The MdCBF1/2-MdTST1/2 module regulates sugar accumulation in response to low temperature in apple.

Soluble sugar content is a key component in controlling fruit flavor, and its accumulation in fruit is largely determined by sugar metabolism and transportation. When the diurnal temperature range is greater, the fleshy fruits accumulated more soluble sugars and become more sweeter. However, the molecular mechanism underlying this response remains largely unknown. In this study, we verified that low-temperature treatment promoted soluble sugar accumulation in apple fruit and found that this was due to the upregulation of the Tonoplast Sugar Transporter genes MdTST1/2. A combined strategy using assay for transposase-accessible chromatin (ATAC) sequencing and gene expression and cis-acting elements analyses, we identified two C-repeat Binding Factors, MdCBF1 and MdCBF2, that were induced by low temperature and that might be upstream transcription factors of MdTST1/2. Further studies established that MdCBF1/2 could bind to the promoters of MdTST1/2 and activate their expression. Overexpression of MdCBF1 or MdCBF2 in apple calli and fruit significantly upregulated MdTST1/2 expression and increased the concentrations of glucose, fructose, and sucrose. Suppression of MdTST1 and/or MdTST2 in an MdCBF1/2-overexpression background abolished the positive effect of MdCBF1/2 on sugar accumulation. In addition, simultaneous silencing of MdCBF1/2 downregulated MdTST1/2 expression and apple fruits failed to accumulate more sugars under low-temperature conditions, indicating that MdCBF1/2-mediated sugar accumulation was dependent on MdTST1/2 expression. Hence, we concluded that the MdCBF1/2-MdTST1/2 module is crucial for sugar accumulation in apples in response to low temperatures. Our findings provide mechanistic components coordinating the relationship between low temperature and sugar accumulation as well as new avenues to improve fruit quality.

Expression of a single-chain monellin (MNEI) mutant with enhanced stability in transgenic mice milk.

Monellin is a sweet protein that may be used as a safe and healthy sweetener. However, due to its low stability, the application of monellin is currently very limited. Here, we describe a wild-type, a double-sites mutant (E2N/E23A) and a triple-sites mutant (N14A/E23Q/S76Y) of single-chain monellin (MNEI) expressed in transgenic mice milk. Based on enzyme-linked immunoassay (ELISA), Western blot, and sweetness intensity testing, their sweetness and stability were compared. After boiling for 2 min at different pH conditions (2.5, 5.1, 6.8, and 8.2), N14A/E23Q/S76Y-MNEI showed significantly higher sweetness and stability than the wild-type and E2N/E23A-MNEI. These results suggest that N14A/E23Q/S76Y-MNEI shows remarkable potential as a sweetener in the future.

Fruit sugar hub: gene regulatory network associated with soluble solids content (SSC) in Prunus persica.

Chilean peach growers have achieved worldwide recognition for their high-quality fruit products. Among the main factors influencing peach fruit quality, sweetness is pivotal for maintaining the market's competitiveness. Numerous studies have been conducted in different peach-segregating populations to unravel SSC regulation. However, different cultivars may also have distinct genetic conformation, and other factors, such as environmental conditions, can significantly impact SSC. Using a transcriptomic approach with a gene co-expression network analysis, we aimed to identify the regulatory mechanism that controls the sugar accumulation process in an 'O × N' peach population. This population was previously studied through genomic analysis, associating LG5 with the genetic control of the SSC trait. The results obtained in this study allowed us to identify 91 differentially expressed genes located on chromosome 5 of the peach genome as putative new regulators of sugar accumulation in peach, together with a regulatory network that involves genes directly associated with sugar transport (PpSWEET15), cellulose biosynthesis (PpCSLG2), flavonoid biosynthesis (PpPAL1), pectin modifications (PpPG, PpPL and PpPMEi), expansins (PpEXPA1 and PpEXPA8) and several transcription factors (PpC3H67, PpHB7, PpRVE1 and PpCBF4) involved with the SSC phenotype. These results contribute to a better understanding of the genetic control of the SSC trait for future breeding programs in peaches.

