Food off-odor generation, characterization and recent advances in novel mitigation strategies

The pronounced perception of off-odors poses a prevalent issue across various categories of food ingredients and processed products, significantly exerting negative effects on the overall quality, processability, and consumer acceptability of both food items and raw materials. Conventional methods such as brining, marinating, and baking, are the main approaches to remove the fishy odor. Although these methods have shown notable efficacy, there are simultaneously inherent drawbacks that ultimately diminish the processability of raw materials, encompassing alterations in the original flavor profiles, the potential generation of harmful substances, restricted application scopes, and the promotion of excessive protein/lipid oxidation. In response to these challenges, recent endeavors have sought to explore innovative deodorization techniques, including emerging physical processing approaches, the development of high-efficiency adsorbent material, biological fermentation methods, and ozone water rinsing. However, the specific mechanisms underpinning the efficacy of these deodorization techniques remain not fully elucidated. This chapter covers the composition of major odor-causing substances in food, the methodologies for their detection, the mechanisms governing their formation, and the ongoing development of deodorization techniques associated with the comparison of their advantages, disadvantages, and application mechanisms. The objective of this chapter is to furnish a theoretical framework for enhancing deodorization efficiency through fostering the development of suitable deodorization technologies in the future.

Effects of plant polyphenols on lipid oxidation in pea and soy protein solutions

Significant lipid-derived off-flavors hinder broader acceptance and applicability of plant protein ingredients. Polyphenols are strong antioxidants and can react with protein and carbonyl compounds to reduce oxidative off-flavor development. The effects of polyphenols (catechin, tannic acid (TA), grape seed extract (GSE), and green tea extract (GTE)) on lipid oxidation in pea and soy protein solutions were investigated. All polyphenols reduced lipid oxidation products and volatile compound concentration versus their respective controls. TA, GSE, and GTE reduced the secondary products in pea and soy proteins by an average of 75 % and 50 %, respectively, versus controls, compared to catechin's 61 % and 13 %, respectively. The chemical structures of TA, GSE, and GTE likely allowed them to interact more effectively than catechin with proteins, especially lipoxygenase. However, no significant differences between the polyphenols' antioxidant capacities were observed. Thus, polyphenols predominantly reduced lipid oxidation via interactions with proteins, rather than electron transfer or radical quenching.

Comparison of differences in sensory, volatile odour-activity and volatile profile of commercial plant-based meats

Descriptive sensory analysis was paired with temporal check-all-that-apply gas-chromatography olfactometry (TCATA GC-O) to compare differences in perceived flavour and volatile odour activity across a series of commercial plant-based meat analogues (PBMAs) versus conventional beef products. Multiple factor analysis separated PBMAs in two clusters along the first principal axis. The first cluster, rated higher in meaty flavour and odour, also showed higher citation proportions of sulfurous odourants. In contrast, the second cluster, higher in off odour and flavour, had higher citation proportions for fatty / legume odourants. Key odourants correlated with meaty flavour and odour were putatively identified as 2-methyl-3-furanthiol, dimethyl trisulfide, and furfuryl mercaptan while compounds correlated to off flavour and odour were putatively identified as (E,E)-3,5-octadien-2-one, 2-undecanol, and (E,E)-2,4-decadienal. No correspondence was found between PBMA odour-activity and source protein, suggesting that volatile flavour production in PBMAs is derived primarily from exogeneous flavouring materials or precursors rather than the base protein material. Contributions of lipid-protein interactions to overall flavour differences is further suggested by the putative discovery of 5,6-dihydro-2,4,6-trimethyl-4H-1,3,5-dithiazine odour activity in several meat samples profiled.

Faba Bean Flavor Effects from Processing to Consumer Acceptability

Faba beans as an alternative source of protein have received significant attention from consumers and the food industry. Flavor represents a major driving force that hinders the utilization faba beans in various products due to off-flavor. Off-flavors are produced from degradation of amino acids and unsaturated fatty acids during seed development and post-harvest processing stages (storage, dehulling, thermal treatment, and protein extraction). In this review, we discuss the current state of knowledge on the aroma of faba bean ingredients and various aspects, such as cultivar, processing, and product formulation that influence flavour. Germination, fermentation, and pH modulation were identified as promising methods to improve overall flavor and bitter compounds. The probable pathway in controlling off-flavor evolution during processing has also been discussed to provide efficient strategies to limit their impact and to encourage the use of faba bean ingredients in healthy food design.

