Use of Candida tropicalis ATCC 9968 to Adjust the pH of a Natural Lactic Acid Fermentation of Cornmeal

After 3 days of a natural lactic acid fermentation of whole kernel cornmeal, the pH was 3.78 with a titratable acidity of 0.91% at 32°C (1:4 w/v solids to water). These solids were diluted (1:12 w/v), autocalved at 121°C for 15 min and fermented with C. tropicalis for 7 days at 32°C, bringing the pH to 6.5 and 0.03% acidity. After both fermentations, the % relative nutritive value increased significantly (from 74.09% to 81.22%) and so did riboflavin (from 0.22 to 0.56 mg/100g). Both thiamin and niacin decreased significantly (0.42 to 0.20 mg/100g and 2.13 to 1.94 mg/100g, respectively).     

Production of ribonucleotides by autolysis of Hansenula anomala grown on Korean ginseng steaming effluent

Hansenula anomala KCCM 11473, which grew well in Korean ginseng steaming effluent, was selected for the production of 5'-ribonucleotides. This strain had high RNA content. Optimal autolysis conditions were established to produce 5'-ribonucleotides (13.9 approximately 28.5 mg/g of biomass) at 55 degrees C and pH 5.0 for 24 h. 5'-Phosphodiesterase and adenyl deaminase were not effective in increasing the yield of 5'-ribonucleotides, but the yield of IMP increased significantly only after the addition of 1.0% adenyl deaminase.     

Enzymatic Production of High-Protein Amaranth Flour and Carbohydrate Rich Fraction

The basic conditions of an enzymatic process to produce high-protein amaranth flour (HPAF) and carbohydrate rich fraction (CRF) from raw flour were determined. Commercial preparations of α-amylase and glucoamylase were used. Conditions for both enzymes were: 20% (w/v) slurries of gelatinized whole flour and 0.10% (v/w) enzyme; for amylase, pH 6.5, 70°C and 30 min liquefaction time; for glucoamylase, pH 4.5, 60°C and 60 min. The yield of HPAF was 38–39%. HPAF from both enzymes had 26–28% protein, 10–16% fat and 40–52% starch. Protein digestibility (76%) and reactive lysine (6.6–7.1 g/100g protein) of HPAF were comparable to raw flour. CRF had a 17–21 dextrose equivalent.     

The effect of pH,sodium chloride,sodium nitrite and storage temperature on the growth of Clostridium perfringens and faecal streptococci in laboratory media

The effects of salt concentration (1–12% w/v) in combination with unheated sodium nitrite (0–400 μg/ml) on growth of mixed strains of Clostridium perfringens and of faecal streptococci at three pH values (5.6, 6.2, 6.8) and storage temperatures ranging from 10°C to 35°C is reported. At pH 6.2, following storage at 15°C, 1% salt and 50 μg/ml nitrite inhibited growth of C. perfringens. At 20°C and pH 6.2, 200 μg/ml nitrite plus 3% salt, or 50 μg/ml plus 4% salt were required to inhibit growth. Growth of C. perfringens was prevented by levels of curing salts used commercially providing the pH was 6.2 or below. At pH 6.8 or above at least 4% salt and 50 μg/ml nitrite was required to prevent growth at 20°C. The faecal streptococci grew in medium containing 6% salt and 400 μg/ml nitrite irrespective of pH or storage temperature. In 8% salt growth was prevented by storing at or below 17.5°C or, if pH was 6.2 or lower, by adding 200 μg/ml nitrite irrespective of storage temperature. Growth of faecal streptococci was not controlled by concentrations of curing salts which would be acceptable in meat products.     

Postmortem Changes of Cultivated Atlantic Salmon and Their Effects on Salt Uptake

Rigor mortis of cultivated Atlantic salmon (Salmo salar) began to set in 8h after death and was fully resolved 60–70h after death during storage at 0°C. Maximum muscle contraction was observed 24–30h after death. ATP content decreased from 7.25 to 0.14 to 0.09 μmol/g fish from pre-rigor mortis to in-rigor mortis to post-rigor mortis state. The inosine and hypoxanthine contents increased from 0 to 1.20 to 4.06 μmol/ g fish and from 0.08 to 0.33 to 0.84 μmol/g fish during 60h storage, respectively, during 60h of storage at 0°C. Postmortem changes affected salt uptake. The equilibrium salt concentrations of pre-rigor, in-rigor and post-rigor mortis salmon were 0.53, 0.66 and 0.75 g/g salt-free solids, respectively, in a 20% (w/v) sodium chloride solution at 10°C.     

