SENSORY CHARACTERISTICS OF COMBINATIONS OF CHEMICALS POTENTIALLY ASSOCIATED WITH BEANY AROMA IN FOODS

Comparison of volatile compound profiles derived from various livestock protein alternatives including edible-insect, and plant-based proteins

In this study, the distinctive chemical fingerprints that contribute to the flavor characteristics of various protein materials, such as insects, plant-based protein, and livestock, were investigated. In edible-insects (Tenebrio molitor and Protaetia brevitarsis), aldehydes and cyclic volatile compounds were the predominant volatile components and had distinct flavor characteristics such as cheesy, sharp, green, floral, and sweet. In contrast, the relatively high levels of pyrazines and furans in plant-based protein materials, such as textured vegetable and pea protein. They included unique flavor properties characterized by sweet, fatty, grassy, creamy, and roasted. The primary volatile chemical group detected in livestock protein materials, such as a pork and a beef, was ketones. The pork sample showed specific flavors, such as alcoholic, green, and fruity, while a beef presented distinctive flavor, including creamy, fruity, and alcoholic. Based on the results, this research provided the understanding of the flavor aspects of diverse protein materials.

Optimizing the fermentation parameters in the Lactic Acid Fermentation of Legume-based Beverages- a statistically based fermentation

BACKGROUND

The market for beverages is highly changing within the last years. Increasing consumer awareness towards healthier drinks led to the revival of traditional and the creation of innovative beverages. Various protein-rich legumes were used for milk analogues, which might be also valuable raw materials for refreshing, protein-rich beverages. However, no such applications have been marketed so far, which might be due to unpleasant organoleptic impressions like the legume-typical "beany" aroma. Lactic acid fermentation has already been proven to be a remedy to overcome this hindrance in consumer acceptance.

RESULTS

In this study, a statistically based approach was used to elucidate the impact of the fermentation parameters temperature, inoculum cell concentration, and methionine addition on the fermentation of lupine- and faba bean-based substrates. A total of 39 models were found and verified. The majority of these models indicate a strong impact of the temperature on the reduction of aldehydes connected to the "beany" impression (e.g., hexanal) and on the production of pleasantly perceived aroma compounds (e.g., β-damascenone). Positively, the addition of methionine had only minor impacts on the negatively associated sulfuric compounds methional, dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide. Moreover, in further fermentations, the time was added as an additional parameter. It was shown that the strains grew well, strongly acidified the both substrates (pH ≤ 4.0) within 6.5 h, and reached cell counts of > 9 log10 CFU/mL after 24 h. Notably, most of the aldehydes (like hexanal) were reduced within the first 6-7 h, whereas pleasant compounds like β-damascenone reached high concentrations especially in the later fermentation (approx. 24-48 h).

CONCLUSIONS

Out of the fermentation parameters temperature, inoculum cell concentration, and methionine addition, the temperature had the highest influence on the observed aroma and taste active compounds. As the addition of methionine to compensate for the legume-typical deficit did not lead to an adverse effect, fortifying legume-based substrates with methionine should be considered to improve the bioavailability of the legume protein. Aldehydes, which are associated with the "beany" aroma impression, can be removed efficiently in fermentation. However, terminating the process prematurely would lead to an incomplete production of pleasant aroma compounds.

Identification of key aroma compounds of faba beans (Vicia faba) and their development during germination - a SENSOMICS approach

Faba beans are a promising source of valuable plant protein. However, their aroma impression is often a hindrance for the use in a broad range of food products. To develop mitigation strategies, a deeper insight into the faba bean aroma is required. Therefore, for the first time, the SENSOMICS concept was applied. First, 52 aroma active compounds in raw and malted faba beans were identified and semi-quantitatively preselected by aroma extract dilution analysis. Afterwards, the aroma compounds were quantified, odor activity values were calculated, and the 17 prominent odors were selected and used in the reconstitution of the faba bean aroma. Seven statistically significant key aroma compounds 3-methylbutanoic acid, (E)-non-2-enal, hexanal, methional, 3-methylbutanal, sotolon, and 2-methylbutan-1-ol were identified in omission experiments. Finally, their development upon malting was studied. To conclude, by knowing the key aroma compounds, specific mitigation strategies can be developed, which facilitates the broader use of faba beans.

Impact of emerging food processing technologies on structural and functional modification of proteins in plant-based meat alternatives: An updated review

In the past decade, the plant-based meat alternative industry has grown rapidly due to consumers' demand for environmental-friendly, nutritious, sustainable and humane choices. Consumers are not only concerned about the positive relationship between food consumption and health, they are also keen on the environmental sustainability. With such increased consumers' demand for meat alternatives, there is an urgent need for identification and modification of protein sources to imitate the functionality, textural, organoleptic and nutritional characteristics of traditional meat products. However, the plant proteins are not readily digestible and require more functionalization and modification are required. Proteins has to be modified to achieve high quality attributes such as solubility, gelling, emulsifying and foaming properties to make them more palatable and digestible. The protein source from the plant source in order to achieve the claims which needs more high protein digestibility and amino acid bioavailability. In order to achieve these newer emerging non-thermal technologies which can operate under mild temperature conditions can reach a balance between feasibility and reduced environmental impact maintaining the nutritional attributes and functional attributes of the proteins. This review article has discussed the mechanism of protein modification and advancements in the application of non-thermal technologies such as high pressure processing and pulsed electric field and emerging oxidation technologies (ultrasound, cold plasma, and ozone) on the structural modification of plant-based meat alternatives to improve, the techno-functional properties and palatability for successful food product development applications.

Flavour by design: food-grade lactic acid bacteria improve the volatile aroma spectrum of oat milk, sunflower seed milk, pea milk, and faba milk towards improved flavour and sensory perception

BACKGROUND

The global market of plant-based milk alternatives is continually growing. Flavour and taste have a key impact on consumers' selection of plant-based beverages. Unfortunately, natural plant milks have only limited acceptance. Their typically bean-like and grassy notes are perceived as "off-flavours" by consumers, while preferred fruity, buttery, and cheesy notes are missing. In this regard, fermentation of plant milk by lactic acid bacteria (LAB) appears to be an appealing option to improve aroma and taste.

