Insights into multiscale structure and digestive characteristic of starch from two cultivars of chestnut during kernel development.

Multiscale structure and digestive characteristic of starch during kernel development of Castanea henryi ('Jinzhui' (YS) and 'Baiyan No.1' (WS)) were investigated in this study. Structural analysis revealed that the surface of starch granules became smooth, the amylopectin content decreased (from 71.32 % to 70.47 %, from 71.44 % to 68.37 %, respectively), the chain length distribution of amylopectin reduced (the proportion of B1 chain decreased from 52.35 % to 50.60 %, from 52.22 % to 50.59 %, respectively) while the amorphous and semi-crystalline lamellae of starch increased during development, which was consistent with the decreasing relative crystallinity (from 28.79 % to 24.11 %, from 29.57 % to 23.66 %, respectively) and short-range ordering degree. The degradation of ordered structure further resulted in the increase of digestibility, especially in the late developmental stage, supported by a significant decrease of resistant starch content (from 70.21 % to 61.70 % and from 73.58 % to 58.86 %, respectively). Transcriptome analysis and RT-qPCR were performed to explore the possible molecular mechanisms affecting starch structure. The high expression of several key genes including AGPase, GBSS, SBE, SSS, ISA and PUL in late development stage might be the reason of structural changes during development. The results provided valuable information for starch accumulation during kernel development of Castanea henryi.

Infectivity responses of Salmonella enterica to bacteriophages on maize seeds and maize sprouts.

Salmonella enterica (S. enterica) is a major foodborne pathogen leading to a large number of outbreaks and bringing food safety concerns to sprouts. The control of S. enterica on maize sprouts is important because raw maize sprouts have been gaining attention as a novel superfood. Compared to conventional chemical methods, the applications of bacteriophages are regarded as natural and organic. This study investigated the effects of a 2 h phage cocktail (SF1 and SI1, MOI 1000) soaking on reducing the populations of three Salmonella enterica strains: S. Enteritidis S5-483, S. Typhimurium S5-536, and S. Agona PARC5 on maize seeds and during the storage of maize sprouts. The results showed that the phage cocktail treatment effectively reduced populations of S. enterica strains by 1-3 log CFU/g on maize seeds and decreased population of S. Agona PACR5 by 1.16 log CFU/g on maize sprouts from 7.55 log CFU/g at day 0 of the storage period. On the other hand, the upregulations of flagella gene pefA by 1.5-folds and membrane gene lpxA by 23-folds in S. Typhimurium S5-536 indicated a differential response to the phage cocktail treatment. Conversely, stress response genes ompR, rpoS, and recA, as well as the DNA repair gene yafD, were downregulated in S. Agona PARC5. This work shows the use of bacteriophages could contribute as a part of hurdle effect to reduce S. enterica populations and is beneficial to develop strategies for controlling foodborne pathogens in the production and storage of maize sprouts.

The impact of thermal pretreatment on phytochemical profiles and bioactivity of freeze-dried lily bulbs (Lilium lancifolium).

Lily bulbs are susceptible to deterioration during storage if improperly handled. To resolve this problem, it is necessary to investigate suitable processing techniques. The aim of this study is to evaluate the effects of steaming, blanching and microwave pretreatment on freeze-dried lily bulbs in terms of color, phenolic content and bioactivity. Results showed that appropriate steaming and blanching pretreatment could contribute to product characteristics similar to those of freeze-dried lily bulbs, with the maximum L* value reduced by only 7.57% and 0.55% respectively. Thermal pretreatment affected the retention, degradation and transformation of polyphenol, especially for regalosides. The polyphenol was closely associated with the browning of lily bulbs. Thermal processing caused the decline of regaloside A and the increase of regaloside B, which were the major phenolic monomers that can effectively inhibit the browning of lily bulbs. The antioxidant activity of freeze-dried lily pretreated with blanching for 6 min was the highest (4.39 ± 0.32 µmol TE/g DW), with an improvement of nearly 25.39% compared to that of untreated freeze-dried lily. Thus, the combination of freeze-dried with steaming or blanching pretreatment could be proposed as a sustainable strategy to improve the quality of lily bulbs for industrial application.

