Production of aroma compounds by Geotrichum candidum on waste bread crumb

After selection from eight yeast commercial or type strains based on their aromatic potential to valorize bread by-products, Geotrichum candidum ATCC 62217 formed fruity aroma compounds (pineapple-like) on fermented waste bread (35% white bread crumb and 65% water). Fatty acids esters were identified, including ethyl esters of acetic acid, propionic acid, butyric acid and isobutyric acid. Their production corresponded to the stationary growth phase of the strain and, after 48 h, it was improved by agitation and, to a lesser extent, at 30°C compared to 25 or 20°C. Aromatic properties of the strain were linked to its ability to metabolize organic acids.     

Water vapor transport properties during staling of bread crumb and crust as affected by heating rate

In order to develop a mathematical model to simulate mass transfer occurring between the crumb and the crust during bread staling, water vapor sorption properties, i.e., moisture diffusivity, WVP and sorption of bread crumb and crust were investigated at 15 °C. Two types of bread baked with two heating rates (7.39 °C/min and 6.32 °C/min) were considered. Sorption and desorption isotherms were determined using Dynamic Vapor Sorption (DVS) and FF and GAB models were applied in the range of 0–0.95 a_w, to fit isotherm curves. Diffusivity was determined from sorption isotherms by using Fick's law and WVP was measured by two methods (gravimetric and from sorption data). Results exhibited maximum values of D_eff in the range of 0.1 and 0.14 g/g d.b. moisture contents. They varied between 0.88 × 10^? 10 and 0.92 × 10^? 10 m²/s for the crust and between 2.24 × 10^? 10 and 2.64 × 10^? 10 m²/s for the crumb, baked respectively at 220 °C and 240 °C. Results of WVP showed that the crust baked at 240 °C was significantly more permeable than the crust baked at 220 °C. This fact was attributed to the difference in porosity and the molecular structure due to heating effects. Also, the presence of steam in the oven atmosphere enhanced the development of higher porosity in the crust, leading to different structures and properties. Moreover, SEM images showed that starch granules were intact and less swelled in the upper crust when baking at 240 °C, resulting in higher WVP.     

Modification of appetite by bread consumption: A systematic review of randomized controlled trials

The inclusion of different ingredients or the use of different baking technologies may modify the satiety response to bread, and aid in the control of food intake. The aim of this study was to perform a systematic search of randomized clinical trials on the effect of bread consumption on appetite ratings in humans. The search equation was (“Bread”[MeSH]) AND (“Satiation”[MeSH] OR “Satiety response”[MeSH]), and the filter “clinical trials.” As a result of this procedure, 37 publications were selected. The satiety response was considered as the primary outcome. The studies were classified as follows: breads differing in their flour composition, breads differing in ingredients other than flours, breads with added organic acids, or breads made using different baking technologies. In addition, we have revised the data related to the influence of bread on glycemic index, insulinemic index and postprandial gastrointestinal hormones responses. The inclusion of appropriate ingredients such as fiber, proteins, legumes, seaweeds and acids into breads and the use of specific technologies may result in the development of healthier breads that increase satiety and satiation, which may aid in the control of weight gain and benefit postprandial glycemia. However, more well-designed randomized control trials are required to reach final conclusions.     

Characterizing the cellular structure of bread crumb and crust as affected by heating rate using X-ray microtomography

The effect of two baking conditions 240 °C and 220 °C (corresponding to heating rates 7.39 and 6.11 °C/min respectively) on the cellular structure of bread was investigated using X-ray microtomography. A comparison between helium pycnometry and X-ray microtomography was carried out and confirmed the quality of analysis in 3-D. Porosity profiles were determined in the interface crust/crumb and showed higher porosity and lower density of the upper crust when increasing heating rate and baking with steaming. The porosity profile of the whole slice bread showed differences between breads baked at 220 °C and 240 °C; that can be explained by the non uniformity in local expansion during baking resulting in different areas of variable density. Higher density was found in the bottom of the slice due to compression forces during baking. However, the upper zone of the slice was more porous, in relation with the expansion. These differences influence the texture and led to different kinetics of staling. Results of tortuosity confirm that the relative path length is shorter along the height related to the expansion of the bread during baking. Additionally, the relative path length through the pores is shorter when baking at 240 °C than when baking at 220 °C, in relation with porosity.     