Sweet and sour sips: No effect of repeated exposure to sweet or sour-tasting sugary drinks on children's sweetness preference and liking.

Health agencies advocate reducing children's sweetness exposure to lower sweetness preference or liking to ultimately lower sugar intake. However, the relationship between sweetness exposure, preference, and liking remains unclear. This work investigated the influence of exposure to a sucrose-containing sweet or sour-tasting drink on sweetness preference and liking for sweet and sour products in 4-7-year-old children (n = 65). The children were randomized into three groups with one daily exposure to either the sweet drink, sour drink, or water (control group) for 14 days. Sweetness preference was assessed at baseline (t1), day 15 (t2), and two months after the intervention (t3), using a forced-choice, paired comparison test with five beverages varying in sweetness intensity. Hedonic liking for the intervention drinks, a sweet and sour yogurt, and a sweet and sour candy was evaluated using a 5-point pictorial scale. Linear mixed models revealed a significant increase in sweetness preference from t1 to t3 (F(2) = 7.46, p < 0.001). However, ANCOVA analysis indicated that this effect was not caused by the intervention. Based on linear mixed models, we observed that children's hedonic liking for sweet and sour products remained stable from t1 to t3 and was not influenced by the intervention. These findings suggest that 14 exposures to a sucrose-containing sweet or sour-tasting drink did not affect sweetness preference or liking in 4-7-year-old children.

Reducing sweetness expectation in milk tea by crossmodal visuo-auditory interaction.

In the realm of healthy dietary choices about reducing sweetness perception, the exploration of crossmodal effects stands as a frequently employed approach. Both music and color can independently influence flavor evaluation and gustatory experience by eliciting emotions. However, less research has been done on the effects of audio-visual crossmodal interactions on sweetness expectations and perceptions. The present study conducted two experiments delving into the crossmodal effect on sweetness expectation and perception of milk tea by manipulating the emotional valence of music and packaging color. The results showed that positive (vs. negative) music led to higher sweetness expectations and perceptions for milk teas with neutral packaging color. Irrespective of music, participants had higher sweetness expectations for milk tea with positive or neutral (vs. negative) packaging colors. The congruence of valence between music and packaging color influenced sweetness perception. Positive (vs. negative) music correlated with a sweeter perception when the packaging color was positive. Exposed to negative music, subjects showed a higher sweetness perception with negative (vs. positive) packaging colors. In conclusion, the results suggest that the valence of music and packaging color crossmodally influence consumers' evaluation of milk tea, and it differs depending on whether it was tasted. Thus, this study has demonstrated the crossmodal influence of music and packaging color, providing valuable implications for healthy eating and marketing applications.

Integrating Computational and Experimental Methods to Identify Novel Sweet Peptides from Egg and Soy Proteins.

Sweetness in food delivers a delightful sensory experience, underscoring the crucial role of sweeteners in the food industry. However, the widespread use of sweeteners has sparked health concerns. This underscores the importance of developing and screening natural, health-conscious sweeteners. Our study represents a groundbreaking venture into the discovery of such sweeteners derived from egg and soy proteins. Employing virtual hydrolysis as a novel technique, our research entailed a comprehensive screening process that evaluated biological activity, solubility, and toxicity of the derived compounds. We harnessed cutting-edge machine learning methodologies, specifically the latest graph neural network models, for predicting the sweetness of molecules. Subsequent refinements were made through molecular docking screenings and molecular dynamics simulations. This meticulous research approach culminated in the identification of three promising sweet peptides: DCY(Asp-Cys-Tyr), GGR(Gly-Gly-Arg), and IGR(Ile-Gly-Arg). Their binding affinity with T1R2/T1R3 was lower than -15 kcal/mol. Using an electronic tongue, we verified the taste profiles of these peptides, with IGR emerging as the most favorable in terms of taste with a sweetness value of 19.29 and bitterness value of 1.71. This study not only reveals the potential of these natural peptides as healthier alternatives to traditional sweeteners in food applications but also demonstrates the successful synergy of computational predictions and experimental validations in the realm of flavor science.

