Slow Darkening Research Articles

Use of thermophysical properties to characterize cooking trends of slow- and regular-darkening pinto beans (Phaseolus vulgaris L.)

ABSTRACT This study investigated the thermophysical and cooking quality properties of both slow-darkening (SD) and regular-darkening (RD) pinto bean varieties, establishing genetic cooking variability in cooking traits and their interrelationships. The equilibrium moisture content (EMC) of the beans at 80, 90 and 100°C were determined. Thermal and physical properties were evaluated for both SD and RD pinto bean varieties at their respective EMC. Cooking quality properties, such as water absorption capacity and cooking time, were also assessed. Principal component and cluster analyses were used to establish interactive effects of the cooking-related traits to the cooking process. Bulk density and cooking time were significantly and negatively correlated (p < .05). The SD beans exhibited better cook characteristics compared to RD beans. Bulk density was the most influential trait during cluster formation. The findings highlight that physical and thermal properties play a critical role in the cooking process.

Seed yield improvements in slow‐darkening pinto bean: Registration of ‘ND Rodeo’

Abstract‘ND Rodeo’ (PVP no. 202300270; Reg. no. CV‐356, PI 703020) is a new slow‐darkening (SD) pinto bean (Phaseolus vulgaris L.) cultivar developed by the Dry Edible Bean Breeding Program at North Dakota State University and released by the North Dakota Agricultural Experiment Station. Pinto bean is the largest market class grown in the United States, representing over 47% of the total US production for dry beans, and more than 70% is produced in North Dakota. SD pinto beans offer a good alternative to commercial cultivars of regular darkening (RD) pinto beans, which are typically subject to the risk of economic losses due to seed coat darkening. However, reaching seed yields comparable to RD pintos has been challenging. Between 2017 and 2022, ND Rodeo was tested across 25 environments in North Dakota, where seed yield was significantly higher than the SD pinto cultivars ‘ND Palomino’ and ‘Vibrant’ (18% and 22%, respectively), and comparable with RD pinto cultivars ‘La Paz’ and ‘Monterrey’. ND Rodeo is resistant to Bean common mosaic virus and has intermediate resistance to common bacterial blight, but similar to the commercial checks, it is susceptible to local races/strains of white mold, anthracnose, and rust pathogens. ND Rodeo has an average height of 56 cm which is significantly higher than the average of ND Palomino, Vibrant, and La Paz, and exhibits a desirable upright architecture to facilitate direct harvest. It has a 100‐seed weight of 36.2 g and matures in 102 days. Canning quality was rated as acceptable.

Global analysis of common bean multidrug and toxic compound extrusion transporters (PvMATEs): PvMATE8 and pinto bean seed coat darkening.

In common bean (Phaseolus vulgaris L.), postharvest seed coat darkening is an undesirable trait that affects crop value. The increased accumulation of proanthocyanidins (PAs) in the seed coat results in darker seeds in many market classes of colored beans after harvest. The precursors of PAs are synthesized in the cytoplasm, and subsequently get glycosylated and then transported to the vacuoles where polymerization occurs. Thus, vacuolar transporters play an important role in the accumulation of PAs. Here, we report that common bean genome contains 59 multidrug and toxic compound extrusion genes (PvMATEs). Phylogenetic analysis of putative PvMATEs with functionally characterized MATEs from other plant species categorized them into substrate-specific clades. Our data demonstrate that a vacuolar transporter PvMATE8 is expressed at a higher level in the pinto bean cultivar CDC Pintium (regular darkening) compared to 1533-15 (slow darkening). PvMATE8 localizes in the vacuolar membrane and rescues the PA deficient (tt12) mutant phenotype in Arabidopsis thaliana. Analysis of PA monomers in transgenic seeds together with wild-type and mutants suggests a possible feedback regulation of PA biosynthesis and accumulation. Identification of PvMATE8 will help better understand the mechanism of PA accumulation in common bean.