RuBisCO as a protein source for potential food applications: a review

RuBisCO is a complete protein, widely abundant and recognized as ideal for human consumption. Further, its biochemical composition, organoleptic and physical features mean RuBisCO has potential as a nutritionally beneficial food additive. Nonetheless, despite growing plant-based market trends, there is a lack of information about the applications of this protein. Here, we explored the biochemical features of RuBisCO as a potential food additive and compared it with other plant protein sources currently available. We describe potential advantages, including nutritional content, digestibility, non-allergenicity and, potential bioactivities. Despite the lack of industrial procedures for RuBisCO purification, a growing number of novel methods are emerging, justifying discussion of their feasibilities. Overall, this information can help both researchers and industry to review the use RuBisCO as a sustainable source of protein for plant-based food products or formulation of novel functional foods.

Cyclodextrins produced by cyclodextrin glucanotransferase mask beany off-flavors in plant-based meat analogs

The widening gap between the supply and demand for meat products has increased the need to produce plant-based meat analogs as protein sources. Meat analogs are principally composed of soy-based textured vegetable proteins. Despite ongoing technical developments, one of the unresolved challenges for plant-based meat analogs is the off-flavor from soy, which limits their consumer acceptability. Among the various methods developed for overcoming this challenge, masking the beany flavors with cyclodextrins (CDs) is an attractive, cost-effective, and safe strategy. However, the current established CD treatment method does not meet the requirement for a clean-label. This study aimed to develop more acceptable off-flavor-masking technologies for plant-based patties for modern clean-label preferences using enzymatic methods. We used the cyclodextrin glucanotransferase (CGT), “Amano,” as a commercially available food-grade CGT. The CGT-catalyzed reaction in plant-based patties yielded 17.1 g/L CD. As CGT could yield sufficient CD in the patties, we investigated whether CDs produced by CGT could mask the off-flavors released from the plant-based patties. The CGT-treated patties had significantly lower volatilization amounts of the known beany off-flavor-generating compounds compared to the non-treated patties. Moreover, CGT treatment improved the texture of the patties and increased their water- and oil-holding capacity. As CGT is rendered inactive after cooking, it would not be considered an additive. These findings indicated that CDs produced by the CGT reaction could effectively mask off-flavors of meat analogs and improve their physical properties while meeting clean-label requirements.

Flavor challenges in extruded plant-based meat alternatives: A review

Demand for plant-based meat alternatives has increased in recent years due to concerns about health, ethics, the environment, and animal welfare. Nevertheless, the market share of plant-based meat alternatives must increase significantly if they are to support sustainable food production and consumption. Flavor is an important limiting factor of the acceptability and marketability of plant-based meat alternatives. Undesirable chemosensory perceptions, such as a beany flavor, bitter taste, and astringency, are often associated with plant proteins and products that use them. This study reviewed 276 articles to answer the following five research questions: (1) What are the volatile and nonvolatile compounds responsible for off-flavors? (2) What are the mechanisms by which these flavor compounds are generated? (3) What is the influence of thermal extrusion cooking (the primary structuring technique to transform plant proteins into fibrous products that resemble meat in texture) on the flavor characteristics of plant proteins? (4) What techniques are used in measuring the flavor properties of plant-based proteins and products? (5) What strategies can be used to reduce off-flavors and improve the sensory appeal of plant-based meat alternatives? This article comprehensively discusses, for the first time, the flavor issues of plant-based meat alternatives and the technologies available to improve flavor and, ultimately, acceptability.

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.