Identification and Validation of Key Genes Related to Preferred Flavour Profiles in Australian Commercial Papaya (Carica papaya L.).

Commercial papaya varieties grown in Australia vary greatly in taste and aroma. Previous profiling has identified undesirable 'off tastes' in existing varieties, discouraging a portion of the population from consuming papayas. Our focus on enhancing preferred flavours led to an exploration of the genetic mechanisms and biosynthesis pathways that underlie these desired taste profiles. To identify genes associated with consumer-preferred flavours, we conducted whole RNA sequencing and de novo genome assembly on papaya varieties RB1 (known for its sweet flavour and floral aroma) and 1B (less favoured due to its bitter taste and musty aroma) at both ripe and unripe stages. In total, 180,368 transcripts were generated, and 118 transcripts related to flavours were differentially expressed between the two varieties at the ripe stage. Five genes (cpBGH3B, cpPFP, cpSUS, cpGES and cpLIS) were validated through qPCR and significantly differentially expressed. These genes are suggested to play key roles in sucrose metabolism and aromatic compound production pathways, holding promise for future selective breeding strategies. Further exploration will involve assessing their potential across broader germplasm and various growth environments.

The T1R3 subunit of the sweet taste receptor is activated by D2O in transmembrane domain-dependent manner.

Deuterium oxide (D2O) is water in which the heavier and rare isotope deuterium replaces both hydrogens. We have previously shown that D2O has a distinctly sweet taste, mediated by the T1R2/T1R3 sweet taste receptor. Here, we explore the effect of heavy water on T1R2 and T1R3 subunits. We show that D2O activates T1R3-transfected HEK293T cells similarly to T1R2/T1R3-transfected cells. The response to glucose dissolved in D2O is higher than in water. Mutations of phenylalanine at position 7305.40 in the transmembrane domain of T1R3 to alanine, leucine, or tyrosine impair or diminish activation by D2O, suggesting a critical role for T1R3 TMD domain in relaying the heavy water signal.

Sensitivity of human sweet taste receptor subunits T1R2 and T1R3 to activation by glucose enantiomers.

We have previously shown that l-glucose, the non-caloric enantiomer of d-glucose, activates the human sweet taste receptor T1R2/T1R3 transiently expressed in HEK293T cells. Here, we show that d- and l-glucose can also activate T1R2 and T1R3 expressed without the counterpart monomer. Serine mutation to alanine in residue 147 in the binding site of T1R3 VFT domain, completely abolishes T1R3S147A activation by either l- or d-glucose, while T1R2/T1R3S147A responds in the same way as T1R2 expressed without its counterpart. We further show that the original T1R2 reference sequence (NM_152232.1) is less sensitive by almost an order of magnitude than the reference sequence at the time this study was performed (NM_152232.4). We find that out of the four differing positions, it is the R317G in the VFT domain of T1R2, that is responsible for this effect in vitro. It is significant for both practical assay sensitivity and because glycine is found in this position in ~20% of the world population. While the effects of the mutations and the partial transfections were similar for d and l enantiomers, their dose-response curves remained distinct, with l-glucose reaching an early plateau.

Study protocol of the sweet tooth study, randomized controlled trial with partial food provision on the effect of low, regular and high dietary sweetness exposure on sweetness preferences in Dutch adults.