Modulation of carotenoid biosynthesis in maize (Zea mays L.) seedlings by exogenous abscisic acid and salicylic acid under low temperature.

KEY MESSAGE: Abscisic acid could regulate structural genes in the carotenoid biosynthesis pathway and alleviate the decrease of carotenoids in maize seedlings under low-temperature stress. Low temperature often hampers the development of maize seedlings and hinders the accumulation of carotenoids, which are functional against chilling stress for plants and providing health benefits for human. To explore effective approaches in reducing chilling stress and enhancing the potential nutritional values of maize seedlings, exogenous plant hormones abscisic acid (ABA) and salicylic acid (SA) that may affect carotenoid biosynthesis were applied on low-temperature-stressed maize seedlings. Results showed that low temperature significantly reduced the carotenoid levels in maize seedlings, only preserving 62.8% in comparison to the control. The applied ABA probably interacted with the ABA-responsive cis-acting elements (ABREs) in the promoter regions of PSY3, ZDS and CHYB and activated their expressions. Consequently, the total carotenoid concentration was apparently increased to 1121 ± 47 ng·g-1 fresh weight (FW), indicating the stress alleviation by ABA. The application of SA did not yield positive results in alleviating chilling stress in maize seedlings. However, neoxanthin content could be notably boosted to 52.12 ± 0.45 ng·g-1 FW by SA, offering a biofortification strategy for specific nutritional enhancement. Structural gene PSY1 demonstrated positive correlations with ß-carotene and zeaxanthin (r = 0.93 and 0.89), while CRTISO was correlated with total carotenoids (r = 0.92), indicating their critical roles in carotenoid accumulation. The present study exhibited the effectiveness of ABA to mitigate chilling stress and improve the potential nutritional values in low-temperature-stressed maize seedlings, thereby promoting the production of plant-based food sources.

Insights into tissue-specific anthocyanin accumulation in Japanese plum (Prunus salicina L.) fruits: A comparative study of three cultivars.

In the present study, three matured Japanese plum cultivars with different colored peel and flesh were selected to mine the key transcription factors regulating anthocyanin formation in tissues. Results showed that PsMYB10 was correlated with structural genes C4H, F3H, and ANS. PsMYB6 could positively regulate C4H (r = 0.732) and accumulated anthocyanins in Sanhua plum's flesh. Sanhua plum has the highest phenolic and anthocyanin contents (10.24 ± 0.37 gallic acid equivalent mg g-1 dry weight (DW) and 68.95 ± 1.03 µg g-1 DW), resulting itself superior biological activity as 367.1 ± 42.9 Trolox equivalent mg g-1 DW in oxygen radical absorbance capacity value and 72.79 ± 4.34 quercetin equivalent mg g-1 DW in cellular antioxidant activity value. The present work provides new insights into the regulatory mechanism of tissue-specific anthocyanin biosynthesis, confirming the pivotal role of anthocyanins in the biological activity of plums, providing essential support for the development of horticultural products enriched with anthocyanins.

Effect of thermal treatments on volatile profiles and fatty acid composition in sweet corn (Zea mays L.).

This study analyzed the effects of thermal processing on volatiles and fatty acids in sweet corn. There were 27 volatiles measured in fresh samples, and 33, 21, and 19 volatiles identified in the steaming, blanching, and roasting groups, respectively. Relative odor activity values (ROAVs) showed that characteristic aroma-active volatiles of sweet corn after thermal treatments included: (E)-2-nonenal, 1-octen-3-ol, beta-myrcene, dimethyl trisulfide, 1-(4,5-dihydro-2-thiazolyl)-ethanone, and d-limonene. Thermal treatments significantly increased the unsaturated fatty acids (oleic acid and linolenic acid) of sweet corn by 110 to 183% compared to fresh samples. Meanwhile, many characteristic volatiles were found that derived from the oxidative cleavage of fatty acids. The sweet corn aroma obtained by steaming for 5 min was considered the closest to fresh corn. Our research provided insight into aroma composition of different thermally processed sweet corn and laid the foundation for further exploring the sources of aroma compounds in thermally processed sweet corn.