Alternatives for selection of carioca common bean lines that combine upright plants and slow grain darkening

In Brazil, there is an increasing demand for common bean (Phaseolus vulgaris L.) cultivars having Carioca-type (cream-colored seed coat with brown stripes) beans which have a light color that persists for a longer time combined with the most possible upright plant architecture. However, plant breeders are finding it difficult to combine these two traits in the same cultivar. The aim of this study was to compare success in the selection of new common bean lines that combine the two traits in segregating populations with 25%, 50%, or 75% of the alleles from the parents contrasting in upright plant architecture or in bean grains with persistent light color. A biparental cross was performed between a parent with light-colored beans (P1) and another with upright plants (P2). Three populations were obtained from the F1 seeds, with allelic frequencies of 75%, 50%, and 25% of P1. Subsequently, progenies were evaluated in a similar number in each population in the F2:3, F2:4, F2:5, and F2:6 generations. The plant architecture (PA) and grain darkening (GD) traits were visually evaluated using a scoring scale. Genetic and phenotypic parameters were estimated for all generations. There was no expressive advantage in using populations with a greater allele proportion of the parent favorable to upright plant architecture or slow grain darkening either in releasing of variability or in the occurrence of progenies with favorable phenotypes for the two traits.

Investigations of the effects of the non‐darkening seed coat trait coded by the recessive jj alleles on agronomic, sensory, and cooking characteristics in pinto beans

AbstractThe beige background of the conventional pinto bean (Phaseolus vulgaris L.) seed coat turns brown over time due to oxidation of its proanthocyanidins. Pinto beans that have slow‐darkening (SD) or non‐darkening (ND) seed coats are more desired in the market because they are perceived to be fresh, high‐quality beans. However, correlations between the ND seed coat trait and agronomic performance have not been investigated. Therefore, the objectives of this study were to estimate variance components and broad‐sense heritabilities of agronomic and seed coat traits in pinto beans, and to determine if correlations exist between the ND seed coat trait and agronomic, sensory, and cooking traits in recombinant inbred lines, developed from crosses between ND pinto bean breeding lines, incorporating the ND gene from ‘Wit‐rood boontje’, with two regular‐darkening (RD) pinto bean varieties (‘Stampede’ in Population 1 and ‘La Paz’ in Population 2), grown in four different environments of southwest Ontario in 2016. Analysis of variance indicated significant differences between the RD and ND genotypes for grain yield, 100‐seed weight, hydration capacity, and the seed coat color parameters in both populations. The color parameter L*, which represents the whiteness of the seed coat, was selected as the main discriminative parameter between the RD and ND seed coat phenotypes. There was a weak positive genetic correlation between the ND trait and days to maturity in Population 1 (rg = .11). The ND trait showed weak negative genetic correlations with grain yield (rg = −.23 in Population 1 and rg = −.13 in Population 2). Moderately weak positive genetic correlations were found between the ND trait and hydration capacity in Population 1 (rg = .44) and Population 2 (rg = .40). The ND pinto beans were perceived as sweeter and had softer and smoother textures and shorter cooking times compared with the RD pinto beans.

Faster cooking times and improved iron bioavailability are associated with the down regulation of procyanidin synthesis in slow-darkening pinto beans (Phaseolus vulgaris L.)

Abstract Seed coat darkening after a delayed harvest or prolonged storage reduces the commercial value of dry beans and is caused by the oxidation of procyanidin compounds (condensed tannins). Slow-darkening (SD) pinto beans have a recessive gene (Psd), which alters procyanidin production – postponing their darkening over time. Procyanidins are important for the processing and nutrient bioavailability of beans, therefore, this study compared the postharvest cooking times and iron bioavailability of SD pinto varieties to regular-darkening (RD) pinto varieties. The results show SD pinto beans cook 30% faster and provide 2–7 times more bioavailable iron than RD pinto beans. No relationship between iron bioavailability, iron and phytate concentrations were detected among the pinto beans. However, lower procyanidin concentrations were strongly associated with faster cooking times and improved iron bioavailability of SD pinto beans. These findings indicate that the SD trait benefits the cooking quality and iron bioavailability of stored beans.