RESULTS

In this work, we systematically studied LAB fermentation of plant milk. For this purpose, we evaluated 15 food-approved LAB strains to ferment 4 different plant milks: oat milk (representing cereal-based milk), sunflower seed milk (representing seed-based milk), and pea and faba milk (representing legume-based milk). Using GC‒MS analysis, flavour changes during anaerobic fermentations were studied in detail. These revealed species-related and plant milk-related differences and highlighted several well-performing strains delivered a range of beneficial flavour changes. A developed data model estimated the impact of individual flavour compounds using sensory scores and predicted the overall flavour note of fermented and nonfermented samples. Selected sensory perception tests validated the model and allowed us to bridge compositional changes in the flavour profile with consumer response.

CONCLUSION

Specific strain-milk combinations provided quite different flavour notes. This opens further developments towards plant-based products with improved flavour, including cheesy and buttery notes, as well as other innovative products in the future. S. thermophilus emerged as a well-performing strain that delivered preferred buttery notes in all tested plant milks. The GC‒MS-based data model was found to be helpful in predicting sensory perception, and its further refinement and application promise enhanced potential to upgrade fermentation approaches to flavour-by-design strategies.

Identification of a Bitter Peptide Contributing to the Off-Flavor Attributes of Pea Protein Isolates

The aversive bitter taste of pea protein ingredients limits product acceptability. Compounds contributing to the bitter perception of pea protein isolates were investigated. Off-line multi-dimensional sensory-guided preparative liquid chromatography fractionation of a 10% aqueous PPI solution revealed one main bitter compound that was identified by Fourier transform ion cyclotron resonance mass spectrometry and de novo tandem mass spectrometry (MS/MS) sequencing as the 37 amino acid peptide PA1b from pea albumin and further confirmed by synthesis. Quantitative MS/MS analysis reported that the concentration of the bitter peptide was 129.3 mg/L, which was above the determined bitter sensory threshold value of 3.8 mg/L and in agreement with the perceived bitter taste of the sample.

Development and Chemical-Sensory Characterization of Chickpeas-Based Beverages Fermented with Selected Starters

Legume protein ingredients are receiving continuous interest for their potential to formulate plant-based dairy analogs. In this study, a legume-based slurry was produced from an Apulian black chickpeas (BCP) protein concentrate and fermented with three starter cultures, Streptococcus thermophilus (ST), a co-culture of ST with Lactococcus lactis (STLL) and a co-culture of ST with Lactobacillus plantarum (STLP). The effect of fermentation on the biochemical, texture and sensorial parameters was evaluated. The same beverage without inoculum was used as a control (CTRL). All the obtained fermented beverages were characterized by high protein (120.00 g kg−1) and low-fat contents (17.12 g kg−1). Fermentation contributed to a decrease in the contents of phytic acid by 10 to 79% and saturated fatty acids by 30 to 43%, with the STLP fermentation exercising the major effect. The three culture starters influenced the texture and sensorial attributes and the profile of the volatile compounds differently. Fermentation increased the lightness, consistency, cohesivity and viscosity of the formulated beverages. On a sensorial level, STLL had a major effect on the acidity, sourness and astringency, while both ST and STLP affected the creaminess, solubility and stickiness. Legumes and grass aromas were masked in LAB-fermented samples, probably due to a new VOC formation. The functional properties of LAB fermentation, along with the high protein content of the black chickpeas concentrate, provide the opportunity to formulate a clean label and safe plant-based fermented beverage with higher nutritional value compared to the others currently found in the market.

Fermentation Conditions Affect the Synthesis of Volatile Compounds, Dextran, and Organic Acids by Weissella confusa A16 in Faba Bean Protein Concentrate

Fermentation with Weissella confusa A16 could improve the flavor of various plant-based sources. However, less is known about the influence of fermentation conditions on the profile of volatile compounds, dextran synthesis and acidity. The present work investigates the synthesis of potential flavor-active volatile compounds, dextran, acetic acid, and lactic acid, as well as the changes in viscosity, pH, and total titratable acidity, during fermentation of faba bean protein concentrate with W. confusa A16. A Response Surface Methodology was applied to study the effect of time, temperature, dough yield, and inoculum ratio on the aforementioned responses. Twenty-nine fermentations were carried out using a Central Composite Face design. A total of 39 volatile organic compounds were identified: 2 organic acids, 7 alcohols, 8 aldehydes, 2 alkanes, 12 esters, 3 ketones, 2 aromatic compounds, and 3 terpenes. Long fermentation time and high temperature caused the formation of ethanol and ethyl acetate and the reduction of hexanal, among other compounds linked to the beany flavor. Levels of dextran, acetic acid, and lactic acid increased with increasing temperature, time, and dough yield. Optimal points set for increased dextran and reduced acidity were found at low temperatures and high dough yield. Such conditions would result in hexanal, ethyl acetate and ethanol having a relative peak area of 35.9%, 7.4%, and 4.9%, respectively.

Effect of biotic stress on the presence of secondary metabolites in field pea grains

BACKGROUND

The presence of secondary metabolites responsible for off-flavours in peas may influence consumers' acceptance. These undesirable compounds may increase due to biotic stress or cultivar. Therefore, grains from two pea (Pisum sativum L.) cultivars (Crécerelle and Firenza) exposed to biotic stress were studied in terms of protein content, electrophoretic polypeptide profile, lipoxygenase activity, saponin content and volatile compounds.

RESULTS

No differences were observed in the electrophoretic polypeptide profile of pea samples across cultivar or biotic stress. The cultivar noticeably affected the volatile compounds and lipoxygenase activity. The biotic stress significantly increased the saponin content.

CONCLUSION

The cultivar showed more noticeable impact on the presence of off-flavour compounds than the biotic stress. The development of pea protein ingredients needs the thorough choice of raw materials in terms of cultivar and control of biotic stress in order to ensure acceptance by consumers. © 2022 Society of Chemical Industry.