BACKGROUND: Several health organizations recommend lowering the consumption of sweet-tasting foods. The rationale behind this recommendation is that a lower exposure to sweet foods may reduce preferences for sweet tasting foods, thus lowering sugar and energy intake, and in turn aiding in obesity prevention. However, empirical data supporting this narrative are lacking. In fact, relatively little is known about the contribution of long-term sweet taste exposure on one's sweetness preferences. METHODS: The primary objective of this randomized controlled trial is to assess the effect of low, regular and high dietary sweetness exposure on preference for sweet foods and beverages, and to compare these effects between intervention groups. One hundred and eighty adults aged 18-65 years with a BMI of 18.5-30.0 kg/m2 will be recruited and randomly allocated to either: low dietary sweetness exposure (LSE) (10-15% daily energy from sweet tasting foods), regular dietary sweetness exposure (RSE) (25-30% daily energy from sweet tasting foods), or high dietary sweetness exposure (HSE) (40-45% daily energy from sweet tasting foods), for 6 months, followed by a 4-month follow up. Intervention foods are provided ad libitum, covering approximately 50% of the daily number of food items, to include sugar-sweetened, low-calorie-sweetener-sweetened and non-sweet foods. The primary outcome measure is the difference in change in sweetness preference from baseline to 6 months between intervention groups. Secondary outcomes include: change in sweet taste preferences at different time-points; taste intensity perception; behavioral outcomes: food choice and intake, sweet-liker type, food cravings, dietary taste preferences and dietary taste patterns; anthropometric outcomes: body composition, waist-hip circumference, body weight; and biochemical outcomes: glucose variability and biomarkers related to CVD and diabetes. DISCUSSION: This study will generate important data on the effect of dietary sweetness exposure on sweetness preferences in terms of effect size and change, duration of change and its impact on food intake, body weight status and associated health outcomes. TRIAL REGISTRATION: The study protocol has been registered on ClinicalTrials.gov (ID no. NCT04497974, Registered 4 August 2020, https://clinicaltrials.gov/ct2/show/NCT04497974 ) and approved by Wageningen's Medical Ethical Committee (ABR no. NL72134).

Impact of acute consumption of beverages containing plant-based or alternative sweetener blends on postprandial appetite, food intake, metabolism, and gastro-intestinal symptoms: Results of the SWEET beverages trial.

Project SWEET examined the barriers and facilitators to the use of non-nutritive sweeteners and sweetness enhancers (hereafter "S&SE") alongside potential risks/benefits for health and sustainability. The Beverages trial was a double-blind multi-centre, randomised crossover trial within SWEET evaluating the acute impact of three S&SE blends (plant-based and alternatives) vs. a sucrose control on glycaemic response, food intake, appetite sensations and safety after a carbohydrate-rich breakfast meal. The blends were: mogroside V and stevia RebM; stevia RebA and thaumatin; and sucralose and acesulfame-potassium (ace-K). At each 4 h visit, 60 healthy volunteers (53% male; all with overweight/obesity) consumed a 330 mL beverage with either an S&SE blend (0 kJ) or 8% sucrose (26 g, 442 kJ), shortly followed by a standardised breakfast (∼2600 or 1800 kJ with 77 or 51 g carbohydrates, depending on sex). All blends reduced the 2-h incremental area-under-the-curve (iAUC) for blood insulin (p < 0.001 in mixed-effects models), while the stevia RebA and sucralose blends reduced the glucose iAUC (p < 0.05) compared with sucrose. Post-prandial levels of triglycerides plus hepatic transaminases did not differ across conditions (p > 0.05 for all). Compared with sucrose, there was a 3% increase in LDL-cholesterol after stevia RebA-thaumatin (p < 0.001 in adjusted models); and a 2% decrease in HDL-cholesterol after sucralose-ace-K (p < 0.01). There was an impact of blend on fullness and desire to eat ratings (both p < 0.05) and sucralose-acesulfame K induced higher prospective intake vs sucrose (p < 0.001 in adjusted models), but changes were of a small magnitude and did not translate into energy intake differences over the next 24 h. Gastro-intestinal symptoms for all beverages were mostly mild. In general, responses to a carbohydrate-rich meal following consumption of S&SE blends with stevia or sucralose were similar to sucrose.

Feasibility and acceptability of miracle fruit application prior to the consumption of sour-tasting foods as a weight-loss strategy in adults with diabetes or prediabetes: A randomized crossover trial.