Effect of long-term consumption of various krill products on lysosomal proteinase activity in rats

Total and nonsedimentable cathepsin A, B, C and D activity was studied in the liver and kidneys, as well as in the blood serum of rats fed with rations containing protein isolate from krill (100 and 50%) and krill flesh (100%) during .6 and 12 months. Selective activation of cathepsins A dn D in the liver, intensified nonsedimentable activity of all lysosomal proteinases studied, most manifest at the initial stages of the experiment (4 months), and a sharp (0.5-3.5-fold) rise of these enzymes' activity in the blood serum were recorded in rats when the krill isolate served the only source of protein (100%) in their ration.     

Effects of dietary consumption of cranberry powder on metabolic parameters in growing rats fed high fructose diets

The effect of dietary consumption of a cranberry powder (CP) containing increased amounts of procyanidins and other phytochemicals on metabolic parameters associated with metabolic syndrome was investigated in growing rats fed a high fructose diet. Dietary treatments were control (starch based), high fructose (HF), and HF containing either 3.3, 6.6, or 33 g CP/kg diet. Fasting plasma glucose and triglycerides tended to be higher with HF feeding and were reduced by feeding CP. The area under curve following an oral glucose tolerance test was 35-50% higher in animals fed HF diet vs. control and was decreased to control levels by the low or medium but not high CP diet. Feeding CP tended to lower fasting plasma insulin. Homeostatic models of insulin resistance (HOMA-IR) and β-cell function (HOMA-BCF) were lowest in animals fed low or medium CP diets (p < 0.05). Rats fed the control starch diet had slightly higher food intake, final body weight, and abdominal fat compared to animals fed other diets. Kidney weight was higher in HF group and feeding CP decreased kidney weight to normal levels. In the fed state, plasma triglyceride was increased with HF diet, whereas insulin was lower in animals fed HF diet. Overall, inclusion of CP in the diet was effective in modulating some aspects of metabolic parameters associated with metabolic syndrome and the medium level of CP in the diet produced a better response than the lower and higher CP levels.     

Glutathione-related enzymic activities in rats receiving high cholesterol or standard diets supplemented with two forms of selenium

Selenium deficiency was produced in rats fed a high cholesterol diet for 57 days (Group 1). It was characterized by an increase in malondialdehyde (MDA) an end product of lipid peroxidation and by the dramatic collapse of selenium-dependent glutathione peroxidase activity (GSHPx) in plasma, erythrocytes and in homogenate supernatant fraction of liver, kidney and heart compared with rats fed a standard diet containing sodium selenite (Group 3). A compensatory rise in the activity of liver glutathione S-transferase (GST) activity and also in glutathione reductase (GSSGR) activity was accompanied by an increase in NADPH-generating enzymes glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase. Adequate dietary selenium supplementation by Se-rich Spirulina corrected all the selenium deficiency effects (Group 2), then, GSHPx and NADPH-consuming enzymes activities were of the same magnitude as those exhibited by rats fed a standard diet containing adequate selenium in the form of sodium selenite. Based on this study, it is concluded that Se-enriched Spirulina behave as an excellent selenium carrier.     