Modulation of Metabolome and Overall Perception of Pea Protein-Based Gels Fermented with Various Synthetic Microbial Consortia

Moving to a more sustainable food system requires increasing the proportion of plant protein in our diet. Fermentation of plant product could thus be used to develop innovative and tasty food products. We investigated the impact of fermentation by synthetic microbial consortia (SMC) on the perception of pea protein-based gels, giving possible keys to better understand the origin of sensory perception (e.g., beany, bitter). Two types of pea gels, containing (i) 100% pea proteins and (ii) 50% pea proteins/50% milk proteins, were fermented with three different SMC. Major species developing in both types of gels were Geotrichum candidum, Lactococcus lactis, and Lactobacillus rhamnosus. In pea gels, sensory analyses revealed that bitterness increased after fermentation, which could be due to hydrophobic amino acids resulting from protein hydrolysis, but also decreased pea note intensity in pea gels. In mixed gels, pea perception was similar whatever the SMC, whereas cheesy perception increased. Olfactometry experiments revealed that some specific “green” aroma compounds, responsible for green off-note, were suppressed/reduced by fermentation. The data presented investigated to which extent the design of SMC, together with gels composition (pea gels versus mixed gels), could modulate sensorial perception and drive consumer acceptability.

Chemical Analysis of Commercial White Wines and Its Relationship with Consumer Acceptability

White wine consists of numerous chemical constituents such as volatile and nonvolatile compounds including organic acids and polyphenols, which can affect aroma and flavor profiles. In addition to the enological factors, chemical analysis of commercial wines is also important for understanding consumer perception. Volatile compounds are major contributors to wine aroma. Nonvolatile compounds affect the flavor of wine, through acidity, sweetness, bitterness, and astringency. The volatile aroma profiles of 12 commercial white wines were analyzed using headspace solid-phase microextraction (HS-SPME), with gas chromatography–mass spectrometry (GC–MS). High-performance liquid chromatography (HPLC) and a Y15 automatic analyzer were used to identify and quantify 10 polyphenols and 12 other target nonvolatile compounds. Sensory evaluation of sample wines was conducted by wine consumers. White wines were distinguished based on volatile and nonvolatile compositions. A total of 33 volatile compounds and 23 nonvolatile compounds were analyzed. Seven volatile compounds were correlated with consumer acceptability. Sugars are positively correlated with consumer preference, while nonvolatile substances such as acetic acid and catechins are negatively correlated with consumer preference. These results might further our understanding of the relationship between the chemical composition and consumer preferences in commercial wines.

Aroma of peas, its constituents and reduction strategies - Effects from breeding to processing

Peas as an alternative protein source have attracted a great deal of interest from the food industry and consumers in recent years. However, pea proteins usually do not taste neutral and exhibit a distinct flavor, often characterized as "beany". This is usually contrasted by the food industry's desire for sensory neutral protein sources. In this review, we highlight the current state of knowledge about the aroma of peas and its changes along the pea value chain. Possible causes and origins, and approaches to reduce or eliminate the aroma constituents are presented. Fermentative methods were identified as interesting to mitigate undesirable off-flavors. Major potential has also been discussed for breeding, as there appears to be a considerable leverage at this point in the value chain: a reduction of plant-derived flavors, precursors, or substrates involved in off-flavor evolution could prevent the need for expensive removal later.

The Sensory Profiles of Flatbreads Made from Sorghum, Cassava, and Cowpea Flour Used as Wheat Flour Alternatives

Sorghum, cowpea, and cassava are underutilised gluten-free sources of flour that have the potential to be used in bread products in sub-Saharan Africa. Excessive wheat imports affect the economies of countries in sub-Saharan Africa, driving the search for wheat flour alternatives. To extend the use of sorghum, cowpea, and cassava flours toward bread production, it is vital that the sensory properties of these flours are better understood. A trained sensory panel evaluated and described the sensory properties of flatbread models prepared from red non-tannin sorghum, fractions (whole and dehulled) of two cowpea varieties, cassava starch, and designated flour composites. The composites were prepared using cassava starch and sorghum flour at 0%, 35%, and 70%, respectively, with 30% cowpea flour. The addition of sorghum intensified sorghum aroma in flatbread, while cowpea flours contributed a beany flavour. Flatbreads from cassava-cowpea composites had a chewier and rubberier mouthfeel, an intense fermented aroma and flavour, and a sour aftertaste compared to single flours, but were most similar to the wheat flatbread, with a residual beany flavour. Information from this study can guide food product developers toward developing new bread products from sorghum, cassava, and cowpea composite flours, thereby moving Africa towards a more sustainable food system. Further research on the effects of the sensory characteristics on consumer liking of the flatbreads is needed.

Flavour stability of sterilised chickpeas stored in pouches

The increasing need for sustainable food choices places a demand on developing palatable foods from lower impact production and with a suitable shelf-life. In this context, knowledge of the sensory properties of whole sterilised chickpeas is required to be able to make them more attractive to the consumers. The sensory quality of chickpeas is largely dependent on the aroma and flavour, which can be influenced by storage conditions. In this study, sterilised chickpeas in two different packaging materials with different oxygen permeabilities, stored up to 52 weeks at ambient temperature (20 °C) were investigated using both descriptive sensory profiling and gas chromatography – mass spectrometry – olfactometry analysis (GC-MS-O). During storage, intense, sulphury and meat-like aromas decreased in intensity, while with longer storage time hay-like, green-like and potato-like flavours and aromas became more apparent. A total of 40 odour-active volatiles were detected, of which some had properties reminiscent of the chickpea flavour profiles. However, no clear relationships could be established between these odorants and the sensory changes observed during storage by descriptive sensory analysis. It was concluded that, significant changes in the sensory attributes of sterilised chickpeas occurred during 52 weeks of storage, but that packaging material does not seem to largely influence the sensory attributes during storage.

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Significant sensory changes occur in sterilised chickpeas during 52 weeks storage.

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40 odour-active volatiles are detected in the sterilised chickpeas.

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Sulphur compounds formed during sterilisation change during storage.