Effect of gelation factors on the formation and characteristics of protease‐induced whey protein gel

Whey protein gel formed at 10% (w/v) whey protein concentration, 0.5% E/S, pH 7.0, 55°C and 2.5 mM CaCl₂ concentration had an average particle size of 23.46 μm, hardness of 0.46, cohesiveness of 0.13 and adhesiveness of 1.40, and the gel showed semisolid, smooth and creamy texture. There were no distinct changes in gel textural properties after heating at 80 and 90°C for 5 min, respectively, or being kept at 4°C for 1 month. The textural properties of the gel showed no significant difference after its pH was adjusted to 4.5, 5.5 and 7.5 compared with that of pH 6.5 (control gel). However, the average particle size significantly increased after being adjusted to pH 4.5 and pH 5.5. Transmission electron micrographs showed that protease‐induced gel possessed much looser aggregate structure compared with heat‐induced compact gel, which may give support to its potential application in low‐fat foods that no need of extensive heating.     

The simultaneous saccharification and fermentation of malt dust and use in the acidification of mash

In brewing, the mash or wort is frequently acidified by the addition of lactic acid or the bioacidification of the mash. The present study provides an alternative approach for mash or wort acidification by the simultaneous saccharification and fermentation (SSF) of malt dust. In this method, fermentable carbohydrates released by the enzymatic breakdown of the cellulosic portion of the malt dust are converted to lactic acid by lactic acid bacteria. The effect of temperature, ranging between 45 and 51°C, solid loading of malt dust at 2, 5 and 10% (w/v) on a dry basis, and enzyme loading at 0.65, 2.6 and 6.5 filter paper units (FPU) per gram malt dust on SSF and change in pH in mash acidification were examined. The final pH and lactic acid concentration and final glucose concentration of the SSF media were significantly affected by the temperature of the process (p < 0.05). The highest lactic acid titre (9.7 g/L) and the lowest pH (3.12) were obtained by SSF of 10% (w/v) malt dust at 45°C with 6.5 FPU/g. The pH of the mashing solution [containing 20% (w/v) ground malt] decreased to around 5.4 and 5.2 after adding 1.9 and 2.9% of SSF media with pH 3.39. © 2019 The Institute of Brewing & Distilling     

The effect of pH,water activity,sodium nitrite and storage temperature on the growth of enteropathogenic Escherichia coli and salmonellae in a laboratory medium

The effect of salt concentration (1–10% w/v) in combination with sodium nitrite (0–400 μg/ml) on growth of mixed strains of Salmonella and enteropathogenic E. coli at three pH values (5.6, 6.2, 6.8) and storage temperatures ranging from 10°C to 35°C is reported. E. coli tended to be more tolerant of salt and nitrite than Salmonella.     

Effect of Soluble Dietary Fibers on Lipase-catalyzed Hydrolysis of Tributyrin

The ability of soluble fibers to inhibit calf pregastric lipase (CPGL)‐catalyzed hydrolysis of tributyrin (TBG) has been measured at pH 6.5, 37 °C (CPGL 0.02 mg/mL). Fibers tested were pectin, carboxymethylcellulose (CMC), carrageenan, and gum arabic. The fibers (5 g/L), solubilized in Bis‐Tris buffer (50 mM, pH 6.5) at 4 °C for either 15 min or 24 h, were added to an emulsion containing TBG, before initiating the reaction by addition of CPGL. An immediate inhibitory effect of 8% to 19% was observed. The value of the CPGL–pectin dissociation constant, K_i, was 0.76 to 2.34 mM. Dialysis of pectin solution reduced the inhibitory effect by 14% and the concentration of galacturonic acid by 15%.     

The emulsifying properties of Persian gum (Amygdalus scoparia Spach) as compared with gum Arabic