Selection of carioca common bean lines with slow darkening

Abstract The objective of this work was to evaluate the interaction between genotypes and environment for seed-coat darkening of common bean (Phaseolus vulgaris) seeds, in order to select lines that combine slow darkening, upright plants, resistance to lodging, and higher yield and 100-grain weight, with good adaptability and stability for these traits. Forty four pre-selected lines, originating from crosses between one cultivar with slow darkening and prostrate plants and four cultivars with normal darkening and upright plants, were evaluated in field trials conducted in 15 environments (combinations of locations, crop seasons, and years). Considering the mean values, adaptability, and stability for each isolated trait, most of the lines presented satisfactory performance: 75% for slow darkening, 48% for high yield, 59% for upright plants, 84% for resistance to lodging, and 68% for 100-grain weight. The effects of environments and of the genotype by environment interaction are important for the five studied traits. The CNFC 16754 and CNFC 16820 lines present slow seed-coat darkening, high yield and 100-grain weight, more upright plant architecture, and greater resistance to lodging, besides high adaptability and stability for these traits, which shows their potential for recommendation as new cultivars and confirms that it is possible to join desirable phenotypes for the five traits evaluated.

Postharvest seed coat darkening in pinto bean (Phaseolus vulgaris) is regulated by Psd , an allele of the basic helix-loop-helix transcription factor P.

Postharvest seed coat darkening in pinto bean is an undesirable trait that reduces the market value of the stored crop. Regular darkening (RD) pintos darken faster after harvest and accumulate higher level of proanthocyanidins (PAs) compared to slow darkening (SD) cultivars. Although the markers cosegregating with the SD trait have been known for some time, the SLOW DARKENING (Sd) gene identity had not been proven.Here, we identified Psd as a candidate for controlling the trait. Genetic complementation, transcript abundance, metabolite analysis, and inheritance study confirmed that Psd is the Sd gene. Psd is another allele of the P (Pigment) gene, whose loss-of-function alleles result in a white seed coat. Psd encodes a bHLH transcription factor with two transcript variants but only one is involved in PA biosynthesis. An additional glutamate residue in the activation domain, and/or an arginine to histidine substitution in the bHLH domain of the Psd-1 transcript in the SD cultivar is likely responsible for the reduced activity of this allele compared to the allele in a RD cultivar, leading to reduced PA accumulation.Overall, we demonstrate that a novel allele of P, Psd , is responsible for the SD phenotype, and describe the development of new, gene-specific, markers that could be utilized in breeding to resolve an economically important issue for bean producers.

Aging indicators for stored carioca beans

High temperature, moisture content and radiation conditions, common in the tropics, accelerate the physiological post-harvest disorders in beans, affect integument color and bean hardness. This study explored the darkening and hardening mechanisms in carioca type beans during storage. The contrasting genotypes for bean darkening and hardening (BRS Estilo and BRS Pontal: rapid darkening and hardening; BRSMG Madrepérola and CNFC 10467: slow darkening and partially resistant to hardening; and a Canadian genotype of the Pinto Bean type resistant to darkening (negative control)) were evaluated right after harvest and after six months storage at 20.3 ± 0.2 °C and 78.9 ± 6.0% RH, with respect to their physicochemical, biochemical and morphological attributes. All the samples hardened with time, but the velocity of darkening did not always parallel the degree of hardening of the beans (that increase linearly with time), which indicates that the color of the bean integument was not a safe indicator to predict the culinary quality of carioca beans. During storage, the SOD (superoxide dismutase) activity and LP (lipid peroxidation) in the cotyledon increased, and the increase was more significant in the integument of the rapid-darkening genotypes. The oxidative stress detected in the beans apparently started in the green bean formation phase, continuing during post-harvest, especially for the rapid-darkening beans. Quantification of the bivalent ions in the bean fractions, together with the degree of membrane damage was positively associated with bean darkening, independent of the group. Thus, aging of the carioca beans could be triggered by a complex mechanism involving diverse intrinsic factors in different degrees according to the genotype and the post-harvest period, but some parameters could serve as indicators, as cooking time, hardness and color, to differentiate between rapid and slow darkening beans.

