Alkaloid content and taste profile assessed by electronic tongue of Lupinus albus seeds debittered by different methods

Bitter flavors and bitter compounds in foods: identification, perception, and reduction techniques

Bitterness is one of the five basic tastes generally considered undesirable. The widespread presence of bitter compounds can negatively affect the palatability of foods. The classification and sensory evaluation of bitter compounds have been the focus in recent research. However, the rigorous identification of bitter tastes and further studies to effectively mask or remove them have not been thoroughly evaluated. The present paper focuses on identification of bitter compounds in foods, structural-based activation of bitter receptors, and strategies to reduce bitter compounds in foods. It also discusses the roles of metabolomics and virtual screening analysis in bitter taste. The identification of bitter compounds has seen greater success through metabolomics with multivariate statistical analysis compared to conventional chromatography, HPLC, LC-MS, and NMR techniques. However, to avoid false positives, sensory recognition should be combined. Bitter perception involves the structural activation of bitter taste receptors (TAS2Rs). Only 25 human TAS2Rs have been identified as responsible for recognizing numerous bitter compounds, showcasing their high structural diversity to bitter agonists. Thus, reducing bitterness can be achieved through several methods. Traditionally, the removal or degradation of bitter substances has been used for debittering, while the masking of bitterness presents a new effective approach to improving food flavor. Future research in food bitterness should focus on identifying unknown bitter compounds in food, elucidating the mechanisms of activation of different receptors, and developing debittering techniques based on the entire food matrix.

Flavor Chemical Research on Different Bee Pollen Varieties Using Fast E-Nose and E-Tongue Technology

Bee pollen, derived from various plant sources, is renowned for its nutritional and bioactive properties, aroma, and taste. This study examined the bee pollen with the highest yield in China obtained from four plant species, namely Brassica campestris (Bc), Nelumbo nucifera (Nn), Camellia japonica (Cj), and Fagopyrum esculentum (Fe), using fast e-nose and e-tongue technology to analyze their flavor chemistry. Results showed substantial differences in scent profiles among the varieties, with distinct odor compounds identified for each, including n-butanol, decanal, and ethanol, in Bc, Nn, and Cj, respectively. The primary odorants in Fe consist of E-2-hexen-1-ol and (Z)-3-hexen-1-ol. Additionally, e-tongue analysis revealed seven distinct tastes in bee pollen samples: AHS, PKS, CTS, NMS, CPS, ANS, and SCS, with variations in intensity across each taste. The study also found correlations between taste components and specific odor compounds, providing insights for enhancing product quality control in bee pollen processing.

The fate of quinolizidine alkaloids during the processing of lupins (Lupinus spp.) for human consumption

Lupin, a protein-rich grain legume, and products thereof, are becoming increasingly important in our diets. However, variable and high concentrations of quinolizidine alkaloids (QAs) may hamper this evolution. This study assessed the fate of QAs when processing Lupinus albus seeds and lupin-based foods, to give a first indication of the food industry's ability to sufficiently reduce the QA concentration. Typical unit processes, including toasting, dehulling, sterilization (sterilized jarred lupins), oven baking (cookies), frying (chips) and boiling in water (pasta), were simulated on lab-scale. A quantitative determination of five QAs and qualitative screening of other relevant QAs, in the derived fractions and lupin-based foods, was performed with a validated UHPLC-MS/MS and -HRMS method, respectively. Results revealed that the reduction in quinolizidine alkaloid content is highly dependent on the applied unit process, that QAs appear to be heat stabile, and that the depletion can be attributed to the leaching in cooking water.

