the MP and SP groups showed a similar perception of cocoa flavor intensity.
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On-line estimation for predicting the “Conching Degree” (CD) and the viscosity of chocolate
Article
  • Sep 2021
  • J FOOD ENG
The conching process is one of the main stages of chocolate manufacture involving the development of sensory attributes and the product rheological properties. At the current operation of the conching process, the on-line estimation of quality properties that define an optimal development of the chocolate is not possible. In that sense, the on-line estimation of the “Conching Degree” (CD) as a flavor quality indicator and the chocolate viscosity as a textural quality attribute are fundamental tasks for guaranteeing process monitoring and real-time decision making. To this aim, this paper proposes a Moving Horizon Estimator (MHE) for the on-line estimation, instead of measurement, of the CD and the viscosity of chocolate. In this formulation, only available physical measurements of process variables easy to obtain are required, avoiding time-consuming and extensive conventional laboratory methods to quantify these chocolate’s quality indicators. The estimator is designed as an optimization problem over a moving horizon, constrained to a Phenomenological Based Semi-Physical Model (PBSM) describing the conching process main phenomena. The performance of the proposed estimator is evaluated by simulation with data from a real plant. Finally, the proposed optimization-based estimation structure allows estimating the CD and the viscosity of chocolate with estimation indices errors lower than 6% considering only two available measurements in the process.
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Molecular Background of a Moldy-Musty Off-Flavor in Cocoa
Article
  • Apr 2021
  • J AGR FOOD CHEM
The parallel application of aroma extract dilution analysis to the volatiles isolated from a sample of fermented cocoa seeds with a pronounced moldy-musty off-flavor and to the volatiles isolated from a flawless reference sample revealed (-)-geosmin, 4-methoxy-2,5-dimethylfuran-3(2H)-one, 1H-indole, and 3-methyl-1H-indole as potential off-flavor compounds on the basis of their odor quality and higher flavor dilution factors in off-flavor cocoa than in the reference sample. Quantitation of the four compounds in nine off-flavor cocoa samples and calculation of odor activity values (ratio of the concentrations to the odor threshold values) suggested the crucial roles of (-)-geosmin and 3-methyl-1H-indole for the off-flavor. In the chocolate industry, their quantitation can be used to objectively assess the off-flavor at the level of incoming goods inspection. Because both compounds are inhomogeneously distributed between the testa and the embryo, separate quantitation in the two parts of the seeds is required.
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Effects of packaging color on expected flavor, texture and liking of chocolate in Brazil and France
Article
  • Mar 2021
Recent research has shown that the colors of plateware, glassware, cups, packaging, and even the room and its lighting are able to influence consumers’ preferences, expectations and perceptions of taste, flavor and texture of food and beverages. This study contributes to the subject by investigating how packaging colors affected the expectations of sweetness, bitterness, fruitiness, melting, and liking for chocolates in Brazil and France. Two groups of 210 consumers (N = 420) from each country evaluated samples of milk and dark chocolate packaged in seven colors: black, blue, brown, green, red, pink and yellow. Analyses of variance (ANOVA) indicated that there were multiple significant effects of packaging color on consumers’ expectations. Multiple factor analysis (MFA) showed that expected sweetness, fruitiness and liking were correlated to each other and inversely correlated to expected bitterness. While milk and dark chocolate were expected the least sweet and the most bitter when in black packaging, they were expected the sweetest and the least bitter when in yellow or pink packaging. Interestingly, the same black packaging made the milk chocolate the best rated and the dark chocolate the worst rated on expected liking, showing that a color may have inverse effects on expected liking depending on the type of chocolate. Although French consumers eat more chocolate and with higher cocoa content than Brazilians, the effects of packaging color were not significantly different between cultures.
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Characterization of the Key Aroma Compounds in a Commercial Milk Chocolate by Application of the Sensomics Approach
Article
  • Oct 2020
Compared to dark chocolate, which is mainly produced from roasted cocoa and sucrose, milk chocolates contain different dairy products, such as milk powder, butter fat, or dairy cream. This difference in recipe renders a typical aroma attributed to this type of chocolate, often described as milky or creamy. To get an idea of the odorants responsible for this odor note, an aroma extract dilution analysis was applied on a distillate obtained by extraction and SAFE distillation of a commercial milk chocolate evaluated with an intense "milky, creamy" attribute. The identification experiments in combination with the flavor dilution (FD) factors revealed 48 odor-active compounds, among which phenylacetic acid (honey-like) and vanillin (vanilla-like) showed the highest FD factors followed by 2-methoxyphenol (smoky) and nonanoic acid (musty, pungent). The quantitation of 40 odorants by stable isotope dilution assays (SIDA) and a subsequent calculation of odor activity values (OAV; ratio of concentration to odor threshold) revealed dimethyl trisulfide (cabbage-like) and butanoic acid (sweaty) with the highest OAVs (>170), followed by 3-methylbutanoic acid (sweaty), acetic acid (vinegar-like), and phenylacetic acid. An aroma recombinate prepared with 39 reference odorants in the same concentrations as those determined for the compounds in the milk chocolate showed a good similarity with the overall aroma profile of the milk chocolate. A comparison of the results with the recent literature data on dark chocolates also evaluated by the Sensomics approach suggested that, in particular, methanethiol and a series of lactones may contribute to the milky, creamy odor note because these were reported with much lower odor activities in the dark chocolates.
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