Generation and validation of genetic markers for the selection of carioca dry bean genotypes with the slow-darkening seed coat trait

Slow darkening (SD) is a trait that helps to maintain a brighter seed coat appearance in certain market classes of dry beans. The aim of this study was to generate new fluorescence-based markers and validate previously identified microsatellite markers for linkage to the SD trait in lines of the carioca market class. Four segregating populations were generated by Embrapa, the Brazilian Agricultural Research Corporation, from crosses between the SD cultivar BRSMG Madrepérola and the regular-darkening cultivars BRS Estilo, BRS Cometa, BRS Notável and BRS Sublime. These populations were screened with the simple-sequence markers Pvsd-1158 and PVM02TC116 and with a TaqMan™ marker designed for the single-nucleotide polymorphism (SNP) PvbHLHp12804. A KASP marker was also designed for the PvbHLHp12804 marker for testing on advanced carioca lines developed by the University of Saskatchewan. In the carioca lines developed by Embrapa, PVM02TC116 proved unsuitable for marker-assisted selection (MAS). Both the Pvsd-1158 and PvbHLHp12804 markers were found to be tightly linked to the gene responsible for the SD trait, with genetic distances calculated at 2.8 cM for Pvsd-1158 and 2.0 and 3.1 cM for PvbbHLHp12804, respectively. These markers presented more than 97% of selection efficiency. The genotypic scoring using the PvbHLHp12804 KASP marker was perfectly correlated with the phenotype in all lines of the University of Saskatchewan. The results of this study validates the use of Pvsd-1158 as a gel-based marker for SD in carioca beans. The new fluorescence-based SNP PvbHLHp12804 markers exhibited very tight linkage to SD in carioca and pinto bean lines. These markers will be ideal for MAS for the SD trait in these market classes.

Carioca bean genotypes for tolerance to grain darkening by natural and accelerated methods

ABSTRACT The slow darkening of grains is sought by bean breeders because the consumers consider that darker grains demand more time for cooking. The analysis currently used takes around 90 days to differentiate grain color among genotypes. The objective was to evaluate the color as a function of the value of L* (lightness) of carioca beans, by natural and accelerated methods to verify equivalence between methods, validation of the methodology and identification of genotypes tolerant to the darkening. The grain darkening was compared and evaluated by natural darkening method under shelf conditions, in days storage, and accelerated darkening method under ultraviolet light, in hours. The natural darkening time of 90 days was statistically equal to 24 hours of accelerated darkening, and the difference among the genotypes could be obtained in a shorter time, indicating a correspondence in the methods. The accelerated darkening method can be used to shorten the analysis time in the routine of breeding programs.

Slow darkening of pinto bean seed coat is associated with significant metabolite and transcript differences related to proanthocyanidin biosynthesis

BackgroundPostharvest seed coat darkening in pinto bean is an undesirable trait resulting in a loss in the economic value of the crop. The extent of darkening varies between the bean cultivars and their storage conditions.ResultsMetabolite analysis revealed that the majority of flavonoids including proanthocyanidin monomer catechin accumulated at higher level in a regular darkening (RD) pinto line CDC Pintium than in a slow darkening (SD) line 1533–15. A transcriptome analysis was conducted to compare gene expression between CDC Pintium and 1533–15 and identify the gene (s) that may play a role in slow darkening processes in 1533–15 pinto.RNAseq against total RNA from RD and SD cultivars found several phenylpropanoid genes, metabolite transporter genes and genes involved in gene regulation or modification to be differentially expressed between CDC Pintium and 1533–15.ConclusionRNAseq analysis and metabolite data of seed coat tissue from CDC Pintium and 1533–15 revealed that the whole proanthocyanidin biosynthetic pathway was downregulated in 1533–15. Additionally, genes that encode for putative transporter proteins were also downregulated in 1533–15 suggesting both synthesis and accumulation of proanthocyanidin is reduced in SD pintos.

