Fructan Content of Rye and Rye Products

The fructan content of Finnish rye grains (13 samples, seven cultivars, harvested in 1998‐2000) varied at 4.6–6.6 g/100 g (db). Commercial whole grain rye flour and rye flakes had fructan content of 4 g/100 g, light refined rye flour had fructan content of 3 g/100 g, and rye bran had fructan content of 7 g/100 g. Fructan content as high as 23 g/100 g was detected in the water‐extractable concentrate of rye bran. Finnish soft rye bread and rye crisp bread contained 2–3 g of fructan/100 g. According to the suggested new definition of dietary fiber, fructans are also classified as dietary fiber. This means that the dietary fiber content of some cereal foods such as rye products may be increased by as much as 20% due to the presence of fructans in the grain.     

Effect of Drying Treatment Conditions on Sensory Profile of Germinated Oat

Germination and subsequent drying of oat produced significantly different sensory profiles depending on processing parameters such as drying speed and temperature profile. The most salient sensory attributes for processed oat were roasted odor and flavor, sweet taste, intense odor, intense aftertaste, and hard, crisp, brittle texture (P < 0.05). High temperatures (>85°C) were necessary to produce these sensory attributes, and quick drying after germination resulted in higher levels of intensity of favorable sensory attributes. The total amount of volatile compounds was higher in native (ungerminated) oat than in processed oat. During germination, and particularly during the drying treatment, the profile of volatile compounds changed. The most abundant volatile compounds responsible for odor were dimethyl sulfide, hexanal, pentanal, and iso butanal. The relative amount of dimethyl sulfide increased as a function of temperature in drying, whereas hexanal, pentanal, and isobutanal disappeared during heating, as did several other small ketones, alcohols, and esters. The germinated oat dried at high temperatures (65–93°C and 65–85°C) was perceived as being roasted, sweet, and nutty. Sensory and instrumental profile analyses of selected volatile compounds using partial least squares (PLS) regression techniques showed that these sensory attributes were clearly related to dimethyl sulfides and isobutanol. A moist and earthy odor was related to cymene, limonene, and isobutanal. Phenolic compounds significantly influenced oat flavor, whereas lipids had a negligible effect.     

Sourdough fermentation of wholemeal wheat bread increases solubility of arabinoxylan and protein and decreases postprandial glucose and insulin responses

Glycemic responses to most of the conventional breads are high, including breads made of wholemeal flour. Baking technology is known to affect these responses. The aim of the present study was to investigate effects of xylanase enzyme treatment and sourdough fermentation in wholemeal wheat bread baking on postprandial glucose and insulin responses and on in vitro protein digestibility. The wheat breads were made of 100% flour from peeled kernels by a straight dough or sourdough fermentation method, and with or without using xylanase during mixing of dough. Standard white wheat bread was used as a reference. All test bread portions contained 50 g available carbohydrate and were served in random order to eleven insulin resistant subjects. Blood samples for measuring glucose and insulin concentrations were drawn over 4 h. The sourdough wholemeal wheat bread resulted in the lowest postprandial glucose and insulin responses among the four tested breads (treatment × time; p = 0.000 and p = 0.022, respectively). There were differences in solubility and depolymerisation of protein and arabinoxylan among the breads but these did not fully explain the in vivo findings. In conclusion, the health effects of wholemeal wheat bread can be further improved by using sourdough process in breadmaking.     

Influence and Interactions of Processing Conditions and Starter Culture on Formation of Acids,Volatile Compounds,and Amino Acids in Wheat Sourdoughs

The aim of this work was to study the influence of process parameters and the starter culture on the characteristics of wheat sourdough by using response surface methodology. Influence of fermentation temperature (16–32°C), ash content of flour (0.6–1.8%), and fermentation time (6–20 hr) were considered as independent factors and their effects were studied in sourdough fermented with Lactobacillus plantarum, L. brevis, Saccharomyces cerevisiae, or with a combination of yeast and lactic acid bacteria. Formation of acidity, free amino acids, and volatile compounds were considered the main responses. A possibility to enhance formation of potential flavor compounds and precursors without excessive acidity formation in wheat sourdoughs was established. The total amount of amino acids increased by 25–50%, depending on the strain and fermentation conditions. The total amount of volatile compounds increased seven‐ to 100‐fold, depending on the strain and fermentation conditions. Sourdough started with S. cerevisiae was an effective way to optimize the amount of volatile compounds without excessive acidity formation in appropriate processing conditions. Ash content of flour and fermentation time were the most significant factors to modify metabolic activity of wheat sourdoughs. Frequent interactions between the studied factors were observed on the formation of acidity, amino acids, and volatile compounds with most of the strains studied. Possibility to improve current industrial fermentation processes and control flavor attributes of breads by using optimized sourdough was established.     