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Hay and green attributes are perceived more intense with increased storage time.

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Oxygen permeability of packaging does not impact the sensory quality during storage.

Potential of Chickpea Flours with Different Microstructures as Multifunctional Ingredient in an Instant Soup Application

Chickpea flours are an interesting multifunctional ingredient for different food products. This study investigated the potential of differently processed chickpea flours as alternative thickening agents in an instant soup recipe, replacing potato starch. Dry instant soup powders were compared on bulk density and powder flowability, whereas prepared liquid instant soups were studied in terms of rheological behaviour (as influenced by microstructure) and volatile composition. The chickpea-flour-containing soup powders possessed similar powder flowability to a reference powder but were easier to mix and will potentially result in reduced blockages during filling. For prepared liquid instant soups, similar viscosities were reached compared to the potato starch reference soup. Nevertheless, the chickpea-flour-containing soups showed higher shear thinning behaviour due to the presence of larger particles and the shear induced breakdown of particle clusters. Flavour compounds from the soup mix interacted with chickpea flour constituents, changing their headspace concentrations. Additionally, chickpea flours introduced new volatile compounds to the soups, such as ketones, aldehydes, alcohols, and sulphur compounds, which can possibly alter the aroma and flavour. It was concluded that chickpea flours showed excellent potential as alternative thickening ingredient in instant soups, improving the protein, mineral and vitamin content, and the powder flowability of the soups, although the flavour of the soups might be affected by the changes in volatile profiles between the soups.

Effect of Revtech thermal processing on volatile organic compounds and chemical characteristics of split yellow pea (Pisum sativum L.) flour

Yellow pea (Pisumsativum L.) is an economically rich source of nutrients with health-promoting effects. However, the consumption of pea ingredients is minimal due to their off-flavor characteristics. The present study investigated the effect of Revtech heat treatment on the chemical profile and volatile compounds in split yellow pea flour. Revtech treatment (RT) was applied at 140°C with a residence time of 4 min in dry condition (RT 0%) and in the presence of 10% steam (RT 10%). Both thermal treatments resulted in a significant reduction (p < 0.05) in lipoxygenase activity and the concentration of key beany-related odors such as heptanal, (E)-2-heptenal, 1-octen-3-ol, octanal, and (E)-2-octenal. In addition, RT 10% resulted in a significant reduction in pentanal, 1-penten-3-ol, hexanal, and 1-hexanol compared to untreated flour. The content of known precursors of lipoxygenase such as linoleic and linolenic acids was found in higher concentrations in heat-treated flours, indicating the efficacy of Revtech technology in minimizing the degradation of polyunsaturated fatty acids. No significant changes in the amino acid composition or the 29 selected phenolic compounds in pea flours were observed with Revtech processing except for two compounds, caffeic acid and gallocatechin, which were found at higher concentrations in RT 0%. PRACTICAL APPLICATION: Thermal processing of split yellow pea flours at 140°C using Revtech technology successfully decreased the concentrations of volatile compounds responsible for beany off-flavor while improving the nutritional quality of studied yellow pea flours. These results provide valuable information to the food industry for developing novel pulse-based products with enhanced sensory characteristics.

QTL Mapping of Seed Quality Traits Including Cooking Time, Flavor, and Texture in a Yellow Dry Bean (Phaseolus vulgaris L.) Population

Manteca yellow dry beans (Phaseolus vulgaris L.) have many quality traits that appeal to consumers, including fast cooking times, creamy texture, and sweet, buttery flavor. They are native to Chile and consumed in regions of South America and Africa but are largely unfamiliar to United States consumers. While cooking time, flavor, and texture have not been prioritized in United States dry bean breeding programs, genetic variability exists such that these traits could be addressed through breeding. In this study, a recombinant inbred line (RIL) population was developed from a cross between Ervilha (Manteca) and PI527538 (Njano), yellow dry beans with contrasting cooking time and sensory attributes. The population and parents were grown for 2 years in Michigan and evaluated for cooking time and sensory attribute intensities, including total flavor, beany, vegetative, earthy, starchy, sweet, bitter, seed-coat perception, and cotyledon texture. Cooking time ranged 19-34 min and exhibited high broad-sense heritability (0.68). Sensory attribute intensities also exhibited variation among RILs, although broad-sense heritability was low, with beany and total flavor exhibiting the highest (0.33 and 0.27). A linkage map of 870 single nucleotide polymorphisms markers across 11 chromosomes was developed for quantitative trait loci (QTL) mapping, which revealed QTL for water uptake (3), cooking time (6), sensory attribute intensities (28), color (13), seed-coat postharvest non-darkening (1), seed weight (5), and seed yield (2) identified from data across 2 years. Co-localization was identified for starchy, sweet, and seed-coat perception on Pv01; for total flavor, beany, earthy, starchy, sweet, bitter, seed-coat perception, cotyledon texture, and color on Pv03; water uptake and color on Pv04; total flavor, vegetative, sweet, and cotyledon texture on Pv07; cooking time, starchy, sweet, and color on Pv08; and water uptake, cooking time, total flavor, beany, starchy, bitter, seed-coat perception, cotyledon texture, color, and seed-coat postharvest non-darkening on Pv10. The QTL identified in this work, in particular CT8.2 and CT10.2, can be used to develop molecular markers to improve seed quality traits in future dry bean varieties. Considering yellow dry beans already excel in quality and convenience, they might be an ideal market class to signal a new focus on consumer-valued traits in the United States.

Sprouting improves the flavour quality of faba bean flours

Flours were made from the sprouted seeds of the low- and high-tannin faba bean cultivars Fabelle, FB9-4, Snowbird, and Snowdrop. Headspace measurements on sprouted flours found the most favourable aroma profiles following 48 h sprouting and 24 h drying at 60 °C. Lipoxygenase activity, and the tannin, protein, and moisture contents were determined for unsprouted and sprouted faba bean flours. Lipoxygenase activity was higher in sprouted seeds before drying. Protein content increased after sprouting, whereas the tannin content decreased, especially for high-tannin varieties. Key volatile flavour compounds of faba bean flours included pentanal, hexanal, heptanal, octanal, nonanal, decanal, 1-hexanol, 1-octen-3-ol, 3-methylbutanal, phenyl acetaldehyde, 3-methylbutyric acid, d-limonene, β-linalool, menthol, and estragole; these include oxidative degradation products of oleic, linoleic, and some amino acids. An overall flavour improvement was achieved after germination, as indicated by a decrease in bitter compounds (tannins) and beany flavours (hexanal, nonanal, 2-heptanone, and 2-pentylfuran).