Gelation properties and protein conformation of Grass Carp fish ball as influenced by egg white protein

Dried egg white powder (EWP) and purified ovalbumin (OVA, 98%) were used as supplements to improve grass carp (GC) fish balls (FB) quality. The effects of EWP and/or OVA contents on the gel strength, water holding capacity (WHC), moisture migration and distribution, and rheological properties of GC-FB, as well as on myofibrillar protein (MfP) structures in the GC-FB were evaluated. The results showed that with the increase of EWP addition from 0 to 4% (w/w), the gel strength and WHC of the GC-FB samples were increased from 34.28 to 66.63 N×mm, and 83.02 to 88.36%, respectively, but the increases were insignificant between 3% and 4% EWP-added GC-FBs (p>0.05). As the EWP increased, the T₂ relaxation time shifted towards lower values, indicating a general decline in water mobility. The effects of EWP on rheological properties were insignificant. Addition of OVA and/or EWP led to changes in secondary structural units in the FB, with α-helix (27.53%) reaching the highest value in OVA-added GC-FB, β-sheet (46.07%) reaching the highest value in GC-FB, and β-turn (33.54%) reaching the highest value in EWP-added GC-FB, respectively. Raman spectroscopy revealed that OVA-added GC-FB had the lowest hydrophobic interlinkages. Protein pattern analysis suggested that the OVA (1.58%) might contribute to the decrease in the myosin heavy chain (MHC) band intensity through cross-linked with MfP. These results suggested that EWP could improve the quality of GC-FBs and OVA played an important role with MfP gelation. This article is protected by copyright. All rights reserved.

Debittering effect of partially purified proteases from soybean seedlings on soybean protein isolate hydrolysate produced by alcalase

To explore the potential application of proteases from soybean seedlings in the debittering of soybean protein hydrolysates, soybean seeds were germinated from 1 to 10 days. It was found that the sixth day seedlings exhibited highest proteases activity (130 U/g). After partial purification, the activity of proteases (PSP) from the sixth day seedlings further increased to 2675 U/g. In addition, PSP exhibited maximum activity at 50 ℃ and pH 5.5, and mainly comprised of two proteins with the molecular weight of 64.57 and 25.12 kDa respectively. PSP could decrease the bitterness score of the soybean protein isolate hydrolysate (SPIH) produced by Alcalase 2.4L from 3.45 to 0 in 3 h. Meanwhile, the degree of hydrolysis of SPIH slightly increased from 11.87% to 15.61% without reducing the antioxidant activity. This study may provide a solution to the contradiction between removing the bitterness of soybean protein hydrolysates and maintaining the bioactivity.

Chemical and sensorial characterization of Tejate, a Mexican traditional maize-cocoa beverage, and improvement of its nutritional value by protein addition

Tejate is a Mexican traditional beverage elaborated with nixtamalized maize (Zea mays L.), cocoa (Theobroma cacao L.) beans, cacao flowers (Quararibea funebris), and mamey sapota fruit seeds (Pouteria sapota) that is considered a refreshing drink with satiety properties. Local formulations show a high content of minerals, but a relatively low protein content. The aim of this study was to identify a standardarized formulation but conserving physicochemical and sensorial ethnic identity of traditional Tejate, and to improve its nutritional value with the addition of protein without modifying its sensorial profile. A 2^4-1 fractional factorial design with central point was used to vary ingredients concentration and the amount of ash used for maize nixtamalization instead of lime (calcium hydroxide) was 75 g/100 g (w/w) of wood ashes in 2 L water. The standardized traditional formulation (TF) was selected through a sensory analysis with an expert panel: 20 g of cacao flowers, 30 g of mamey sapota fruit seeds, and 100 g of cocoa beans per kg of maize nixtamalized with 6% of ash. Whey protein concentrate (80% of protein) or soy protein isolate (88% of protein) were added to the TF at 1, 2, and 2.5%. The addition of 1% soy protein isolate increased TF protein content without modifying its physicochemical parameters, and improved the beverage stability during cold storage. The protein-rich Tejate formulation could be used as a functional beverage maintaining its ethnic identity.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13197-021-05073-w.

Fermented meat sausages and the challenge of their plant-based alternatives: A comparative review on aroma-related aspects

Traditional fermented meat sausages are produced around the world due to their convenience and sensory characteristics which are responsible for their high acceptability. They constitute a cultural heritage as shown by the high diversity of products around the world. Recent trends are addressing issues regarding innovation in their formulation by reduction of salt, fat and additives (curing salts). However, the current trend towards a reduction in the consumption of meat has produced an increase in the formulation of meat product analogues. This trend is the main focus of producers to offer new attractive products to consumers even though the aroma profile of traditional fermented meat sausages is not reached. In this manuscript, we review and discuss the chemistry of aroma formation in traditional fermented meat sausages in contrast to the potential of plant-based ingredients used in meat analogues.