Miracle fruit (MF) has emerged as a promising option for healthy noncaloric sweeteners due to its sour-to-sweet taste-modifying effects and high antioxidant activity. We aimed to examine the feasibility and acceptability of using MF as a weight-loss strategy for individuals with diabetes or prediabetes. Fifty Korean-American men and women (25 participants each) aged 45-75 years with diabetes or prediabetes were recruited in this study. They participated in a randomized placebo-controlled crossover trial where they took the assigned tablet (either an MF tablet or a placebo-sugar candy) 10 min before consuming food. Using a 9-point hedonic scale, participants assessed the likings of overall, flavor, texture, and aftertaste for green apples, goat cheese, lemonade, pickles, and plain fat-free yogurt before and 10 min after taking the assigned tablet. Additionally, overall liking for meals and calorie intake were assessed during subsequent ad libitum meal sessions. An ANOVA for a crossover design, and independent and paired t-tests were used to compare the outcomes. The results revealed that all postintervention liking values for sour-tasting foods were higher than the respective preintervention liking values for both interventions. However, the MF intervention showed significantly higher pre-post differences in liking for all sour-tasting foods and the overall liking values for breakfast and dinner compared to the placebo intervention (P < 0.001). Furthermore, the MF intervention resulted in a significantly lower calorie intake for each meal than the placebo (P < 0.001). These findings suggest that MF intervention can be considered a viable weight-loss strategy for individuals with diabetes.

Effects of aroma-taste interaction on the sensory attributes of rebaudiosides in soymilk and milk.

BACKGROUND: Rebaudioside A (Reb-A) and rebaudioside M (Reb-M) are intense natural sweeteners but can also elicit bitterness and a bitter aftertaste. In this study, the effect of vanilla and chocolate flavorings on the sensory attributes of Reb-A and Reb-M applied to soymilk and milk was investigated to identify whether the addition of flavoring could enhance the sweetness via aroma-taste interactions. RESULTS: Nine samples each of soymilk and milk were formulated by adding sucrose, Reb-A and Reb-M in three flavor conditions (no flavoring, vanilla, and chocolate). Descriptive analyses were conducted using nine panelists for the soymilk and eight panelists for the milk. Another descriptive analysis was conducted using the same samples with olfactory occlusion via the wearing of a nose clip to check whether the sweetness enhancement was due to olfactory input. The chocolate flavoring significantly enhanced the sweetness of Reb-A and Reb-M and reduced the bitterness, bitter aftertaste and astringency in both soymilk and milk. The vanilla flavoring was not as effective as the chocolate flavoring in enhancing sweetness. When the olfactory passage was closed with a nose clip, the sweetness enhancement and bitterness suppression were not detected in the samples. CONCLUSION: The addition of chocolate flavoring could successfully improve the sensory profile of soymilk sweetened with Reb-A through aroma-taste interactions. © 2023 Society of Chemical Industry.

Enhancement effect of odor and multi-sensory superposition on sweetness.

The impact of sugary foods on public health has contributed to the development of low-sugar and sugar-substituted products, and sugar reduction has become a major challenge for the food industry. There is growing empirical evidence that odor can enhance the perception of sweetness without increasing the caloric load. This current review summarizes the researches on odor-induced sweetness enhancement published in recent years and discusses the mechanisms and influencing factors of odor-sweetness interactions. In addition, by combing existing studies, this paper also summarizes the research methods and strategies to investigate odor-induced sweetness enhancement. Finally, the feasibility of synergistic enhancement of sweetness through the superposition of odor with other senses (texture, visual, etc.) is also discussed and analyzed. In conclusion, odor-induced sweetness enhancement may present an alternative or complementary approach for developing foods with less sugar.

The sweet tooth of infancy: Is sweetness exposure related to sweetness liking in infants up to 12 months of age?