Effect of Microwave Treatments Combined with Hot-Air Drying on Phytochemical Profiles and Antioxidant Activities in Lily Bulbs (Lilium lancifolium).

Lily bulbs (Lilium lancifolium Thunb.) are rich in phytochemicals and have many potential biological activities which could be deep-processed for food or medicine purposes. This study investigated the effects of microwaves combined with hot-air drying on phytochemical profiles and antioxidant activities in lily bulbs. The results showed that six characteristic phytochemicals were identified in lily bulbs. They also showed that with an increase in microwave power and treatment time, regaloside A, regaloside B, regaloside E, and chlorogenic acid increased dramatically in lily bulbs. The 900 W (2 min) and the 500 W (5 min) groups could significantly suppress the browning of lily bulbs, with total color difference values of 28.97 ± 4.05 and 28.58 ± 3.31, respectively, and increase the content of detected phytochemicals. The highest oxygen radical absorbance activity was found in the 500 W, 5 min group, a 1.6-fold increase as compared with the control (57.16 ± 1.07 µmol TE/g DW), which was significantly relevant to the group's phytochemical composition. Microwaves enhanced the phytochemicals and antioxidant capacity of lily bulbs, which could be an efficient and environmentally friendly strategy for improving the nutrition quality of lily bulbs during dehydration processing.

The Accumulation and Biosynthesis of Anthocyanin in Black, White, and Yellow Waxy Corns (Zea mays L. sinensis kulesh) during Kernel Maturation.

Waxy corn kernels with different colors have high phenolic content and good application potential in medicine and food healthcare. In our work, the content changes of phenolic and anthocyanins profiles were related to genes in the anthocyanin biosynthesis pathway, and the antioxidant activities of three different colors of waxy corn kernels (black, white, and yellow) were determined during kernel development. Results showed that growing temperature and light intensity could affect the accumulation of phytochemicals and antioxidant activities in waxy corns during maturation. Phenolic and antioxidant activities decreased over kernel maturation, and spring had higher nutrition levels during the best harvest time (20 and 25 days after pollination in the spring and autumn, respectively) for waxy corns. Cyanidin-3-O-glucoside and pelargonidin-3-O-glucoside were the main anthocyanins detected in the black waxy corns. The contents of cyanidin are higher than pelargonidin followed by peonidin in the autumn, while on the other hand, pelargonidin had a slightly higher content compared to cyanidin in the spring. DFR, CF1, and ANS were the key genes affecting anthocyanin accumulation. This work provided information on the best harvest time for the pigment of waxy corn in order to achieve relatively high phenolic profiles and antioxidant activities. It also illustrated the possible relationship between weather conditions, gene expression levels, and phenolic content during kernel development.

The modulation of light quality on carotenoid and tocochromanol biosynthesis in mung bean (Vigna radiata) sprouts.

This study aimed to identify the regulatory mechanisms of white, blue, red lights on carotenoid and tocochromanol biosynthesis in mung bean sprouts. Results showed that three lights stimulated the increase of the predominated lutein (3.2-8.1 folds) and violaxanthin (2.1-6.1 folds) in sprouts as compared with dark control, as well as ß-carotene (20-36 folds), with the best yield observed under white light. Light signals also promoted α- and γ-tocopherol accumulation (up to 1.8 folds) as compared with dark control. The CRTISO, LUT5 and DXS (1.24-6.34 folds) exhibited high expression levels under light quality conditions, resulting in an overaccumulation of carotenoids. The MPBQ-MT, TC and TMT were decisive genes in tocochromanol biosynthesis, and were expressed up to 4.19 folds as compared with control. Overall, the results could provide novel insights into light-mediated regulation and fortification of carotenoids and tocopherols, as well as guide future agricultural cultivation of mung bean sprouts.

l-Tryptophan synergistically increased carotenoid accumulation with blue light in maize (Zea mays L.) sprouts.