Combined selection in carioca beans for grain size, slow darkening and fast-cooking after storage times

Carioca bean presents grain darkening and increase in the cooking time in postharvest; this results in consumer rejection. The objective of this study was to select carioca bean genotypes with commercial grain size, slow darkening, and fast-cooking after storage. The completely randomized design was used in a 9 × 4 × 2 factorial arrangement, with three replications. Treatments consisted of nine common bean genotypes, four grain storage times (0, 2, 4 and 6 months), and two cultivation years (2014 and 2015). Carioca bean genotypes differed for mass of 100 grains, L, a* and b* values, water uptake, and cooking time; changes observed for these traits were not constant during storage and cultivation years. C 10-2-4/41 presents medium-sized beans (25.11 g), clearer color (L ≥ 55.00) with slightly red (a* ≤ 7.00) and slightly yellow (b* ≤ 16.00) shades, and fast-cooking (< 20 min) for fresh grains and grains stored for 6 months. The three superior carioca bean genotypes selected by the multiplicative index were C 10-2-4/41, Perola, and CNFC 11 948. C 10-2-4/41 presents commercial grain size, slow darkening and fast-cooking after 6 months of refrigerated storage and will be selected for the breeding program.

Simple Sequence Repeats Linked with Slow Darkening Trait in Pinto Bean Discovered by Single Nucleotide Polymorphism Assay and Whole Genome Sequencing

ABSTRACTSeed coat darkening in pinto bean (Phaseolus vulgaris L.) primarily occurs during prolonged storage and can result in significant loss in value based on it being a consumer perceived product flaw. Several slow darkening (SD) pintos, conditioned by the presence of the recessive sd gene, exist but are poorly adapted. Breeding for improved SD pintos is complicated by the recessive inheritance and expression of the trait in maternal tissue. We sought to develop capacity for marker‐assisted selection (MAS) for the SD trait. Three F2 populations (159 individuals) derived from crosses between SD parents, representing two different sources (1533‐15 and SDIP‐1) for the trait, and commercial regular darkening (RD) pintos were used to screen for single nucleotide polymorphisms (SNPs) linked with the sd locus. Separate DNA pools from SD and from RD F2 individuals genotyped for the sd locus were used to detect putative sd‐linked SNPs using the bulked‐segregant analysis strategy. Two of 1536 SNPs differentiated between the SD and RD DNA bulks for all three populations. The whole genome sequence scaffold possessing the two SNPs was canvassed for simple sequence repeats (SSRs). Three of 12 SSRs from the SNP region distinguished between the SD and RD lines. The three SSRs, Pvsd‐1157, Pvsd‐1158, and Pvsd‐0028, were observed to be tightly linked with the sd locus at 0.9, 0.4, and 3.1 cM, respectively, across the F2 populations. The SSRs assayed across a recombinant inbred line mapping population (CDC Pintium × 1533‐15) placed the sd gene on bean linkage group 7 between framework SSR markers BM210 and PvBR35. A survey of SD and RD advanced lines and cultivars revealed the SSRs will have utility for MAS of the SD trait in pinto bean and perhaps in other dry bean market classes as well.

Characterization of seed coat post harvest darkening in common bean (Phaseolus vulgaris L.)