Infants become increasingly exposed to sweet-tasting foods in their first year of life. However, it is still unclear whether repeated exposure to sweet taste is linked to infants' sweetness liking during this period. Making use of data from the OPALINE cohort, this study aimed to examine the link between sweetness exposure and sweetness liking during two important periods in early infant feeding: at the start of complementary feeding (3-6 months) and the transition to the family table (10-12 months). Infants' sweetness exposure was assessed using 7-d food records which were completed by mothers every month (n 312), reporting daily consumption rates of formula/breast milk or complementary food and the type of formula milk and/or complementary foods for each feeding occasion. Infants' sweetness liking was studied in the laboratory at 3, 6 and 12 months of age by assessing their response to a lactose-water solution and the amount drunk of this solution compared with plain water. Linear regressions and structural equation model assessed associations between exposure to and liking for sweetness at 6 and 12 months. Neither at 6 (n 182) nor at 12 months (n 197) was sweetness exposure associated with sweetness liking. While sweetness liking at 3 months was unrelated to liking at 6 months, the latter predicted sweetness liking at 12 months. These findings demonstrate no association between sweetness exposure at 3 to 12 months and liking at 6 and 12 months despite a sharp increase in sweetness exposure in that period. However, sweetness liking at 6 and 12 months was positively associated.

Biochemical, Sensory, and Molecular Evaluation of Flavour and Consumer Acceptability in Australian Papaya (Carica papaya L.) Varieties.

Inconsistency in flavour is one of the major challenges to the Australian papaya industry. However, objectively measurable standards of the compound profiles that provide preferable taste and aroma, together with consumer acceptability, have not been set. In this study, three red-flesh papayas (i.e., 'RB1', 'RB4', and 'Skybury') and two yellow-flesh papayas (i.e., '1B' and 'H13') were presented to a trained sensory panel and a consumer panel to assess sensory profiles and liking. The papaya samples were also examined for sugar components, total soluble solids, and 14 selected volatile compounds. Additionally, the expression patterns of 10 genes related to sweetness and volatile metabolism were assessed. In general, red papaya varieties had higher sugar content and tasted sweeter than yellow varieties, while yellow varieties had higher concentrations of citrus floral aroma volatiles and higher aroma intensity. Higher concentrations of glucose, linalool oxide, and terpinolene were significantly associated with decreased consumer liking. Significant differences were observed in the expression profiles of all the genes assessed among the selected papaya varieties. Of these, cpGPT2 and cpBGLU31 were positively correlated to glucose production and were expressed significantly higher in '1B' than in 'RB1' or 'Skybury'. These findings will assist in the strategic selective breeding for papaya to better match consumer and, hence, market demand.

Sweetness profiles of glycosyl rebaudioside A and binary mixtures with sugar alcohols in aqueous solution and a lemonade model system.

BACKGROUND: The demands for better-tasting alternative sweeteners have driven efforts to improve the sensory properties of rebaudioside A (Reb-A), such as glycosylation and blending with bulk sweeteners. This study attempted to (i) investigate the sensory profiles of a novel sweetener, glycosyl rebaudioside A (gReb-A), and its 1:1 mixtures with erythritol or maltitol, and (ii) compare between the sensory characteristics in an aqueous solution and lemonade. RESULTS: The concentrations of the sweeteners were prepared to match the sweetness intensity of a 7% (w/v) sucrose solution using relative sweetness values determined using the two-alternative forced-choice test. Eight trained panelists identified sensory profiles of the sweeteners in an aqueous solution and lemonade using a descriptive analysis protocol. gReb-A had significantly less bitterness and lingering sweetness than Reb-A did, eliciting a sensory profile similar to that of sucrose. The mixture of gReb-A and erythritol was not sensorially differentiated from the sucrose in the aqueous solution. Blending with maltitol significantly enhanced the sweetness and suppressed the bitterness of gReb-A. gReb-A and its binary mixtures were perceived as more similar to sucrose in the lemonade than in solution. CONCLUSION: This study suggests that glycosylation and blending with erythritol and maltitol gave a more sucrose-like sweetness profile in the aqueous solution and lemonade. The results of the study can be used to develop adequate sugar substitutes for acidic beverages. © 2021 Society of Chemical Industry.