The current study compares the emulsifying properties of Persian gum (PG) and gum Arabic (GA) in emulsions. The effects of concentration (0.5–3% w/v PG, 2.5–15% w/v PG), pH (2–7), ionic strength [NaCl, CaCl₂ (0–300 mM)], and temperature (40–90°C) were investigated. The surface–volume mean diameter (D₃₂) of the emulsions showed that the minimum values were 9.89 ± 0.68 and 4.52 ± 0.03 µm for emulsions containing 1.5% w/v PG and 15% w/v GA, respectively. In addition, the zeta potential of PG and GA emulsion changed from ?23.5 to ?39.5 and ?30.5 to ?46.0 mV, respectively. The interfacial tensions of PG and GA emulsions were varied in the ranges of 34.0–15.0 and 29.0–9.0 mN/m, respectively. Changes in the D₃₂ value of GA emulsions showed were not significantly different (p > 0.05) with respect to the effects of pH, NaCl, CaCl_2, and temperature. The NaCl concentration had no significant effect on D₃₂; but its value decreased from 13.11 to 5.70 µm as the CaCl₂ concentration increased. The interfacial tension of PG significantly increased with decreasing pH 7–2 and increasing 0–300 mM salts. After heating (25–90°C), the D₃₂ values of PG and GA emulsions changed to 11.04–14.54 and 4.21–4.21 μm, respectively. The results of this study can be useful for the application of PG as an emulsifier in beverage emulsions.     

Response surface optimization for cellulose production from agro industrial waste by using new bacterial isolate <Emphasis Type="Italic">Gluconacetobacter xylinus</Emphasis> C18

In the present investigation, a low-cost medium prepared from molasses and corn steep liquor was used for the bacterial cellulose production by using an isolated bacterial strain. This bacterium, identified as Gluconacetobacter xylinus C18, was isolated from Indian fruit waste (rotten grapes). The process of cellulose production from the isolated bacterial strain was optimized using response surface methodology based on the central composite rotatable design. The optimum parameters for maximum bacterial cellulose production (4.34 g/L) obtained were sugarcane molasses concentration 10.77% (w/v) supplemented with 12.47% (v/v) corn steep liquor concentration at 31 °C, pH 6.5, and incubation time of 172 h. The structure of cellulose was characterized and confirmed by using SEM and FT-IR spectroscopy.     

Effect of modifiers on thermal behaviour of Se in acid digestates and slurries of vegetables by graphite furnace atomic absorption spectrometry

The influence of sample preparation strategy of vegetables on the electrothermal behaviour of Se without and with chemical modifiers such as Pd(NO₃)₂, Pd(NO₃)₂ + Mg(NO₃)₂, Pd(NO₃)₂ + Cd(NO₃)₂, pre-reduced Pd, Mg(NO₃)₂, and Ni(NO₃)₂ was investigated. Acid digestates and slurries of vegetables (0.1% m/v in 1% v/v HNO₃ + 0.005% v/v of Triton X-100) were used to prepare reference solutions or slurries. For 10 μl of each modifier tested, pyrolysis and atomization temperatures were evaluated using pyrolysis and atomization curves, respectively. Best conditions, such as thermal stability, signal profile, repeatability and sensitivity were attained using Pd(NO₃)₂ as chemical modifier. The following heating program (temperature, ramp/hold time) of the graphite tube of the Varian SpectrAA-800Z atomic absorption spectrometer was used: dry step (85 °C, 5/0 s; 95 °C, 40/0 s; 120 °C, 10/5 s); pyrolysis step (1400 °C, 10/3s); atomization step (2200 °C, 1/2 s); clean step (2600 °C, 2/0 s). This pyrolysis temperature is 800 °C higher than when measuring without any modifier. For 20 μL sample volume and 10 μg Pd(NO₃)₂, analytical curves in the 3.0–30 μg Se l⁻¹ range were obtained. The method was applied for Se determination in acid digestates and slurries of 10 vegetable samples and one standard reference material (rice flower) and results were in agreement at 95% confidence level. Recoveries varied from 89 to 95% for spiked samples. The lifetime of the graphite tube was ca. 250 firings and the relative standard deviations (n=12) for a typical acid digestate and slurry containing 20 μg Se l⁻¹ were 3.8% and 8.3%, respectively. The limits of detection were 2.0 μg Se l⁻¹ and 0.6 μg Se l⁻¹ Se for digestates and slurries, respectively.     

Control of Enzymatic Browning in Processed Mushrooms (Agaricus bisporus)

Control of polyphenol oxidase (E.C. 1.14.18) activity by the use of citric acid was investigated. The enzyme was inactivated at pH 4.0 and was stable to 10 min exposures at 25°C in the pH range 4.0–8.0. At pH 6.5 the enzyme was active at 45°C but not at 70°C and thermal inactivation followed pseudo first-order kientics. At pH 6.5 the activation energy (E_a) for enzyme inactivation was 41.1 Kcal/mole while at pH 3.5 two rate constants and hence two values for E_a were observed. Between 0–5 min E_a for inactivation of polyphenol oxidase was 8.7 Kcal/mole and >5 min Ea was 21.8 Kcal/mole.     