Is GRO J1744-28 a strange star?

The unusual hard x-ray burster GRO J1744-28 recently discovered by the Compton Gamma-Ray Observatory can be modeled as a strange star with a dipolar magnetic field of 相似文献   

Differences Between Sensory Profiles and Development of Rancidity During Long‐Term Storage of Native and Processed Oat

Changes in the sensory attributes, lipid composition, and amounts of volatile and phenolic compounds of native and processed (germinated and dried) crushed oat were followed during a 12‐month storage period. The influence of the chemical attributes on the sensory profiles of oats was analyzed by statistical multivariate techniques (PLS regression). During the storage period, significant changes in the sensory profiles of the native and processed oat groats were observed. The stability of oat groats was significantly increased through germination and subsequent drying because the chemical changes causing rancidity and bitterness developed more slowly in the processed oat when compared with the native oat. In native oat, the most intensive changes due to deteriorat ion had already occurred after one month of storage, whereas in processed oat, these changes were perceived considerably later. Stored oat that had deteriorated was evaluated as being musty and earthy in odor and bitter and rancid in flavor. The accumulation of free fatty acids and volatile compounds related to lipid oxidation were closely correlated with the development of the undesired sensory attributes described above. The total amount of phenolic compounds, as well as the volatile aromatic and branched chain compounds derived mainly from protein degradation, showed a significant relationship with favorable sensory attributes such as roasted odor and flavor. Lipid oxidation occurred during the storage and was observed both in the polar and in the nonpolar lipid classes of native oat, whereas in the processed oat, these changes were nonsignificant. Photo‐oxidation of acylated fatty acids may significantly contribute to the development of volatile lipid oxidation products during storage.     

Effect of Partial Gelatinization and Lipid Addition on α‐Amylolysis of Barley Starch Granules

The effect of partial gelatinization with and without lipid addition on the granular structure and on α‐amylolysis of large barley starch granules was studied. The extent of hydrolysis was monitored by measuring the amount of soluble carbohydrates and the amount of total and free amylose and lipids in the insoluble residue. Similarly to the α‐amylolysis of native large barley starch granules, lipid‐complexed amylose (LAM) appeared to be more resistant than free amylose and amylopectin. Partial gelatinization changed the hydrolysis pattern of large barley starch granules; the pinholes typical of α‐amylase‐treated large barley starch granules could not be seen. Lipid addition during partial gelatinization decreased the formation of soluble carbohydrates during α‐amylolysis. Also free amylose remained in the granule residues and mostly amylopectin hydrolyzed into soluble carbohydrates. These findings indicate that lysophospholipid (LPL) complexation with amylose occurred either during pretreatment or after hydrolysis, and free amylose was now part of otherwise complexed molecules instead of being separate molecules. Partial gelatinization caused the granules to swell somewhat less during heating 2% starch‐water suspensions up to 90°C, and lipid addition prevented the swelling completely. α‐Amylolysis changed the microstructure of heated suspensions. No typical twisting of the granules was seen, although the extent of swelling appeared to be similar to the reference starch. The granules with added LPL were partly fragmented after hydrolysis.     

Influence of preservation methods on the quality of colostrum sourced from New Zealand dairy farms

Abstract

AIMS: To assess the effect of two temperatures (ambient temperature and 4°C), three preservation methods (no preservative, yoghurt and potassium sorbate), and two periods of storage (3 and 7 days) on Brix and total bacterial and coliform counts of colostrum collected from New Zealand dairy farms.

METHODS: One litre of colostrum destined to be fed to newborn calves was collected from 55 New Zealand dairy farms in the spring of 2015. Six aliquots of 150 mL were obtained from each colostrum sample, with two aliquots left untreated, two treated with potassium sorbate and two with yoghurt, and one of each pair of aliquots stored at ambient temperature and the other at 4°C. All samples were tested for Brix, total bacterial counts and coliform counts before treatment (Day 0), and after 3 and 7 days of storage. The effect of preservation method and storage temperature on the change in Brix, bacterial and coliform counts after 3 or 7 days of storage was analysed using multivariable random effects models.

