HMF Formation during Heat-treatment of Milk-type Products as Related to Milkfat Content

Homogenized lactose/caseinate model systems and milk with different fat content were heated at 110 to 150 °C for up to 30 min. Free and total hydroxymethylfurfural (HMF) were measured by reverse-phase high-performance liquid chromatography. Multifactor analysis of variance was applied to determine whether milkfat content contributed to free and total HMF formation. There was a negative effect of milkfat on the formation of total HMF in both systems. However, free HMF formation was promoted by higher milkfat content in milk, but not in the lactose-caseinate model. Milkfat affected also the free and total HMF formation in commercial pasteurized milk, ultra heat-treated milk, and bottle-sterilized milk.     

Effect of antibrowning agents on browning and intermediate formation in the glucose-glutamic acid model

In this study, the inhibitory effects of antibrowning agents on browning and the formation of intermediates such as 3-deoxyglucosone (3-DG) and hydroxymethylfurfural (HMF) were evaluated with a glucose-glutamic acid model for soybean paste. The initial antibrowning capacity was measured in the following order: pentasodium tripolyphosphate < citric acid and oxalic acid < cysteine and glutathione < sodium sulfite. Our data showed that antibrowning agents, such as pentasodium tripolyphosphate, citric acid, and oxalic acid, were maintained antibrowning capacities during storage at both 4 and 30 °C, respectively. However, both cysteine and glutathione was reduced with storage time, especially in the air. A marked effect of nitrogen treatment was noted for 3 of the antibrowning agents after storage in air at 30 °C in the following order: sodium sulfite < cysteine < glutathione. The formation ratio of 3-DG and HMF was higher after storage at 30 °C than at 4 °C. These compounds were produced most abundantly in the presence of sodium sulfite, and the yields were not related significantly to the degree of browning. Citric acid and oxalic acid were identified as the most effective in inhibitors of browning and intermediates, even during storage in air at 30 °C.     

微波辅助蔗糖制备5-羟甲基糠醛

研究了在微波辐射下以蔗糖为原料制备羟甲基糠醛的反应,考察了不同温度、催化剂浓度、底物浓度和反应时间对5-羟甲基糠醛收率的影响。较优的反应条件为:微波功率600 W,温度433.15 K,硫酸浓度0.15mol/L,蔗糖质量分数12%,反应时间6 min,羟甲基糠醛的收率和选择性分别为32.4%和36.2%。     

Effect of storage on the bioactive compounds and antioxidant activity of quince nectar

The changes of bioactive components and antioxidant activity of quince nectar were determined during 9 months of storage at 5, 20, 30 and 40 °C. The amount of total phenolics, flavonoids and antioxidant activity was significantly declined during storage at all temperatures. Loss of L‐ascorbic acid at 5, 20, 30 and 40 °C was 32.08%, 43.69%, 65.21% and 88.82%, respectively. L‐ascorbic acid degradation was in accordance with the first‐order reaction kinetics, and activation energy was found as 43.65 kJ mol^?1. After 9 months of storage, Hydroxymethylfurfural (HMF) contents of quince nectars were 15.01, 16.64, 21.69 and 57.89 mg kg^?1 at 5, 20, 30 and 40 °C, respectively. HMF accumulation fitted a zero‐order kinetic model, and activation energy was found as 88.30 kJ mol^?1. A significant correlation was found among L‐ascorbic acid, total phenolics, flavonoids and antioxidant activity.     

