The influence of fermentation temperatures (8°C, 16°C, and 32°C) and yeast levels (2%, 4%, and 6% of the flour) on the formation of volatile compounds in the crust of whole meal wheat bread was investigated. The fermentation times were regulated to optimum bread height for each treatment. The volatile compounds were extracted by dynamic headspace extraction and analyzed by gas chromatography-mass spectrometry. The results were evaluated using multivariate data analysis and ANOVA. In all crust samples 28 volatile compounds out of 58 compounds were identified and the other 30 compounds were tentatively identified. Higher fermentation temperatures promoted the formation of Maillard reaction products 3-methyl-1-butanol, pyrazine, 2-ethylpyrazine, 2-ethyl-3-methylpyrazine, 2-vinylpyrazine, 3-hydroxy-2-butanone, 3-(methylsulfanyl)-propanal, and 5-methyl-2-furancarboxaldehyde whereas at lower temperature (8°C) the formation of 2- and 3-methylbutanal was favored. Higher levels of yeast promoted the formation of 3-methyl-1-butanol, 2-methyl-1-propanol and 3-(methylsulfanyl)-propanal, whereas hexanal was promoted in the crust fermented with lower yeast level.
Cereal Chem. 93(2):209-216The influence of fermentation temperatures (8, 16, and 32°C) and yeast levels (2, 4, and 6%) on the formation of volatile compounds in the crumb of whole-meal wheat bread was investigated. Volatile compounds were extracted by dynamic headspace extraction and analyzed by gas chromatography-mass spectrometry. Results were evaluated with multivariate data analysis and ANOVA. Bread fermented at a high temperature (32°C) had higher peak areas of the Maillard reaction products 2-furancarboxaldehyde, 2-acetylfuran, 2-methylpyrazine, and phenylacetaldehyde compared with bread fermented at lower fermentation temperatures. Bread fermented at low temperatures (8 and 16°C) was characterized by having higher peak areas of the fermentation products 3-methylbutanal, 2-methylbutanal, ethyl acetate, ethyl hexanoate, ethyl propanoate, and 3-methylbutanol. Fermentation of bread with 6% yeast resulted in a higher peak area of the important fermentation product 2-phenylethanol. It also reduced the peak areas of important lipid oxidation products. The peak area of 2,3-butanedione was also relatively higher in bread fermented with 6% yeast compared with lower yeast levels; however, an interaction was seen between the high yeast level and all three fermentation temperatures. In contrast, fermentation with a low yeast level (2%) resulted in bread with relatively higher peak areas of 2and 3-methylbutanal, as well as (E)-2-nonenal and (E,E)-2,4-decadienal, which are important lipid oxidation compounds in bread. † Corresponding
The degradation of inositol hexakisphosphate (IP6) was evaluated in whole meal wheat dough fermented with baker's yeast without phytase activity, different strains of Saccharomyces cerevisiae (L1.12 or L6.06), or Pichia kudriavzevii with extracellular phytase activity to see if the degradation of IP6 in whole meal dough and the corresponding bread could be increased by fermentation with phytase‐active yeasts. The IP6 degradation was measured after the dough was mixed for 19 min, after the completion of fermentation, and in bread after baking. Around 60–70% of the initial value of IP6 in the flour (10.02 mg/g) was reduced in the dough already after mixing, and additionally 10–20% was reduced after fermentation. The highest degradation of IP6 was seen in dough fermented with the phytase‐active yeast strains S. cerevisiae L1.12 and P. kudriavzevii L3.04. Activity of wheat phytase in whole meal wheat dough seems to be the primary source of phytate degradation, and the degradation is considerably higher in this study with a mixing time of 19 min compared with earlier studies. The additional degradation of IP6 by phytase‐active yeasts was not related to their extracellular phytase activities, suggesting that phytases from the yeasts are inhibited differently. Therefore, the highest degradation of IP6 and expected highest mineral bioavailability in whole meal wheat bread can be achieved by use of a phytase‐active yeast strain with less inhibition. The strain S. cerevisiae L1.12 is suitable for this because it was the most effective yeast strain in reducing the amount of IP6 in dough during a short fermentation time.
Water spinach (Ipomoea aquatic Forsk.) is a food for human beings and animals. It is rich in minerals, protein, dietary fibre, with high moisture content. The work was undertaken to determine contents of K, Ca, Mg, Na & P in the stems, leaves and petioles of water spinach. Atomic absorption spectrometry (AAS) and Inductive Couple Plasma (ICP) were used to determine concentration of nutrients, where one way ANOVA was applied to analyse if there is any significant differences in the macronutrient contents amongst the leaves, petioles and stems of the water spinach. If any of the results showed significant differences, Turkey post-hoc HSD test (p<0.05%) was adopted to separate the means. In addition, Pearson’s Correlation Coefficient Test was conducted between the plant macronutrients samples (leaves + stem + petioles combined) and water macronutrients data run to determine their relationships. In addition, purpose of this study is to highlight to the public which parts of the plant should be consumed and also to indicate the relationship of Water Spinach with its growing medium. The K concentration was higher than the other elements and maximum concentration was in petioles (432+27.45 mg·L-1) and stems (424.60+14.19 mgL-1). The element with the least concentration was Na (3.10+0.40 mgL-1), in the petiole. There was no difference in Mg content in leaves, petioles and stems (avg. 28.55+1.61 mgL-1). High amounts of Ca (150+0.10 mgL-1) and low amounts of P (41.11+0.01 mgL-1) were in pond water. A positive correlation of each nutrient occurred between water spinach and pond water.