The influence of temperature on shortening and rigor onset in beef muscle

At sufficient ATP concentration and temperatures below about 15°C, pre-rigor beef muscles (neck muscles) contract; this phenomenon is known as cold shortening. There is also a contracture at higher temperatures occurring just before rigor onset which is called rigor shortening. While rigor shortening starts in neck muscles at pH around 6·3–6·0 and at about 2 μMol ATP/g muscle, cold shortening can begin at pH around 7·0 and the full ATP concentration (4 μMol ATP/g) in the muscle. Shortening can take place as long as there is no irreversible formation of the actomyosin complex in the muscle, i.e. before rigor onset occurs, which can be measured by intermittent loading of the muscle. The degree of extensibility which follows starts to decrease at the moment of rigor onset. This irreversible loss of extensibility at temperatures between the freezing point (?1°C) and physiological temperatures (38°C) starts at various pH values and ATP concentrations in the muscle. At 38°C the rigor onset occurs at pH 6·25 and about 2 μMol ATP/g muscle, dropping at 15°C to pH 5·75 and 1 μMol ATP/g muscle. At 0°C, as at all temperatures below 10°C, the loss of extensibility at medium loads (about 250 g/cm²) begins shortly after cold shortening. This loss of extensibility is reversible by increasing the load or raising the temperature. The irreversible loss, or rigor onset, however, occurs at 0°C with pH of 6·1–6·2 and 1·8–2·0 μMol ATP/g muscle. Thus, the onset of rigor is influenced by more than one factor. Temperature, pH and ATP concentration each play a rôle.Maximum loss of extensibility or completion of rigor is reached between 10°C and 38°C at pH 5·5–5·6 and less than 0·5 μMol ATP/g muscle. At 0°C the completion of rigor takes place at pH 6·0, but still at 0·5 μMol ATP/g muscle. The latter fact shows that the completion of rigor is solely dependent on the ATP concentration in the muscle; nevertheless, the pH of rigor completion is higher in the extreme cold shortening range. This is apparently due to a different pH/ATP relationship in muscles at low temperatures.The results are discussed in terms of changes in the concentration of Ca²⁺ ions and ATP.The results are of particular interest for the handling of hot-boned meat; that is, for both the cooling of pre-rigor muscle and the use of hot-boned meat for processing.     

Downstream Processing of the Hydrolysate from Cassava Fibrous Waste in the Production of Confectioner's Syrup

The acid hydrolysis of starch present in cassava fibrous waste results in a formation of brownish yellow hydrolysate due to the use of higher acid concentration than that needed in case of pure starch. Thus, it dictates application of stronger downstream processing unit operations such as deproteinization, clarification and decolouration. Among the various deproteinizing agents evaluated, bentonite and kaolin were found to be the best and their use resulted in the removal of 20% protein and 60–70% red as well as yellow colours. Kaolin was selected based on economic considerations. The data indicated that 5% (w/v) kaolin, 10 min contact time at 25°C and a pH of 1.0–1.5 of the hydrolysate were suitable. For complete decolouration, 0.5% (w/v) activated carbon at 25°C with a contact time of 30 min was needed. Treatment with activated carbon also results in protein removal and is maximum at 40°C. These stronger down-stream processing unit operations lead to an acceptable product conforming to the standard.     

Production and Application of a Maltogenic Amylase by a Strain of Thermomonospora viridis TF-35

An extracellular and thermostable maltogenic amylase-producing moderate thermophile (Thermomonospora viridis TF-35), which grew well at 28–60°C, with optima at 45°C and pH 7, was isolated from soil. Maximal enzyme production was attained after aerobical cultivation for 32 h at 42°C with a medium (pH 7.3) composed of 2% (w/v) soluble starch, 2% gelatin hydrolyzate, 0.1% K₂HPO₄ and 0.02% MgSO₄ · 7H₂O. The partially purified enzyme, which was most active at 60°C and pH 6.0 and stabilized with Ca²⁺, converted about 65, 80, 75, 75, 65 and 60% of maltotriose, maltotetraose, maltopentaose, amylose, amylopectin and glycogen into maltose as a major product under the conditions used, respectively. Glucose and small amounts of maltooligosaccharides were also formed concomitantly as by-products. The molar ratio of maltose to glucose from maltotriose were larger than 1 during all stages of the hydrolysis. About 70 and 76% of 25% (w/v) potato starch liquefites having a 3.5 DE value were converted into maltose by the enzyme in the absence and presence of pullulanase during the saccharification, respectively. About 90 and 94% of the starch liquefites were also converted into maltose with relatively low contents of maltooligosaccharides by the cooperative 2 step reaction with the enzyme after obtaining starch hydrolyzates containing about 85 and 90% maltose by the simultaneous actions of soybean ß-amylase and debranching enzymes.     