Impacts of Different Processes on the Nutritional and Antinutritional Contents of White and Blue Lupin Seeds and Usage Possibilities for Sustainable Poultry Production

In the current era, it is important to consider economic and ecological sustainability issues while optimally meeting the nutrient needs of poultry. The use and research of alternative feedstuffs have gained importance due to these factors. The aim of this study is to reveal the raw lupin seeds' nutrient ingredients as an alternative feedstuff and the effects of debittering methods. In the present study, two different treatments (germination for 2 days; heat treatment in an autoclave at 130 °C for 20 min) were applied to white and blue lupin seeds, and the differences in nutrient compositions between them and raw seeds were determined. When fatty acid compositions were analyzed, oleic, γ-linolenic, arachidic, behenic, erucic, and lignoceric acid values were found to be the highest in the raw, autoclaved, and germinated forms of white lupin (p < 0.01). The highest values of palmitic, stearic, and linoleic acids were observed in blue lupin (p < 0.01). While the value of total quinolizidine alkaloids (QA) in raw white lupin grains was higher than 1.943 mg/g, it was higher than 1.800 mg/g in autoclaved and germination-treated grains. Similarly, the total QA value of raw blue lupin grains was 0.894 mg/g, 0.609 ± 0.244 mg/g in germination-treated seeds, and 0.705 ± 0.282 mg/g in autoclave-treated seeds. As a result of these findings, it can be said that the methods applied for the removal of bitterness gave promising results. Furthermore, it would be rewarding to use these lupin varieties in in vitro and in vivo experiments to reveal the impacts and mechanisms of debittering methods on poultry.

Lupin as a Source of Bioactive Antioxidant Compounds for Food Products

Four species of lupin (white lupin, yellow lupin, blue lupin and Andean lupin) are widely cropped thanks to the excellent nutritional composition of their seeds: high protein content (28-48 g/100 g); good lipid content (4.6-13.5 g/100 g, but up to 20.0 g/100 g in Andean lupin), especially unsaturated triacylglycerols; and richness in antioxidant compounds like carotenoids, tocols and phenolics. Particularly relevant is the amount of free phenolics, highly bioaccessible in the small intestine. However, the typical bitter and toxic alkaloids must be eliminated before lupin consumption, hindering its diffusion and affecting its nutritional value. This review summarises the results of recent research in lupin composition for the above-mentioned three classes of antioxidant compounds, both in non-debittered and debittered seeds. Additionally, the influence of technological processes to further increase their nutritional value as well as the effects of food manufacturing on antioxidant content were scrutinised. Lupin has been demonstrated to be an outstanding raw material source, superior to most crops and suitable for manufacturing foods with good antioxidant and nutritional properties. The bioaccessibility of lupin antioxidants after digestion of ready-to-eat products still emerges as a dearth in current research.

Isoflavone Content and Nutritional-Related Properties of Debittered Seeds from Two Andean Lupin (Lupinus mutabilis Sweet) Ecotypes Propagated in Two Soils

Lupinus mutabilis Sweet is a fabaceous plant native to the Andean highlands and produces seeds with valuable nutritional properties. Thus, as part of our research on native emerging food, the present study aimed at determining some nutritional and functional-related features of seeds from two L. mutabilis ecotypes after propagation in two different substrates commonly found in the Bogotá plateau. Propagated plants produced seeds that, after conventional debittering, exhibited attractive contents of soluble protein (24-39 g/100 g dry seed powder (dsp)), phenolic (787-1003 g/100 g dsp), isoflavone (1-104 g/100 g dsp), and iron (5.3-6.4 g/100 g dsp), as well as antioxidant capacity (39-78 µM/100 g dsp). Higher pH, humidity saturation, organic matter, and total nitrogen of silty loam soil promoted isoflavone accumulation and better antioxidant capacity at pH 4-7, and no soil effect was observed for total phenolic and iron contents. The profiles based on isoflavone aglycones were also recorded by liquid chromatography-mass spectrometry, detecting eleven main compounds with mutabilein as the most abundant isoflavone (38.3-104.3 g/100 g dsp). Finally, a formulation was developed to fabricate an emulsion-type drink based on the debittered, pulverized L. mutabilis seeds, resulting in different emulsifying capacities (19-100%) depending on the biopolymer stabilizer, being xanthan gum the best additive. The findings revealed an attractive Andean lupin profile to be used as a raw food material.