Toward a comprehensive understanding of ultracentrifugal milling on the physicochemical properties and aromatic profile of yellow pea flour

Yellow pea (Pisum sativum L., YP) grain is generally milled into flour for further processing or direct consumption. However, the comprehensive relationship between milling configurations and YP flour properties remains unclear. The aim of this study is to investigate the effect of configurations (screen aperture size and rotor speed) of ultracentrifugal mill on the physicochemical properties and aromatic profiles of YP flours. Starch damage, morphology, particle size distribution, pasting, thermal property, and aromatic profiles of YP flours were studied. Results show that starch damage increased significantly as the screen aperture size decreased. The YP flour produced with a 500 µm aperture screen had the most stable pasting and thermal properties. With untargeted metabolomic approaches, 2-ethyl-1-hexanol could potentially be applied as an aroma maker to distinguish if an excessive milling or inappropriate configurations of ultracentrifugal mill are applied. This work has furnished fundamentals for the milling and application of YP flour.

Genome-based selection and application of food-grade microbes for chickpea milk fermentation towards increased L-lysine content, elimination of indigestible sugars, and improved flavour

Background

Plant-based milk alternatives are more popular than ever, and chickpea-based milks are among the most commercially relevant products. Unfortunately, limited nutritional value because of low levels of the essential amino acid l-lysine, low digestibility and unpleasant taste are challenges that must be addressed to improve product quality and meet consumer expectations.

Results

Using in-silico screening and food safety classifications, 31 strains were selected as potential l-lysine producers from approximately 2,500 potential candidates. Beneficially, 30% of the isolates significantly accumulated amino acids (up to 1.4 mM) during chickpea milk fermentation, increasing the natural level by up to 43%. The best-performing strains, B. amyloliquefaciens NCC 156 and L. paracasei subsp. paracasei NCC 2511, were tested further. De novo lysine biosynthesis was demonstrated in both strains by ¹³C metabolic pathway analysis. Spiking small amounts of citrate into the fermentation significantly activated l-lysine biosynthesis in NCC 156 and stimulated growth. Both microbes revealed additional benefits in eliminating indigestible sugars such as stachyose and raffinose and converting off-flavour aldehydes into the corresponding alcohols and acids with fruity and sweet notes.

Conclusions

B. amyloliquefaciens NCC 156 and L. paracasei subsp. paracasei NCC 2511 emerged as multi-benefit microbes for chickpea milk fermentation with strong potential for industrial processing of the plant material. Given the high number of l-lysine-producing isolates identified in silico, this concept appears promising to support strain selection for food fermentation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12934-021-01595-2.

The effect of short-term storage temperature on the key headspace volatile compounds observed in Canadian faba bean flour

The odour emitted from the high-tannin fab bean flour (Vicia faba var. minor), was characterized by headspace solid-phase microextraction/gas chromatography-mass spectrometry (HS-SPME/GC–MS). The relative odour activity value (ROAV) was used to monitor the changes in key volatile compounds in the flour during short-term storage at different temperature conditions. The key flavour compounds of freshly milled flour included hexanal, octanal, nonanal, decanal, 3-methylbutanal, phenyl acetaldehyde, (E)-2-nonenal, 1-hexanol, phenyl ethyl alcohol, 1-octen-3-ol, β-linalool, acetic acid, octanoic acid, and 3-methylbutyric acid; these are oxidative degradation products of unsaturated fatty acids and amino acids. Despite the low lipid content of faba beans, the abundances of aldehydes arising during room temperature storage greatly contributed to the flavour of the flour due to their very low odour thresholds. Two of the key volatiles responsible for beany flavour in flour (hexanal, nonanal) increased greatly after 2 weeks of storage at room temperature or under refrigerated conditions. These volatile oxidation products may arise as a result of enzymatic activity on unsaturated fatty acids, and was seen to be arrested by freezing the flour.

Genetic variability and genome-wide association analysis of flavor and texture in cooked beans (Phaseolus vulgaris L.)

Cooked bean flavor and texture vary within and across 20 Andean seed types; SNPs are significantly associated with total flavor, beany, earthy, starchy, bitter, seed-coat perception, and cotyledon texture. Common dry beans are a nutritious food recognized as a staple globally, but their consumption is low in the USA. Improving bean flavor and texture through breeding has the potential to improve consumer acceptance and suitability for new end-use products. Little is known about genetic variability and inheritance of bean sensory characteristics. A total of 430 genotypes of the Andean Diversity Panel representing twenty seed types were grown in three locations, and cooked seeds were evaluated by a trained sensory panel for flavor and texture attribute intensities, including total flavor, beany, vegetative, earthy, starchy, sweet, bitter, seed-coat perception, and cotyledon texture. Extensive variation in sensory attributes was found across and within seed types. A set of genotypes was identified that exhibit extreme attribute intensities generally stable across all three environments. seed-coat perception and total flavor intensity had the highest broad-sense heritability (0.39 and 0.38, respectively), while earthy and vegetative intensities exhibited the lowest (0.14 and 0.15, respectively). Starchy and sweet flavors were positively correlated and highest in white bean genotypes according to principal component analysis. SNPs associated with total flavor intensity (six SNPs across three chromosomes), beany (five SNPs across four chromosomes), earthy (three SNPs across two chromosomes), starchy (one SNP), bitter (one SNP), seed-coat perception (three SNPs across two chromosomes), and cotyledon texture (two SNPs across two chromosomes) were detected. These findings lay a foundation for incorporating flavor and texture in breeding programs for the development of new varieties that entice growers, consumers, and product developers alike.