In the present study, l-tryptophan was applied in combination with blue light to modulate carotenoid biosynthesis in maize sprouts. The profiles of carotenoids, chlorophylls, and relative genes in carotenoid biosynthesis and light signaling pathways were studied. l-tryptophan and blue light both promoted the accumulation of carotenoids, and their combination further increased carotenoid content by 120%. l-tryptophan exerted auxin-like effects and stimulated PSY expression in blue light exposure maize sprouts, resulting in increased α- and ß- carotenes. l-tryptophan could also play a photoprotective role through the xanthophyll cycle under blue light. In addition, CRY in the light signaling pathway was critical for carotenoid biosynthesis. These findings provide new insights into the regulation of carotenoid biosynthesis and l-tryptophan could be used in conjunction with blue light to fortify carotenoids in maize sprouts.

Effect of light quality on polyphenol biosynthesis in three varieties of mung bean sprouts with different color seed coats.

KEY MESSAGE: We investigated the mechanism of the effect of different light qualities on the synthesis and regulation of mung bean sprouts. Light quality acts as a signal molecule, strongly enhancing polyphenol biosynthesis in sprouts. Mung bean (Vigna radiata) sprouts are a popular sprouting vegetable all over the world and are an excellent source of polyphenols with high antioxidant activity. This study investigated the effects of light qualities on the kinetic changes and metabolic regulation mechanism of light signal-mediating polyphenols in three mung bean sprout cultivars. Experimental results showed that three light qualities significantly enhanced the contents of caffeic acid, rutin, vitexin, genistin and delphinidin 3-glucoside. Interestingly, ferulic acid and vitexin responded selectively to blue light and red light, severally. Most genes involved in polyphenol biosynthesis were activated under different light quality conditions, resulting in an overaccumulation of phenylpropanoids. Pearson correlation analysis showed that PAL, F3H, F3'H and F3'5'H expression correlated highly with rutin, whereas ANS expression paralleled anthocyanin biosynthesis. Moreover, MYB111, MYB3, MYB4, MYB1 and MYC2 were critical regulators of polyphenol biosynthesis in mung bean sprouts. These changes were likely due to the changes in the expression of the photoreceptor genes CRY-D, PHOT2, PHYE and light response genes (PIF3 and HY5). Our results provide insights into polyphenol biosynthesis in sprouts and microgreens.

Effect of ultrasonic pretreatment on tocochromanol and carotenoid biofortification in maize (Zea mays L.) seedlings.

BACKGROUND: Maize is a sought-after food crop because it is micronutrient-rich and affordable. It is an excellent source of carotenoids and tocochromanols. To investigate ways to enhance the micronutrients in maize, we grew maize seedlings with ultrasonic pretreatment to study the effect of ultrasound pretreatment on the biofortification of tocochromanols and carotenoids using high-performance liquid chromatography and real-time quantitative polymerase chain reaction. RESULTS: Four tocopherol isomers, three tocotrienol isomers and six carotenoid components were measured in maize seedlings. Compared with the untreated maize seedlings, carotenoid content increased and reached the highest level at 8 min ultrasonic pretreatment (19.21 ± 0.44 µg g-1 fresh weight (FW)), but tocotrienol content evidently decreased. Tocopherol dropped at first but began to rise after 8 min ultrasonic pretreatment (258.1 ± 6.4 µg g-1 FW). In particular, zeaxanthin in maize seedlings doubled after pre-sonication, while lutein was boosted to 11.81 ± 0.20 µg g-1 FW. Ultrasonic pretreatment changed the predominant component of tocochromanols in maize seedlings from γ-tocotrienol to α-tocopherol, with the latter content being 1.3 times higher than in the untreated group. Up-regulation of key genes involved in the biosynthesis of tocopherols and carotenoids in maize seedlings occurred as a result of both 2 min and 6 min sonication pretreatment. In particular, Zm HPPD, Zm ZE, Zm ZDS and Zm MPBQ-MT could partly explain the changes in these phytochemicals. CONCLUSION: Wet ultrasonic pretreatment could increase tocopherol and carotenoid accumulation in maize seedlings but decrease tocotrienol synthesis. Some up-regulating genes are related to relevant syntheses, such as Zm HPPD, Zm ZE, Zm ZDS and Zm MPBQ-MT, which could influence the accumulation of tocopherols and carotenoids after ultrasonic pretreatment. © 2022 Society of Chemical Industry.