Chemical Characterization of White Lupin (Lupinus albus) Flour Treated by Extrusion Cooking and Aqueous Debittering Processes

Lupin is a very nutritious legume with high levels of protein and fiber, but it also contains quinolizidine alkaloids which, depending on the species, can accumulate to toxic levels. The objective of this work was to evaluate the white lupin chemical composition, due to the effects of different processes (aqueous debittering, extrusion cooking, and reactive extrusion), aiming at reducing total alkaloids, preserving fibers, and increasing in vitro protein digestibility. Regarding raw material, the aqueous process reduced significantly total alkaloids (-93.87%), increased dietary fiber (+22.03%), and increased protein digestibility (+6.73%), whereas the extrusion processes were inefficient to reduce alkaloids (< -3.70%) and reduced the dietary fiber content, the reduction being more severe during reactive extrusion (-75.36%). Protein digestibility was improved by extrusion cooking (+3.07%), while the reactive extrusion reduced digestibility (-12.50%). Electrophoresis and quantification of soluble proteins and aromatic amino acids confirmed the high digestibility index, staying only the γ-conglutin fraction in the digested samples evaluated by SDS-PAGE. The aqueous process proved to be the best option, as it reduces the alkaloid content to safe levels and improves the protein digestion of white lupin flour.

Effect of Debittering with Different Solvents and Ultrasound on Carotenoids, Tocopherols, and Phenolics of Lupinus albus Seeds

Lupin seeds represent a rich nutritional source of bioactive compounds, including antioxidant molecules such as carotenoids, tocopherols, and phenolics. However, before consumption, the lupin seeds must be debittered in order to remove their bitter and toxic alkaloids. This study analyzed the impact on the bioactive compounds of Lupinus albus seeds of a recent time- and water-saving debittering method, which employs alternative washing solutions (0.5% or 1% of either NaCl or citric acid), with or without the assistance of ultrasound. The results were compared with those of two control methods using water or a NaCl solution. The sonication, when it was significant, led to a large loss of bioactive compounds, which was most likely due to its extraction capability. The seeds that were debittered without ultrasound presented high concentrations of tocopherols (172.8-241.3 mg/kg DM), carotenoids (10.9-25.1 mg/kg DM), and soluble-free (106.9-361.1 mg/kg DM), soluble-conjugated (93.9-118.9 mg/kg DM), and insoluble-bound (59.2-156.7 mg/kg DM) phenolics. The soluble-free fraction showed the greatest loss after a prolonged treatment. Overall, debittering with citric acid or NaCl preserved the highest concentration of antioxidant compounds by shortening the treatment time, thus preventing extensive leaching.

Free Phenolic Compounds, Antioxidant Capacity and FT-NIR Survey of Debittered Lupinus mutabilis Seeds

Lupinus mutabilis protein-rich seeds must be debittered before consumption. The aim of this research was to assess free phenolic compounds, antioxidant capacity and FT-NIR spectra of flours from debittered seeds of 33 Andean ecotypes of L. mutabilis, and five varieties belonging to L. luteus, L. angustifolius and L. albus, as controls. The free phenolics were quantified by RP-HPLC, while the antioxidant capacity was evaluated spectrophotometrically through the Reducing Power, ABTS, FRAP and DPPH methods. The free phenolics of L. mutabilis were mostly (85.5–99.6%) flavonoids (genistein and genistein derivatives, apigenin, catechin and naringenin). Other compounds, detected in low quantities, were phenylethanoids (tyrosol and tyrosol derivative) and phenolic acids (cinnamic acid derivatives). The highest total free phenolic concentration was observed in H6 INIA BP (1393.32 mg/kg DM), followed by Chacas, Moteado beige, Huánuco and Lircay. The antioxidant capacity of the L. mutabilis ecotypes exceeded that of the controls and was correlated to flavonoids content. Additionally, a relationship between free phenolic compounds and spectral bands was established by FT-NIR, paving the way for a fast, reliable and non-destructive approach to lupin seeds characterisation. Even after debittering, lupin flours maintained high free phenolic concentrations and antioxidant capacity.