Impact of lactic acid fermentation on sensory and chemical quality of dairy analogues prepared from lupine (Lupinus angustifolius L.) seeds

Lupine (Lupinus sp.) is a valuable source of plant proteins. There is little knowledge on the impact of food processing on composition and sensory properties of lupine products. In this research, we investigated the impact of fermentation with five starters of lactic acid bacteria on the sensory quality and flavor-active compounds in dairy analogues prepared from sweet lupine (Lupinus angustifolius L.). The sensory qualities of unfermented and fermented products were studied with generic descriptive analysis and affective tests. Acids and sugars were analyzed with GC-FID and volatiles with HS-SPME-GC-MS and GC-O. Fermentation increased sourness and 'vinegar' odor and reduced the 'beany' odor and flavor as well as the unpleasantness of flavor. Formation of volatiles during the fermentation was dependent on the starters. However, all fermentations increased the contents of lactic, acetic, and hexanoic acids, while reducing the contents of hexanal, described as 'grassy' in the unfermented lupine sample.

Combining solid dispersion-based spray drying with cyclodextrin to improve the functionality and mitigate the beany odor of pea protein isolate

The beany flavor of pea protein limits its application in the food industry. This study aimed at addressing this problem by combining the advantages of solid-based spray drying technique and the ability of cyclodextrins (CD) to entrap volatiles. Pea protein isolates (PPI) was extracted by alkaline extraction-isoelectric precipitation, followed by co-spray drying with CD. The resulted PPI-CD showed no major structure changes. HS-SPME-GC-MS coupled to untargeted metabolomics successfully identified 23 aroma compounds that represent the different odorants among PPI-control, physically mixed PPI-CD, and co-spray dried PPI-CD samples. Heat map analysis also showed a remarkable beany odor mitigation effect upon the addition of CD, which was further proved to be due to CD entrapping aroma compounds during spray drying. In the meantime, the functional attributes of PPI-CD were not adversely impacted by the addition of CD.

Impact of temperature and water activity on the aroma composition and flavor stability of pea (Pisum sativum) protein isolates during storage

Flavor stability of pea protein isolates (PPIs) during storage was investigated. Two commercial PPIs were stored at three water activities (0.128-0.501) under refrigerated (7 °C) and accelerated (37 °C) temperatures for 12 weeks. Eleven aroma compounds were monitored by gas chromatography-tandem mass spectrometry (GC/MS/MS) and results revealed significant changes in the aroma concentrations among the PPI samples during storage. In agreement with the chemical changes, significant differences in orthonasal aroma profiles were demonstrated using a sensory difference-from-control test. The sample stored under accelerated storage temperature (37 °C) and at the highest water activity showed the greatest degree of aroma change. An aroma recombination sensory study indicated the generation of two specific compounds, 1-octen-3-ol and nonanal, along with the degradation of 2-4-decadienal resulted in sensory changes during storage indicating lipid oxidation was the main mechanism of flavor instability in the PPI samples.

Conjugation of Pea Protein Isolate via Maillard-Driven Chemistry with Saccharide of Diverse Molecular Mass: Molecular Interactions Leading to Aggregation or Glycation

Diverse saccharides are effectively grafted to pea protein isolate (PPI) through Maillard-driven chemistry. The development of conjugates (glyco-PPI) was validated by ultraviolet-visible spectroscopy, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and size exclusion chromatography-high performance liquid chromatography. The impact of covalent conjugation on color development, structural modification, solubility, thermal stability, and volatiles of glycoprotein was examined. The protein solubility was improved, while its thermal stability seemed to be negatively influenced. The principle proposed involves Maillard-driven generation of the conjugates, which enhanced the surface hydrophilicity and unfolding of protein architecture of glyco-PPI. Additionally, both molecular mass and the grafted number of saccharides played a vital role in determining the solubility and thermal stability of glyco-PPI. Protein tends to denature at reaction conditions of 80 °C and pH 10.0, and its cross-linkage occurred in the aqueous system. The two potential routes of molecular interactions between PPI and saccharides were denaturation and glycation or self-cross-linkage. Flavor profile alteration of glycoprotein before and after conjugation was depicted, and relevant off-odors were quantified via headspace solid-phase microextraction gas chromatography-mass spectrometry. These outcomes could furnish valuable in-depth information for dictating functionalities of plant-based protein for food application.

Development of a Sensory Flavor Lexicon for Mushrooms and Subsequent Characterization of Fresh and Dried Mushrooms

Mushrooms are a nutritious versatile ingredient in many food products. They are low in calories and have various potential medicinal properties as well. Surprisingly, little research on their descriptive sensory properties has been conducted. The objectives of this study were to a) establish a descriptive sensory flavor lexicon for the evaluation of fresh, dried, and powdered mushrooms and 2) use that lexicon to compare a selection of different mushrooms of various species and in fresh dried and powdered forms. A lexicon for describing mushroom was developed using a consensus profile method. A highly trained, descriptive sensory panel identified, defined, and referenced 27 flavor attributes for commercially available mushroom samples prepared as “meat” and broth. Attributes could be grouped in categories such as musty (dusty/papery, earthy/humus, earthy/damp, earthy/potato, fermented, leather (new), leather (old), mold/cheesy, moldy/damp, mushroomy), and other attributes such as fishy, shell fish, woody, nutty, brown, green, cardboard, burnt/ashy, potato, umami, protein (vegetable), yeasty, bitter, salty, sweet aromatics, sour, and astringent. Samples were then tested in three replications and mean values were compared statistically. In addition, principal component analysis was used to understand the characteristics of mushrooms evaluated. Dried mushrooms showed bitter, burnt, musty/dusty, astringent, old leather, and fresh mushroom characteristics and fresh mushroom showed umami, sweet, earthy/potato, earthy/damp, yeasty, and fermented. Mushrooms were grouped and differentiated in similar ways regardless of whether they were tested as broth or “meat”. Mushroom growers, product developers, chefs and other culinary professionals, sensory scientists, researchers, the food industry, and ultimately consumers will benefit from this lexicon describing a wide variety of mushroom flavor properties.