Comparative Assessment of Lignan, Tocopherol, Tocotrienol and Carotenoids in 40 Selected Varieties of Flaxseed (Linum usitatissimum L.).

Multiple varieties of flaxseeds have been identified in the world, yet the relationship between these varieties, their agronomic traits, and their seeds' quality remains unclear. This study aimed to determine the level of lignan, vitamins and carotenoids in 40 selected flaxseed varieties, and the relationship between varieties, agronomic traits, and seed quality was investigated. In this study, notably, fiber flax variety No. 225 exhibited the highest lignan content among all tested seeds. Additionally, oil variety No. 167 demonstrated the highest level of α-tocotrienol (α-T3), ß-tocopherol (ß-T), γ-tocotrienol (γ-T3), and ß-carotene (ß-Car.). Conversely, intermediate flax variety No. 16 displayed the highest content of α-tocopherol (α-T), but lowest content of lutein (Lut.), zeaxanthin (Zea.), ß-carotene (ß-Car.), and total carotenoids (Total Car.). Furthermore, a correlation was observed between petal color with the lignan, while a strong correlation has been explored in seed yield, seed type, plant natural height, and fiber content in straw. Nevertheless, further investigation is required to elucidate the internal relationship between varieties with compositions.

Characterization of Effects of Different Tea Harvesting Seasons on Quality Components, Color and Sensory Quality of "Yinghong 9" and "Huangyu" Large-Leaf-Variety Black Tea.

Harvesting seasons are crucial for the physicochemical qualities of large-leaf-variety black tea. To investigate the effect of harvesting seasons on physicochemical qualities, the color and sensory characteristics of black tea produced from "Yinghong 9" (Yh) and its mutant "Huangyu" (Hy) leaves were analyzed. The results demonstrated that Hy had better chemical qualities and sensory characteristics, on average, such as a higher content of tea polyphenols, free amino acids, caffeine, galloylated catechins (GaCs) and non-galloylated catechins (NGaCs), while the hue of the tea brew (ΔE*ab and Δb*) increased, which meant that the tea brew was yellower and redder. Moreover, the data showed that the physicochemical qualities of SpHy (Hy processed in spring) were superior to those of SuHy (Hy processed in summer) and AuHy (Hy processed in autumn), and 92.6% of the total variance in PCA score plots effectively explained the separation of the physicochemical qualities of Yh and Hy processed in different harvesting seasons. In summary, Hy processed in spring was superior in its physicochemical qualities. The current results will provide scientific guidance for the production of high-quality large-leaf-variety black tea in South China.

A genome-wide association study of folates in sweet corn kernels.