The neuroscience of sugars in taste, gut-reward, feeding circuits, and obesity.

Throughout the animal kingdom sucrose is one of the most palatable and preferred tastants. From an evolutionary perspective, this is not surprising as it is a primary source of energy. However, its overconsumption can result in obesity and an associated cornucopia of maladies, including type 2 diabetes and cardiovascular disease. Here we describe three physiological levels of processing sucrose that are involved in the decision to ingest it: the tongue, gut, and brain. The first section describes the peripheral cellular and molecular mechanisms of sweet taste identification that project to higher brain centers. We argue that stimulation of the tongue with sucrose triggers the formation of three distinct pathways that convey sensory attributes about its quality, palatability, and intensity that results in a perception of sweet taste. We also discuss the coding of sucrose throughout the gustatory pathway. The second section reviews how sucrose, and other palatable foods, interact with the gut-brain axis either through the hepatoportal system and/or vagal pathways in a manner that encodes both the rewarding and of nutritional value of foods. The third section reviews the homeostatic, hedonic, and aversive brain circuits involved in the control of food intake. Finally, we discuss evidence that overconsumption of sugars (or high fat diets) blunts taste perception, the post-ingestive nutritional reward value, and the circuits that control feeding in a manner that can lead to the development of obesity.

Transcriptomic and Metabolic Profiling of High-Temperature Treated Storage Roots Reveals the Mechanism of Saccharification in Sweetpotato (Ipomoea batatas (L.) Lam.).

The saccharification of sweetpotato storage roots is a common phenomenon in the cooking process, which determines the edible quality of table use sweetpotato. In the present study, two high saccharified sweetpotato cultivars (Y25, Z13) and one low saccharified cultivar (X27) in two growth periods (S1, S2) were selected as materials to reveal the molecular mechanism of sweetpotato saccharification treated at high temperature by transcriptome sequencing and non-targeted metabolome determination. The results showed that the comprehensive taste score, sweetness, maltose content and starch change of X27 after steaming were significantly lower than those of Y25 and Z13. Through transcriptome sequencing analysis, 1918 and 1520 differentially expressed genes were obtained in the two periods of S1 and S2, respectively. Some saccharification-related transcription factors including MYB families, WRKY families, bHLH families and inhibitors were screened. Metabolic analysis showed that 162 differentially abundant metabolites related to carbohydrate metabolism were significantly enriched in starch and sucrose capitalization pathways. The correlation analysis between transcriptome and metabolome confirmed that the starch and sucrose metabolic pathways were significantly co-annotated, indicating that it is a vitally important metabolic pathway in the process of sweetpotato saccharification. The data obtained in this study can provide valuable resources for follow-up research on sweetpotato saccharification and will provide new insights and theoretical basis for table use sweetpotato breeding in the future.

Influence of Prebiotic Fructans on Retronasal Aroma from Elderly Individuals.

This study investigates for the first time the role of fructans with prebiotic effects (oligofructose and inulin) on retronasal aroma among elderly individuals. The impact of oligofructose (20% w/w) on retronasal aroma release was investigated using proton transfer reaction-mass spectrometry (PTR-MS) after 73 elderly individuals consumed aqueous solutions aromatized with five aroma compounds (pentan-2-one, nonan-2-one, hexan-2,3-dione, octanal and linalool). The influence of oligofructose and inulin (10% w/w) on the perceived intensity (n = 26) of two aroma descriptors (butter and floral) was also studied together with the possibility of a dumping effect on aroma evaluation due to the sweetness provided by the fructans. The results showed that the presence of oligofructose produced a significant reduction in retronasal aroma release, which could be generally explained by the physicochemical properties of aroma compounds. The presence of prebiotic fructans did not significantly affect the perceived intensity of butter and floral notes, although a dumping effect for the butter descriptor in the presence of oligofructose was observed. To conclude, these findings suggest that although fructans can exert an impact on retronasal aroma, they can be used at precise concentrations to increase the prebiotic fibre content of food products without affecting the aroma profile of foods.