Influence of Age and Individual Differences on Mouthfeel Perception of Whey Protein-Fortified Products: A Review

Protein needs are considered to increase with age, with protein consumption being associated with many positive outcomes. Protein-fortified products are often used to improve nutritional status and prevent age-related muscle mass loss in older adults. Accordingly, older adults are commonly provided with products fortified with whey protein; however, such products can cause mouthdrying, limiting consumption and product enjoyment. Currently, the extent to which age and individual differences (e.g., saliva, oral health, food oral processing) influence the perception of whey protein-derived mouthdrying is relatively unclear. Previous research in this area has mainly focused on investigating mouthdrying, without taking into account individual differences that could influence this perception within the target population. Therefore, the main focus of this review is to provide an overview of the relevant individual differences likely to influence mouthfeel perception (specifically mouthdrying) from whey protein-fortified products, thereby enabling the future design of such products to incorporate better the needs of older adults and improve their nutritional status. This review concludes that age and individual differences are likely to influence mouthdrying sensations from whey protein-fortified products. Future research should focus more on the target population and individual differences to maximise the benefits from whey protein fortification.

Fava bean (Vicia faba L.) for food applications: From seed to ingredient processing and its effect on functional properties, antinutritional factors, flavor, and color

The food industry, along with the consumers, is interested in plant-based diet because of its health benefits and environmental sustainability. Vicia faba L. (V. faba) is a promising source of pulse proteins for the human diet and can yield potential nutritional and functional ingredients, namely, flours, concentrates, and isolates, which are relevant for industrial food applications. Different processes produce and functionalize V. faba ingredients relevant for industrial food applications, along with various alternatives within each unit operation used in their production. Processing modifies functional properties of the ingredients, which can occur by (i) changing in overall nutritional composition after processing steps and/or (ii) modifying the structure and conformation of protein and of other components present in the ingredients. Furthermore, V. faba limitations due to off-flavor, color, and antinutritional factors are influenced by ingredient production and processing that play a significant role in their consumer acceptability in foods. This review attempts to elucidate the influence of different ways of processing on the functional, sensory, and safety aspects of V. faba L. ingredients, highlighting the need for further research to better understand how the food industry could improve their utilization in the market.

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.

Encapsulation of pea protein in an alginate matrix by cold set gelation method and use of the capsules in fruit juices

Plant-based proteins gained importance in recent years due to the increase in the awareness of healthy diet and in the consumption of plant-based foods. However, some features of plant-based proteins like the undesirable odor and flavor affect the sensorial properties of protein containing foods. Therefore, encapsulation of these proteins could be a good strategy to tackle with this problem. The objective of this study was to design microcapsules (beads) consisting of pea protein by using sodium alginate and to investigate the effect of different alginate concentrations (1.0, 1.5, and 2.0%) on the protein content, encapsulation efficiency, particle size, bead stability, and the morphology of the capsules and then add them to different fruit juices (pomegranate and melon) and examine the release behavior from the capsules. Rheological behavior of the juices including pectin were also investigated. TD- nuclear magnetic resonance relaxometry analysis through T₂ relaxation times was conducted on the capsules to observe the changes in the beads. In conclusion, alginate was found to be a suitable encapsulation coating for pea protein. Beads containing 1% alginate concentration was found to be the most effective with respect to protein content and bead stability. PRACTICAL APPLICATION: This study aims to design and characterize pea protein containing microcapsules capsules and their utilization in fruit juices. The study itself focused on a specific application on the fruit juices.