Antioxidant phenolic compounds of pomegranate wines produced by different maceration methods

Various methods were evaluated in the production of ‘Hicaz’ pomegranate wine by microvinification. The chemical, phenolic and antioxidant characteristics of the wines were assessed by measurement of water‐soluble dry matter, acidity, density, alcohol content, volatile acidity, total monomeric anthocyanins, polarized colour intensity and individual phenolic compounds. Three different methods – classical maceration (N), seed‐supplemented maceration (S) and seed + enzyme supplemented maceration (E) – were applied. Total phenolic compounds of pomegranate must and wines (after 18 months of storage) were 1897 mg/L (must), 1663 mg/L (N), 1339 mg/L (E) and 1414 mg/L (S). Phenolic compounds in pomegranate must and wines included gallic acid, vanillic acid, caffeic acid, ferulic acid, p‐coumaric acid, hydroxycinnamic acid, epicatechin and catechin. Total antioxidant capacities (Trolox equivalents) of pomegranate must and wines (N, E and S) were 9.9 mm /L (must), 9.8 mm /L (N), 9.7 mm /L (E) and 9.5 mm /L (S). Copyright © 2017 The Institute of Brewing & Distilling     

长期饮用白酒中度扰动肠道微生物多样性演替研究

为探究饮酒对肠道微生物多样性特征及形成演替的影响机制,通过4个月的监控,调查了长期饮酒组和空白对照组各20人的肠道常见菌属-粪杆菌属（Faecalibacterium）、拟杆菌属（Bacteroides）、罗氏菌属（Roseburia）、双歧杆菌属（Bifidobacterium）和布劳特氏菌属（Blautia）的特征。结果表明,长期酒精摄入可以产生肠道菌群的中度扰动,引起较强的微生物种群的随机生长响应,并伴随着强烈的微生物种内和种间竞争随机过程、基质的生产和消耗随机过程,它们有效地减弱了各个微生物种群波动的自相关性和互相关性,肠道菌群多样性降低且有紊乱的趋势;非长期饮酒者肠道微生物群落中的各菌种数量呈现异步趋同波动,在具有正态分布随机参数的系统动力学模型和大量的Monte Carlo仿真实验基础上确证了研究结果。     

传统酸面团中植物乳杆菌发酵馒头抗氧化特性及挥发性风味物质特征

为了探究具有不同菌种关系的乳酸菌和酵母菌在泡菜发酵过程中的发酵性能,本实验选取不同食品来源的8株乳酸菌和5株酵母菌,通过代谢产物交叉培养及菌株共培养方法,筛选到一对具有互促关系的乳酸菌和酵母菌,即植物乳杆菌（Lactiplantibacillus plantarum）J05和酿酒酵母（Sacchromyces cerevisiae）Y21。分别从培养方式、接种顺序、接种比例等方面分析该组菌共培养关系,并测定了泡菜发酵过程中pH、总酸、还原糖含量、亚硝酸盐的含量。结果显示,添加酿酒酵母Y21静置培养无菌代谢产物对处于生长期的植物乳杆菌J05具有明显促生长作用,先接种酿酒酵母Y21后接种植物乳杆菌J05可促进两种菌的生长,筛选到两株菌共培养的最佳比例为30:1和40:1。在30:1的接种比例下,泡菜发酵进入稳定期后,与自然发酵组、单菌组、互抑组相比较,互促组pH维持在3.4~3.5之间,显著低于其他各组（P<0.05）;总酸含量最高值为1.25 mg/kg,显著高于其他各组（P<0.01）;还原糖含量较低,维持在0.10 g/100 g左右,亚硝酸盐峰值含量为5.38 mg/kg,显著低于除酿酒酵母Y21组外的其他三组（P<0.01）。本实验筛选所得互促菌组发酵性能较强,可缩短泡菜发酵周期,降低泡菜中亚硝酸盐含量。     

Headspace flavour compounds produced by yeasts and lactobacilli during fermentation of preferments and bread doughs.