The study aimed to determine the characteristics of gelatin from water buffalo (Bubalus bubalis) skin pre-treated with NaOH and Ca(OH)2 at different concentrations (0.3 M, 0.5 M and 0.7 M) and extracted at 65˚C for 6 hrs and 24 hrs respectively. The gelatin obtained was evaluated for its moisture, protein and ash content, UV-vis absorption value, colour, emulsifying and foaming properties. The highest yield (20.25%) was observed for gelatin extracted by 0.5 M NaOH at 24 hrs extraction time. For alkaline pre-treatment, it was found that NaOH was more efficient than Ca(OH)2 in terms of preparing the skin for subsequent extraction process. The protein content of the extracted gelatin samples was in the range of 71.76% - 87.83%, showing that the varying processing conditions are sufficiently to recover protein from the raw material. Ash content for all samples was in agreement with USDA standard, which was below than 3%. The extracted gelatin had varying pH values which were from 5.47 to 7.02. The gelatin was colourless with ‘L’ values of more than 80, except for 0.7 M Ca(OH)2 at 24 hrs which showed slightly darker properties. The intensity of the UV-vis absorption spectrum showed that a high absorption peak was observed at 6 hrs of extraction time (230 – 250 nm) compared to 24 hrs extraction time. Emulsifying properties of buffalo gelatin increased with increasing concentrations of alkaline except for 0.7 M NaOH and 0.7 M Ca(OH)2 for both extraction time. Meanwhile, foam expansion of the gelatin extracted from the different extraction conditions was observed to have a significant difference (p < 0.05) for all samples. To our knowledge, buffalo skin has the potential to be an alternative source of gelatin in the diversified industrial application by modifying the extraction conditions in order to produce gelatin with desired quality.
This study aimed to evaluate the microbiological quality of commercial fresh fish. A total of 7 marine fish species (n = 9 per species) were collected and sold from the wet market in Kota Kinabalu, Malaysia. The prevalence of Pseudomonas spp. (100%) in fish was the highest followed by Aeromonas spp. (58%), Escherichia coli (46.03%), Vibrio spp. (22%), and Salmonella spp. (6.35%). The mean of the total plate counts in gill, gastrointestinal tract, skin and flesh samples were 5.32 ± 0.69 log cfu/g, 4.81 ± 0.81 log cfu/g, 4.23 ± 0.58 log cfu/cm2 and 3.99 ± 0.58 log cfu/g, respectively. Therefore, fresh fish sold in Kora Kinabalu has the potential to be contaminated with pathogenic bacteria. Effective control measures are required to prevent contamination during postharvest fish processing and consumers are advised to avoid eating raw fish to reduce health hazards from bacteria.
White mulberry (Morus alba L.) is a berry native to China which fruit is usually eaten fresh or after processed. Its bioactive compounds vary depending on species, cultivation, location and others. In this study, the total flavonoids content, total phenolic content, total anthocyanins content and antioxidant activity of Morus alba L. fruit grown in Tuaran, Sabah were analyzed. Fruit was extracted with 60°C hot water and 80% ethanol, while the total bioactive compounds analysis utilized aluminum chloride, Folin-Ciocalteu and pH differential method in determining the flavonoids, phenolic, and anthocyanins content. Their antioxidant activity was determined using Free Radical Scavenging 2.2-Dyphenyl-1-Pikrilhidrazil (DPPH), Ferric Reduction Antioxidant Power (FRAP) and Radical Cation 2,2’-Azino-bis (3-ethylbenzthiazoline-6-sulphonic acid (ABTS) assay. As a result, significantly higher (p < 0.05) content of total flavonoids (104.34 mg QE mg−1), phenolic (1.21 mg GAE mg−1) and anthocyanins (0.74 mg c-3-ge mg−1) were obtained from ethanolic extract than the hot water extract. Also, significantly higher (p < 0.05) antioxidant activity was observed in ethanolic extract for DPPH (0.50 mg mL−1), FRAP (3.74 mm Fe (II) g−1) and ABTS (6.05 mg AEAC g−1). Data showed that ethanol solvent (80%) is a better solvent for Morus alba L. fruit’s extraction.
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