Seed coat post harvest darkening (PHD) represents a problem for producers and consumers of several market classes of dry bean. There are three PHD phenotypes: (1) non-darkening (ND), (2) slow darkening (SD) and (3) regular darkening (RD). The inheritance of PHD was elucidated by evaluating populations derived from crosses among multiple RD, SD and ND genotypes. Results indicate that at least two unlinked major genes control the PHD trait in common bean. Recessive epistasis with three phenotypic classes explains the segregation ratios of populations from crosses between SD and ND parents. One gene, J, is responsible for whether a bean will darken as seeds from plants that are jj do not darken at all. Another gene, sd, influences how quickly a seed coat will darken with sdsd individuals darkening more slowly than those with the dominant Sd allele.

Self-darkening eyeglasses

TWO-FOR-ONE eyeglass lenses that darken when exposed to ultraviolet rays from the sun and return to their clear state indoors have come a long way since they were first invented in the 1960s. Early versions of these so-called photochromic lenses were plagued by slow darkening or lightening, and sometimes the lenses would get stuck midway. Newer models of the changeling spectacles are much quicker to activate and fade, and they come in both glass and lightweight plastic. The first photochromic lenses were made of glass and developed by scientists in the U.S. at Corning. The company has made improvements to its original process over the years, but in general, the science remains the same, says Lionel M. Tanguy, a glass application engineer at Corning Ophthalmic, in France. Glass photochromic lenses contain silver halide crystals embedded in a glass substrate. In the presence of UV-A light (wavelengths of 320–400 nm), electrons from the glass combine with ...

Slow Darkening in Pinto Bean (Phaseolus vulgaris L.) Seed Coats Is Controlled by a Single Major Gene

Postharvest seed coat darkening is a significant problem in pinto beans (Phaseolus vulgaris L.), resulting in product that is undesirable to consumers and that is discounted in the marketplace. There is a range in the rate and extent of darkening among pinto germplasm and recently, slow‐darkening (SD) lines have been identified. Line 1533‐15, an SD line from the University of Saskatchewan, was crossed to CDC Pintium, a regular darkening pinto, and seed of F1 and F2 individuals and F5:6 recombinant inbred lines were assessed for their darkening phenotype. Segregation data indicated that there is a single, recessive gene that controls the SD phenotype. All F2 individuals from a cross between 1533‐15 and Pinto Saltillo, another SD line, were slow‐darkening suggesting that the phenotype is controlled by the same gene in both lines. The simple genetics of this trait should facilitate the introduction of this trait into breeding programs, thereby increasing the quality of pinto beans being developed.

Performances of time–temperature indicators in the study of temperature exposure of packaged fresh foods

AbstractThe diffusion of time–temperature indicators (TTIs), attached as labels onto the packages of perishable food and non‐food products (intelligent packaging), is growing more and more. Aside from checking product shelf‐life, TTI devices can be used to monitor the distribution chain in real conditions. In this respect, the performances of some very common TTIs (A 12 Fresh Check, Lifelines Technologies) were extensively investigated in this work. The aim was to establish a procedure for an accurate, objective and reproducible estimate of the darkening progress of the sensitive area of the indicators and to discover a reliable data treatment to estimate the ‘effective temperature’, Teff, namely a fictitious average temperature that can replace the overall temperature fluctuations experienced by a packaged fresh food. The image analysis approach was found very useful for an accurate and sensitive definition of the information provided by the indicators, leading to the evidence of a very slow darkening of the sensitive region, even at −22°C. The kinetic parameterization of TTI responses was implemented in an EXCEL worksheet so as to directly evaluate Teff on the basis of a set of label brightness values acquired by image analysis. Comparing the calculated ‘effective temperature’ with the average temperature recorded with conventional devices, the reliability of the TTI tags and the accuracy of this procedure was demonstrated. Taking into account the low cost of the TTI tags, their wide usage can be suggested to monitor the various steps of the real distribution chain of a given product, namely, transport, bench and home storage. Copyright © 2001 John Wiley &amp; Sons, Ltd.