近江牡蛎糖胺聚糖的酶解提取及其抗肿瘤活性研究

探讨酶解法提取近江牡蛎糖胺聚糖(SG1)的务件,结果表明:先用枯草杆菌中性蛋白酶1.0%(质量分数),pH7.0,50℃酶解5 h,再加胰蛋白酶1.0%(质量分数),pH7.8,50℃酶解5 h效果最佳.粗提物SG1的得率为2.40%,总糖胺聚糖含量为13.6%,总糖含量为61.3%.采用四氮唑蓝还原法(MTT法)研究粗提物SG1对人宫颈癌细胞(Hela细胞)的体外抗肿瘤活性,结果显示:500μg/mL剂量组与600μg/mL剂量组48h时的抑制率分别为43.1%(P<0.05),55.8%(P<0.05),近江牡蛎糖胺聚糖粗提物SG1具有较明显的抗肿瘤活性,存在一定的量效关系.     

Quantification of Factors Which Influence Nisin's Inhibition of CIostridium botulinum 56A in a Model Food System

We modeled nisin's anticlostridial activity and assessed the antagonistic or potentiating influences of food ingredients. The model systems contained yeast extract, proteose peptone, and glucose; were supplemented with protein (0.075, 0.75, 7.5% w/v), phospholipid (0.075, 0.75, 7.5% w/v), or soluble starch (5, 17.5, 30% w/v); and were adjusted to pH 5.5, 6.0, or 6.5. Samples inoculated with 10⁴/mL spores were incubated at 15, 25, or 35°C. Statistical analysis developed an equation (r²= 0.76) that modeled the response and identified temperature as the most significant (α 0.001) variable. Nisin lost effectiveness with increasing temperature. Nisin concentration had significant positive and phospholipid negative, linear effects. Many interactive effects were significant (α 0.20). Nisin inhibited C. botulinum until its residual level dropped below a threshold, which decreased from 154 IU/mL at 35°C to 12 IU/mL at 15°C.     

Preparation and Partial Characterization of Eggshell Calcium Chloride

To minimize eggshell waste, calcium in eggshells was extracted as calcium chloride using 4% (w/v) HCl solution for an extraction period of 3 hs with the ratio of eggshell to HCl being 1:15 (w/v). After hydrolysis, the residues were removed by centrifugation at 1774 × g for 10 min, and the solution was heated to 110–115°C until dried, this gave an eggshell calcium chloride at a yield of 87.38% (w/w). The calcium chloride powder in this study was composed of 0.3% protein and 94.37% ash, with pH 5.27 and showed high solubility. It contained minute amount of heavy metal constituents within the specification of the Thai Food Act. X-ray diffraction analysis indicated that eggshell calcium chloride powder thus prepared was composed mainly of CaCl₂.2H₂O. The eggshell CaCl₂ was also tested for its functional property as a firming agent in canned rambutan. The results showed that both eggshell and commercial calcium chloride gave a firm texture to canned rambutan, therefore eggshell CaCl₂ can be prepared and used as food processing aids.     

基于高灵敏度荧光衍生剂的痕量维生素C液相检测方法建立

利用1.0 g/L 6-羟基-2,4,5-三氨基嘧啶作为荧光衍生剂,与水溶液中维生素C在pH为6.5±0.5反应条件下,40 ℃衍生反应30 min生成具有强荧光性的衍生产物。试验中对维生素C提取条件,衍生条件,色谱条件进行探索性研究及优化。在使用pH=4.0乙酸铵缓冲液(v)+乙腈(v)+甲醇(v)=80+15+5作为流动相的色谱条件下,该衍生物色谱行为稳定,并产生很强的荧光信号。配合高效液相色谱-荧光检测器对其含量进行检测。该方法检测维生素C具有检测结果准确,回收率为90.9%~96.7%,实验数据稳定RSD≤2%,灵敏度高方法检出限0.2 μg/g,检测线性范围0.05~500 μg/g,相关性系数良好,y=93322x-1837.8,R2=0.9999,实验操作简便,无需重复制备空白样品操作等特点,更适合实验室批量检测任务。并对6-羟基-2,4,5-三氨基嘧啶作为荧光衍生剂的使用提供一定的参考。