RESULTS: For all outcome variables there was a temperature by preservation interaction. For aliquots preserved with potassium sorbate, changes in Brix and bacterial counts did not differ between aliquots stored at ambient temperature or 4°C, but for aliquots preserved with yoghurt or no preservative the decrease in Brix and increase in bacterial counts was greater for aliquots stored at ambient temperature than 4°C (p<0.001). For aliquots preserved with potassium sorbate, coliform counts decreased at both temperatures, but for aliquots preserved with yoghurt or no preservative coliform counts increased for aliquots stored at 4°C, but generally decreased at ambient temperatures (p<0.001). There was also an interaction between duration of storage and temperature for bacterial counts (p<0.001). The difference in the increase in bacterial counts between aliquots stored at 4°C and ambient temperature after 3 days was greater than between aliquots stored at 4°C and ambient temperature after 7 days.

CONCLUSIONS AND CLINICAL RELEVANCE: Use of potassium sorbate to preserve colostrum for 3 or 7 days resulted in little or no reduction in Brix and a lower increase in total bacterial counts than colostrum stored without preservative or with yoghurt added. Colostrum quality was not affected by storage temperature for samples preserved with potassium sorbate, but storage at 4°C resulted in better quality colostrum than storage at ambient temperatures for colostrum with no preservative or yoghurt added.     

Associations between management practices and colostrum quality on New Zealand dairy farms

Abstract

AIMS: To describe colostrum quality in spring-calving dairy herds in New Zealand, in terms of Brix, pH and total and coliform bacterial counts and to investigate associations between farm management practices and these measures of colostrum quality.

METHODS: In June 2015, commercial dairy farms (n=105), located in North and South Islands of New Zealand, were visited shortly after the first cows had calved, and when approximately 50% and 80% of the herd had calved (early, middle and late visits). One litre of pooled colostrum that was being fed to newborn calves was collected at each visit and used to determine Brix, pH, total bacterial and coliform counts. A survey of calf management practices was conducted with the herd manager or calf rearer after the final visit.

RESULTS: Of 298 pooled colostrum samples tested 29/298 (9.7%) had Brix >22%. Brix was higher on farms where calves were picked up twice daily compared with once daily (18.2 (95% CI=16.5–19.9)% vs. 15.9% (95% CI=15.2–16.6)%; p=0.012), and was lower where first milking colostrum was combined with colostrum obtained at later milkings (15.0 (95% CI=13.9–16.1)%) compared with where it was not (16.9 (95% CI=16.3–17.6)%; p=0.002). Vaccination of all cows against calf diarrhoeal pathogens was associated with increased Brix compared with no vaccination (18.1 (95% CI=16.6–19.6)% vs. 16.3 (95% CI=15.6–17.0)%; p=0.033). Mean pH of samples tested decreased from 5.97 (95% CI=5.84–6.09) to 5.58 (95% CI=5.45–5.71) for early and late-season visits, respectively (p<0.001). Of 268 samples tested, 23 (8.6%) had bacterial counts below the recommended threshold of 1.00×10⁵ cfu/mL. Mean bacterial counts increased from 2.75 (95% CI=1.80–3.70)×10⁸ to 4.99 (95% CI=3.95–6.03)×10⁸ cfu/mL for early and late-season visits, respectively (p<0.001). Of 259 samples tested, 23 (8.9%) had coliform counts below the recommended threshold of 1.00×10⁴ cfu/mL.

CONCLUSIONS AND CLINICAL RELEVANCE: On a large majority of dairy farms included in this study the pooled colostrum fed to newborn calves had sub-optimal Brix and excessive bacterial counts. Farm-level risk factors such as twice daily pick up of calves from the paddocks, herd vaccination and feeding pooled colostrum that did not combine colostrum obtained at later milkings with first milking colostrum were associated with colostrum quality measures.     

Characterization and fate of black currant and bilberry flavonols in enzyme-aided processing

The fate of black currant ( Ribes nigrum L.) and bilberry ( Vaccinium myrtillus L.) flavonols in enzyme-aided processing was studied. The flavonols were quantified and characterized by high-performance liquid chromatography equipped with a diode array detector and an electrospray ionization mass spectrometer. A tentative identification for 14 black currant and 19 bilberry flavonols is presented representing 11 previously unpublished conjugates. For the first time in any berry, the presence of laricitrin conjugates is reported. The enzyme-aided processing affected the flavonol extractability, elevating the yield in juices and decreasing that in press residues. Importantly, no significant loss of the berry flavonols was observed during the experiments, although some hydrolysis of flavonol conjugates was recorded. To maximize the effect on flavonol extractability, higher enzyme dosages were needed for black currants than for bilberries. The data show that the flavonol extractability and hydrolysis are dependent on the texture of raw material, the glycosylation pattern of the conjugates, and the activity profile of the enzyme preparation.