Using Multiple Sensory Profiling Methods to Gain Insight into Temporal Perceptions of Pea Protein-Based Formulated Foods

The food industry is focused on creating plant-based foods that incorporate pea protein isolates. However, pea protein isolates are often described as having persistent beany, bitter, and astringent notes that can decrease the desirability of the resulting foods and make static sensory profiling difficult. To obtain more realistic descriptions of the sensory experiences associated with this category of products, researchers should consider using temporal methods and multi-intake methods, which allow consumers to evaluate whole food portions. This study aimed to understand better how product composition affected the sensory perception of pea protein-based beverages using three different sensory profiling methods. Particular focus was placed on beany, bitter, and astringent notes. Twelve pea protein-based beverages were formulated; they varied in pea protein type (pellet vs. isolate) and their content of gellan gum, salt, sunflower oil, sugar, and soy lecithin. They were evaluated by 16 trained panelists using three sensory profiling methods: static block profiling, mono-intake temporal dominance of sensations (TDS) profiling, and multi-intake TDS profiling. The static block and mono-intake TDS profiling methods yielded complementary results about the impact of beverage composition on attribute perceptions. Static block profiling revealed that beaniness was mainly affected by gellan gum and oil content and that bitterness and astringency were mainly affected by protein type and gellan gum content. Mono-intake TDS profiling highlighted the dynamics of beaniness and the strong persistence of astringency, and its results suggested that higher gellan gum and salt contents could limit this persistence. Multi-intake TDS profiling found that, throughout the consumption of a full product portion, beaniness and bitterness decreased, indicating an adaptation effect, while fattiness increased, indicating a build-up effect. This study has increased the understanding of how pea protein-based beverages are perceived under conditions that more closely resemble those associated with real-life consumption. It has also revealed how product formulation can reduce bitterness and astringency.

Changes in odor characteristics of pulse protein isolates from germinated chickpea, lentil, and yellow pea: Role of lipoxygenase and free radicals

In this study, pulse protein isolates (PPIs) were extracted from 0, 1, 3, and 5 days germinated chickpea, lentil, and yellow pea flours by alkaline extraction-isoelectric precipitation method. The germination time had negligible impact on the proximate composition of PPIs. In total, 67 volatiles in PPIs were identified via HS-SPME-GC-MS/O. Among all the identified volatile components, seven of them, including hexanal (11), (E)-2-octen-1-ol (7), (E,Z)-2,6-nonadienal (17), 3-octen-2-one (33), 3,5-octadien-2-one (34), 2-methoxy-3-isopropylpyrazine (56), and 2-methoxy-3-(1-methylpropyl)pyrazine (57), contributed to the beany-related odor of PPIs but much less than that in raw flours. However, the overall beany-related odor of PPIs increased when the germination time exceeded 1 day. Both the activity of lipoxygenase and the free radical populations in PPIs were positively related to the overall beany-related odor. Our findings are crucial for the preparation of germinated pulse proteins with improved functionality but without increasing undesirable odor.

Determining Which Cooking Method Provides the Best Sensory Differentiation of Potatoes

There are many ways to prepare potatoes that each provide a unique set of sensory properties. However, when conducting a descriptive sensory study, it is important to utilize a cooking method that will highlight, and not distract from, the sensory differences among potato samples due to factors such as variety or growing conditions. This study aimed to determine which of five cooking methods results in the best differentiation among potato varieties to recommend a single method for use in future descriptive sensory studies. Five different potato varieties were each prepared using boiling, mashing, baking, frying, and air frying methods. The samples were provided to six highly trained descriptive panelists and evaluated by consensus using a modified high identity traits (HITs) method. Panelists evaluated the aroma, flavor, and texture to develop a list of up to five total HITs per sample. Additionally, panelists scored each sample for degree of difference (DOD) from the control. Based on the HITs profiles and DOD scores, mashing, baking, and air frying methods were all effective in differentiating the samples. Frying and boiling methods introduced too much variation and are not recommended for sample differentiation. Ultimately, the method chosen for future research would depend on the study objectives.

Sensory Improvement of a Pea Protein-Based Product Using Microbial Co-Cultures of Lactic Acid Bacteria and Yeasts

Consumer demands for plant-based products have increased in recent years. However, their consumption is still limited due to the presence of off-flavor compounds, primarily beany and green notes, which are mainly associated with the presence of aldehydes, ketones, furans, and alcohols. To overcome this problem, fermentation is used as a lever to reduce off-flavors. A starter culture of lactic acid bacteria (LAB) was tested in a 4% pea protein solution with one of the following yeasts: Kluyveromyces lactis, Kluyveromyces marxianus, or Torulaspora delbrueckii. The fermented samples were evaluated by a sensory panel. Non-fermented and fermented matrices were analyzed by gas chromatography coupled with mass spectrometry to identify and quantify the volatile compounds. The sensory evaluation showed a significant reduction in the green/leguminous attributes of pea proteins and the generation of new descriptors in the presence of yeasts. Compared to the non-fermented matrix, fermentations with LAB or LAB and yeasts led to the degradation of many off-flavor compounds. Moreover, the presence of yeasts triggered the generation of esters. Thus, fermentation by a co-culture of LAB and yeasts can be used as a powerful tool for the improvement of the sensory perception of a pea protein-based product.

Gum Arabic-Mediated Synthesis of Glyco-pea Protein Hydrolysate via Maillard Reaction Improves Solubility, Flavor Profile, and Functionality of Plant Protein

Pea protein hydrolysate (PPH) is successfully conjugated with gum arabic (GA) through Maillard-driven chemistry. The effect of cross-linking conjugation on the structure, solubility, volatile substances, emulsification, and antioxidative activity of glyco-PPH is investigated, and found to improve all properties. The formation of glyco-PPH is confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Fourier-transform infrared (FTIR), and scanning electron microscopy (SEM). Size exclusion chromatography-multi angle light scattering (SEC-MALS) unveils that the maximum molecular mass of glyco-PPH occurs after 1 day of conjugation and approximately 1.2 mol of gum arabic conjugates on one mole of PPH. Headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) reveals the odor changes of glycoprotein before and after cross-linking. We have also prepared oil-in-water emulsions using glyco-PPH, which have enhanced physical stability against pH changes and chemical stability against lipid oxidation. The mechanism proposed involves Maillard-driven synthesis of the cross-linked PPH-GA conjugates, which increase the surface hydrophilicity and steric hindrance of glyco-PPH. These findings could provide a rational foundation for tailoring the physicochemical properties and functionalities of plant-based protein, which are attractive for food and functional materials applications.