Molecular Functionality of Plant Proteins from Low- to High-Solid Systems with Ligand and Co-Solute

In the food industry, proteins are regarded as multifunctional systems whose bioactive hetero-polymeric properties are affected by physicochemical interactions with the surrounding components in formulations. Due to their nutritional value, plant proteins are increasingly considered by the new product developer to provide three-dimensional assemblies of required structure, texture, solubility and interfacial/bulk stability with physical, chemical or enzymatic treatment. This molecular flexibility allows them to form systems for the preservation of fresh food, retention of good nutrition and interaction with a range of microconstituents. While, animal- and milk-based proteins have been widely discussed in the literature, the role of plant proteins in the development of functional foods with enhanced nutritional profile and targeted physiological effects can be further explored. This review aims to look into the molecular functionality of plant proteins in relation to the transport of bioactive ingredients and interaction with other ligands and proteins. In doing so, it will consider preparations from low- to high-solids and the effect of structural transformation via gelation, phase separation and vitrification on protein functionality as a delivery vehicle or heterologous complex. Applications for the design of novel functional foods and nutraceuticals will also be discussed.

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.

Relevance of the Functional Properties of Enzymatic Plant Protein Hydrolysates in Food Systems

Proteins play a crucial role in determining texture and structure of many food products. Although some animal proteins (such as egg white) have excellent functional and organoleptic properties, unfortunately, they entail a higher production cost and environmental impact than plant proteins. It is rather unfortunate that plant protein functionality is often insufficient because of low solubility in aqueous media. Enzymatic hydrolysis strongly increases solubility of proteins and alters their functional properties. The latter is attributed to 3 major structural changes: a decrease in average molecular mass, a higher availability of hydrophobic regions, and the liberation of ionizable groups. We here review current knowledge on solubility, water- and fat-holding capacity, gelation, foaming, and emulsifying properties of plant protein hydrolysates and discuss how these properties are affected by controlled enzymatic hydrolysis. In many cases, research in this field has been limited to fairly simple set-ups where functionality has been assessed in model systems. To evolve toward a more widely applied industrial use of plant protein hydrolysates, a more thorough understanding of functional properties is required. The structure-function relationship of protein hydrolysates needs to be studied in depth. Finally, test model systems closer to real food processing conditions, and thus to real foods, would be helpful to evaluate whether plant protein hydrolysates could be a viable alternative for other functional protein sources.

Physicochemical and functional properties of beany flavour-free bambara groundnut protein isolate

BACKGROUND

Off-odour/flavour (beany) associated with bambara groundnut protein isolate (BGPI), due to oxidative degradation of lipids during either storage or processing, is a major problem limiting its application in foods. In this study, effects of heat treatment (50-80 °C) in combination with ethylenediaminetetraacetic acid (EDTA) on functional and sensory properties of BGPI were investigated.

RESULTS

BGPI prepared in the presence of EDTA had lower lipoxygenase and trypsin-inhibitory activities than BGPI prepared in the absence of EDTA, regardless of the heating temperature used (P < 0.05). Inactivation of lipoxygenase was associated with lowered peroxide value, thiobarbituric acid-reactive substances and beany odour/flavour intensity in BGPI stored at room temperature for 30 days. BGPI with heat treatment at temperatures lower than 70 °C had similar protein patterns to BGPI prepared by the typical process, except for the occurrence of proteins with molecular weight 70-82 kDa. BGPI with heat treatment showed decreased protein solubility but increased surface hydrophobicity and sulfhydryl group content. BGPI prepared in the presence of EDTA exhibited higher emulsion activity and stability indices as well as higher foam expansion and stability than BGPI prepared in the absence of EDTA, regardless of heating temperature (P < 0.05).

CONCLUSION

Heat treatment at 70 °C in the presence of 100 mmol L(-1) EDTA effectively reduced beany flavour development and enhanced the functionality of BGPI.

Structure and biotechnological applications of odorant-binding proteins

Odorant-binding proteins (OBPs) are small soluble polypeptides found in sensory organs of vertebrates and insects as well as in secretory glands and are dedicated to detection and release of chemical stimuli. OBPs of vertebrates belong to the family of lipocalin proteins, while those of insects are folded into α-helical domains. Both types of architectures are extremely stable to temperature, organic solvents and proteolytic digestion. These characteristics make OBPs suitable elements for fabricating biosensors to be used in the environment, as well as for other biotechnological applications. The affinity of OBPs for small volatile organic compounds is in the micromolar range, and they have broad specificity to a range of ligands. For biotechnological applications, OBPs can be expressed in bacterial systems at low cost and are easily purified. The large amount of information available on their structures and affinities to different molecules should allow the design of specific mutants with desired characteristics and represent a solid base for tailoring OBPs for different applications.