Folate is commonly synthesized in natural plants and is an essential water-soluble vitamin of great importance inhuman health. Although the key genes involved in folate biosynthesis and transformation pathways have been identified in plants, the genetic architecture of folate in sweet corn kernels remain largely unclear. In this study, an association panel of 295 inbred lines of sweet corn was constructed. Six folate derivatives were quantified in sweet corn kernels at 20 days after pollination and a total of 95 loci were identified for eight folate traits using a genome-wide association study. A peak GWAS signal revealed that natural variation in ZmFCL, encoding a 5-formyltetrahydrofolate cyclo-ligase, accounted for 30.12% of phenotypic variation in 5-FTHF content. Further analysis revealed that two adjacent SNPs on the second exon resulting in an AA-to-GG in the gene and an Asn-to-Gly change in the protein could be the causative variant influencing 5-FTHF content. Meanwhile, 5-FTHF content was negatively correlated with ZmFCL expression levels in the population. These results extend our knowledge regarding the genetic basis of folate and provide molecular markers for the optimization of folate levels in sweet corn kernels.

The modulation of light quality on carotenoids in maize (Zea mays L.) sprouts.

The present study aimed to identify the regulatory mechanisms of red, blue, and white light on carotenoid biosynthesis in maize sprouts. Determinations of carotenoid, chlorophyll and phytohormone profiles, as well as relative gene expression, were explored. The results identified enhancement of carotenoid and chlorophyll production as well as gene expression. Most notably, the expression levels of CRY, HY5, and beta-carotene 3-hydroxylase genes peaked under blue light. Photomorphogene-related hormone, auxins and strigolactone production was also altered under different lights and might have a role in carotenoid metabolism. Gibberellins competed with carotenoids for the precursor geranylgeranyl diphosphate and were hindered by certain light characteristics, probably via DELLA-PIF4 signalling. ERF021 and MYB68 were negative regulators of carotenoid biosynthesis in maize sprouts. These findings provide new insights into the light-regulated mechanism and biofortification of carotenoids in maize sprouts.

Effects of Naringin on Postharvest Storage Quality of Bean Sprouts.

This study investigated the effects of naringin on soybean and mung bean sprouts postharvest quality. It was found that naringin could maintain the appearance and quality of soybean sprouts and mung bean sprouts during a 6-day storage period as well as delay the occurrence of browning in mung bean sprouts and soybean sprouts. The optimal application rate of naringin was 50-100 µg/mL, which could effectively inhibit the activity of polyphenol oxidase (PPO) and peroxidase (POD) in bean sprouts and increase the ascorbic acid content, where this inhibition response to the browning of mung bean sprouts and soybean sprouts was significantly reduced. Naringin treatment increased gallic acid and p-coumaric acid content in mung bean sprouts as well as the daidzin and rutin content in soybean sprouts, which was also reflected in the improvement of antioxidant activity. The binding of naringin with PPO and POD was analyzed with molecular docking, naringin, and PPO had a lower binding energy (-1.09 Kcal/mol). In conclusion, naringin application in postharvest preservation of mung bean sprouts and soybean sprouts can maintain favorable consumer quality.

Effect of photoperiod on polyphenol biosynthesis and cellular antioxidant capacity in mung bean (Vigna radiata) sprouts.

This study investigated the effects of photoperiods on the metabolic regulation of polyphenol biosynthesis, as well as antioxidant activities in mung bean sprouts. Mung bean sprouts exposed to three different photoperiods: constant dark (light/dark, 0/24 h), semilight (light/dark, 12/12 h) and constant light (light/dark, 24/0 h). The results showed that the DFR, F6H, F3'5'H, F3'H, and F3H genes in the polyphenol biosynthetic pathway, as well as PHOT1/2, HY5, and MYBs, were strongly stimulated by photoperiods in sprouts. Seven polyphenol compounds (caffeic acid, rutin, vitexin, daidzin, glycitin, ferulic acid and p-coumaric acid) were detected in sprouts; the first five gradually increased with increasing illumination time, especially rutin, which showed a 547% increase. Illumination enhanced the antioxidant activities of sprouts, which was potentially related to the increases in caffeic acid, rutin and vitexin. These findings indicated that illumination would be a promising technique to improve the nutritional value of mung bean sprouts.