HS-SPME-GC-MS/olfactometry combined with chemometrics to assess the impact of germination on flavor attributes of chickpea, lentil, and yellow pea flours

In this study, volatile component changes of germinated chickpea, lentil, and yellow pea flours over the course of 6 days germination were characterized by HS-SPME-GC-MS/O. In total, 124 volatile components were identified involving 19 odor active components being recorded by GC-O exclusively. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) revealed that lentil and yellow pea flours had the similar aromatic attributes, while the decrease of beany flavor compounds along with the occurrence of unpleasant flavors was detected in chickpea flours upon germination. Six beany flavor markers, including hexanal, (E,E)-2,4-nonadienal, (E,E)-2,4-decadienal, 3-methyl-1-butanol, 1-hexanol, and 2-pentyl-furan, were employed to quantify beany flavor formation in the flours over the course of germination. The results suggested that no significant beany flavor formation or mitigation was appeared after 1 day of germination. The findings are crucial for tailing pulse germination process to enhance the macronutrients without increasing undesirable beany flavor.

Nutritional and sensory quality of composite extruded complementary food

Complementary foods in Ethiopia have nutritional and sensory limitations which can be attributed to cereal-dominated ingredients and lack of appropriate processing techniques. This study aimed to optimize the nutritional and sensory quality of complementary food product through compositing and extrusion of various local ingredients. A constrained D-optimal mixture experiment with 13 runs was designed. Accordingly, 55-65 g/100 g oats, 11-23 g/100 g soybean and 6-11 g/100 g linseed, and a premix of 9.9 g/100 g sugar, 0.6 g/100 g table salt, three g/100 g moringa and 1.5 g/100 g fenugreek were blended and extruded using a co-rotating twin screw extruder with set parameters. Statistical model evaluation and optimization were done using Minitab version 16 software package. There is a statistically significant (p < 0.05) association between the blend of oats and soybean, oats and linseed, soybean and linseed, and the protein, fat, carbohydrate, fiber, ash, β-carotene content as well as aroma, taste, and consistency. On the contrary, there is a no statistically significant (p < 0.05) association between the blends and moisture, energy, and zinc content together with appearance and overall acceptability. The optimal blending ratio was 55.0 g/100 g oats, 21.0 g/100 g soybean, and 9.0 g/100 g linseed plus 15.0 g/100 g premix. Evidence-based selection of locally grown plant-based ingredients, an optimal mixture of these ingredients and optimal processing, can result in a complementary food product with an improved dietary quality for children in low-income settings.

The Importance of Sensory Lexicons for Research and Development of Food Products

A lexicon is a set of standardized vocabularies developed by highly trained panelists for describing a wide array of sensory attributes present in a product. A number of lexicons have been developed to document and describe sensory perception of a variety of food categories.The current review provides examples of recently developed sensory lexicons for fruits and vegetables; grains and nuts; beverages; bakery, dairy, soy and meat products; and foods for animals. Applications of sensory lexicons as an effective communication tool and a guidance tool for new product development processes, quality control, product improvement, measuring changes during product shelf life, and breeding new plant cultivars are also discussed and demonstrated through research in the field.

Novel Fortified Blended Foods: Preference Testing with Infants and Young Children in Tanzania and Descriptive Sensory Analysis

The preference of porridge made from extruded fortified blended foods (FBFs) compared to a current nonextruded product (corn soy blend plus [CSB+]) among infants and young children was studied in Mwanza region, Tanzania. Five extruded, fortified blends were chosen as novel FBFs in this study: (i) corn soy blend 14 (CSB14), (ii) white sorghumFontanelle 4525 soy blend (SSB), (iii) white sorghumFontanelle 4525 cowpea blend (WSC1), (iv) white sorghum738Y cowpea blend (WSC2), and (v) red sorghum217X Burgundy cowpea blend (RSC). Paired preference testing between CSB+ and each novel FBF was conducted using approximately 600 children for each pair. Results showed that infants and young children prefer CSB14 and SSB over CSB+. Children did not show a preference between CSB+ and any of the 3 sorghum cowpea blends (WSC1, WSC2, and RSC) probably because of a distinct beany flavor from cowpea that they were not familiar with. This study indicated that novel FBFs have potential to be used successfully as supplementary food with higher or comparable preference compared to FBFs currently used in food aid programs.

PRACTICAL APPLICATION

Successful novel fortified blended foods (FBFs) can be developed with appropriate nutrition and sensory appeal from indigenous and alternative food sources. Development of such foods requires an understanding not only of the nutritional composition, but also how ingredients impact sensory properties and how they can influence preferences. From this research, novel FBFs from sorghum and cowpea were shown to be equally or preferentially preferred and should be successful. Such information is important for creating new standards and alternative formulations for FBFs.

Sensory Characteristics of Combinations of Phenolic Compounds Potentially Associated with Smoked Aroma in Foods

The sensory characteristics of phenolic compounds combinations were evaluated. A highly trained descriptive panel evaluated combinations of chemicals (two chemicals at a time) containing either one smoky aroma and one non-smoky aroma chemical compound, two smoky aroma chemicals, or two non-smoky aroma chemicals. The non-smoky compounds had been associated with smoke aroma in other studies, but were not found to be smoky when tested individually. Smoked flavor characteristics and intensities were changed significantly when two phenolic compounds were combined. Non-smoky phenolic compounds often contributed the smoked flavor when combined with one smoky phenolic compound or another non-smoky phenolic compound. It is necessary to understand the sensory characteristics of compound combinations as well as individual compounds.