Catalytic dehydration of glucose to 5‐hydroxymethylfurfural with a bifunctional metal‐organic framework

Glucose conversion to 5‐hydroxymethylfurfural (HMF) generally undergoes catalytic isomerization reaction by Lewis acids followed by the catalytical dehydration to HMF with Brönsted acid. In this work, a sulfonic acid functionalized metal‐organic framework MIL‐101(Cr)‐SO₃H containing both Lewis acid and Brönsted acid sites, was examined as the catalyst for γ‐valerolactone‐mediated cascade reaction of glucose dehydration into HMF. Under the optimal reaction conditions, the batch heterogeneous reaction gave a HMF yield of 44.9% and selectivity of 45.8%. Reaction kinetics suggested that the glucose isomerization in GVL with 10 wt % water follows the second‐order kinetics with an apparent activation energy of 100.9 kJ mol^?1. Continuous reaction in the fixed‐bed reactor showed that the catalyst is highly stable and able to provide a steady HMF yield. This work presents a sustainable and green process for catalytic dehydration of biomass‐derived carbohydrate to HMF with a bifunctional metal‐organic framework. © 2016 American Institute of Chemical Engineers AIChE J, 62: 4403–4417, 2016     

Second-generation bioethanol of hydrothermally pretreated stover biomass from maize genotypes

Twelve maize genotypes, were agronomically evaluated and their stover hydrothermally pretreated in a temperature range of 210–225 °C to assess the effects of genotype and pretreatment severity on stover recalcitrance toward bioethanol conversion. Maize genotypes exhibited significant variation for biomass yield and all agronomic evaluated, while among all cell wall constituents measured in the unpretreated stover, only ash content showed differences among genotypes. The pretreatment severities assayed impacted most stover compositional traits, and the glucose recovered after enzymatic hydrolysis displayed a similar profile among genotypes with similar genetic background. Harsher pretreatment conditions maximized the potential cellulosic bioethanol production (208–239 L/t), while the mildest maximized the bioethanol from the hemicellulosic hydrolysates (137–175 L/t). Consequently, when both pentose and hexose sugars were considered, the total potential bioethanol produced at the lowest and highest pretreatment temperatures was similar in all genotypes (292–358 L/t), indicating that the lowest temperature (210 °C) was the optimal among all assayed. Importantly, the ranking of genotypes for bioethanol yield (L/ha) closely resembled the ranking for stover yield (t/ha), indicating that breeding for biomass yield would increase the bioethanol production per hectare regardless of the manufacturing process. Similarly, the genetic regulation of corn stover moisture is possible and relevant for efficient energy production as biomass moisture has a potential impact on stover transportation, storage and processing requirements. Overall, these results indicate that local landrace populations are important genetic resources to improve cultivated crops, and that simultaneous breeding for production of grain and stover bioethanol is possible in corn.     

六水合三氯化铬催化蔗糖脱水合成5-羟甲基糠醛

研究了用CrCl3·6H2O催化蔗糖脱水转化为5-羟甲基糠醛（HMF）的反应,考察了蔗糖浓度、催化剂用量、反应温度和反应时间对产率的影响。利用紫外分光光度法测定产物并计算产率。较佳反应条件为：蔗糖浓度0．3mol／L、催化剂用量（以蔗糖质量计）3％、反应温度160℃、反应时间30min,在此条件下,产物收率可达55．3％。     

An ionic liquid reaction and separation process for production of hydroxymethylfurfural from sugars

Hydroxymethylfurfural (HMF) is viewed as a potential platform material to make a variety of chemicals and products out of renewable resources. In this work, a complete ionic liquid reaction and separation process is presented for nearly stoichiometric conversion of fructose into HMF. The silicalite adsorbent material is demonstrated for separation of 99% pure HMF out of ionic liquid reaction mixtures through a packed column and for recovery of the unconverted sugars and reaction intermediates along with the ionic liquid. Membrane‐coated silicalite particles are prepared and studied for a practical adsorption process with separation performances comparable to or better than the powder material. It is discovered that nearly all the fresh fructose feed could be converted into HMF with the recycled ionic liquid under suitable reaction conditions. These research results lead to a new HMF production process much simpler than the current paraxylene manufacturing process from petroleum oil. © 2013 American Institute of Chemical Engineers AIChE J, 60: 300–314, 2014