Production of volatile flavour compounds during fermentation with pure cultures of Saccharomyces cerevisiae and Candida guilliermondii, Lactobacillus brevis and Lactobacillus plantarum have been investigated, using wheat doughs and several preferements as substrates. For yeast, preferments consisted of 10% (w/v) glucose, maltose and sucrose solutions, whereas for lactobacilli they consisted of supplemented and unsupplemented (3% and 10% (w/v)) glucose solutions, and a 10% (w/v) wheat flour slurry. Seven volatile compounds (acetaldehyde, acetone, ethyl acetate, ethanol, hexanal+isobutyl alcohol, and propanol) were detected when using yeasts. All these compounds, except propanol, appeared for all the substrates assayed, with ethanol as the predominant component. Generally, S. cerevisiae produced higher amounts of the different components than C. guilliermondii. Both yeasts produced larger amounts of volatile flavour compounds during fermentation in glucose and sucrose solutions than in maltose or wheat dough. In general the yeasts examined produced more flavour components than the lactobacilli. For the lactobacilli the highest number of volatile flavour compounds were observed for substrates containing flour.     

Antioxidant potential of aroma compounds obtained by limonene biotransformation of orange essential oil

The antioxidant activities of a limonene biotransformation extract and of some standard monoterpenes present in the extract were assessed using four antioxidant assays: total antioxidant capacity, based on the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay, lipid peroxidation by the thiobarbituric acid (TBA) assay, superoxide anion release by cultured leukemic cells and glutathione S-transferase (GSTs) activity. The limonene biotransformation extract had free radical-scavenging activity (EC₅₀ = 2.09%, v/v) and inhibited lipid peroxidation (IC₅₀ = 0.13%, v/v). The extract, perillyl alcohol and α-terpineol inhibited lipid peroxidation by ∼80% at a concentration of 0.02% (v/v). Perillyl alcohol and α-terpineol also reduced the release of superoxide anions by cultured leukemic cells, by 3- and 10-fold, respectively, at concentrations of <0.02% (v/v). The biotransformation extract inhibited the conversion of nitrophenyl acetate to p-nitrophenol in the glutathione assay by ∼50%. These results indicate that, in addition to monoterpenes, other non-volatile compounds may contribute to the antioxidant activity of the biotransformation extract.     

Effect of water addition on selective consumption (sorting) of dry diets by dairy cattle

The objective of this study was to determine whether adding water to a dry diet would reduce sorting and improve cow performance. Eighteen multiparous lactating Holstein cows were used in a cross-over design with 21-d periods. Treatments had the same dietary composition and differed only by adding water (WET) or not (DRY). Diets consisted of 10% alfalfa silage, 30% hay (approximately 80% grass and 20% alfalfa), and 60% concentrate [dry matter (DM) basis]. Dietary DM was 80.8% for DRY and 64.4% for WET. Both diets contained 16.9% crude protein and 24.3% neutral detergent fiber. Particle size was determined using the Wisconsin Particle Size Separator on the as-fed diets. The separator has five square-hole screens (Y(1) to Y(5)) with diagonal openings of 26.9 mm for Y(1), 18 mm for Y(2), 8.98 mm for Y(3), 5.61 mm for Y(4), and 1.65 mm for Y(5), and one pan. Sorting was calculated on a 60 degrees C DM basis (60DM). Predicted intake of Y(i) was calculated as the product of 60DM intake (60DMI) and the 60DM fraction of Y(i) in the total mixed ration for that screen. For DRY and WET, actual 60DMI by screen expressed as a percentage of predicted intake was 61.4% vs. 75.2% for Y(1), 83.8% vs. 98.6% for Y(2), 85.6% vs. 90.8% for Y(3), 95.2% vs. 96.0% for Y(4), 100.1% vs. 101.9% for Y(5), and 105.9% vs. 102.9% for pan, respectively. Adding water did not affect total DM intake (28.3 kg/d) or milk production (41.3 kg/d). Neutral detergent fiber intake was 6.42 kg/d for WET and 6.15 kg/d for DRY. Milk fat percentage tended to be higher (3.41% vs. 3.31%) when cows consumed WET vs. DRY. No differences in ruminal pH, NH(3), and volatile fatty acids were observed. Cows sorted against long particles in favor of shorter particles on both diets. Adding water to dry diets reduced sorting and tended to increase neutral detergent fiber intake and milk fat percentage.