Effect of calcium on the physical properties of stirred probiotic yogurt

The effect of calcium on the viscosity, firmness, and smoothness, as determined by extent of nodulation, of stirred probiotic yogurt produced by bacterial fermentation was investigated. Standardized milk for yogurt manufacture was prepared, and calcium was added or removed from the system. Calcium was added as Ca²⁺ in the form of CaCl₂ (up to 13.6 mM) or nonionic calcium as Gadocal-K (calcium potassium citrate; up to 49.8 mM). Calcium was removed by chelating with sodium citrate (up to 16 mM) or by cation exchange with Amberlite IR-120 plus (sodium form) resin (up to 10 g/L). Calcium chloride and sodium citrate were added either before or after heat treatment of milk, and nonionic calcium was added before heat treatment. Calcium removal by ion exchange was performed before heat treatment. Neither Ca²⁺ addition nor removal by chelation with citrate resulted in stirred yogurt with viscosity, firmness, and smoothness superior to those of the control yogurt, whereas addition of 49.8 mM nonionic calcium and removal of calcium (5.6 mM or ∼10% of total calcium) by cation exchange improved the firmness and viscosity without affecting yogurt smoothness. The study identified Gadocal-K as a possible source of calcium fortification of stirred yogurt without loss of texture.     

Fat free plain set yogurts fortified with various minerals

Seven different minerals (iron, magnesium, zinc, manganese, molybdenum, chromium and selenium) were incorporated separately into the yogurt mixes at 25% of their recommended dietary allowances of 15 mg, 420 mg, 15 mg, 5 mg, 200 μg, 200 μg, 70 μg, respectively. The various attributes studied on the yogurts were viscosity, syneresis, color/lightness (L*), body and texture, appearance and flavor. No significant (P>0.05) difference was observed for viscosity of the yogurts fortified with minerals when compared to the control. Yogurts fortified with iron, selenium and magnesium had better water-holding capacities compared to the control. No significant (P>0.05) differences were observed for flavor and appearance scores of the yogurts fortified with the minerals compared to the control. Fortification of yogurts with these minerals can be accomplished without adversely affecting product characteristics.     

蛋白质强化对搅拌型酸奶品质特性的影响

为了研究蛋白质强化对搅拌型酸奶品质特性的影响,以脱脂奶粉(SMP)和乳清浓缩蛋白-80(WPC-80)作为蛋白源,研究了强化不同种类及不同含量(2.7%、3.1%、3.5%、3.9%)的蛋白质强化对搅拌型酸奶感官品质、黏度和持水性的影响。结果表明:用SMP和WPC-80强化原料乳的蛋白质均可提高搅拌型酸奶的感官品质、黏度和持水性;比较同种蛋白源、不同蛋白质强化水平制得的搅拌型酸奶,其组织状态变化明显,风味稍有变化,色泽保持不变;酸奶的黏度和持水性都随蛋白质水平的上升而显著提高。SMP强化蛋白质含量至2.7%时,酸奶的感官品质最好;WPC-80含量则在3.5%时,酸奶的感官品质最好。同一蛋白质水平、不同强化蛋白相比较,WPC-80强化酸奶比SMP有更好的感官品质和更高的持水性,而SMP强化则得到更高的黏度值;从感官评定的黏稠度得分和测得的黏度值对比得出,搅拌型酸奶的黏度并不是越高越好,最佳黏度值在537～712mPa.s之间。实验中搅拌型酸奶的最佳蛋白强化配方为WPC-80强化蛋白质含量3.5%。     

Effect of calcium and vitamin D2 fortification on quality characteristics of dahi

Two levels (500 and 600 ppm) of calcium (calcium phosphate and calcium citrate) along with vitamin D₂ (600 IU/L) were fortified in milk for dahi preparation. pH, water‐holding capacity and syneresis of fortified dahi were not affected significantly (P > 0.05). However, acetaldehyde content decreased and setting time increased upon fortification. Microbial count significantly (P < 0.05) decreased in calcium phosphate‐fortified dahi, whereas no difference was observed in calcium citrate‐fortified dahi. Firmness and viscosity decreased in calcium phosphate‐fortified dahi, whereas it increased in calcium citrate‐fortified dahi as compared to control. All dahi samples showed good sensory acceptability.     

Effect of bamboo salt on the physicochemical properties of meat emulsion systems

This study was conducted to determine the effects of various bamboo salts on meat batter. To accomplish this, three different batters were prepared and compared: CON, which was prepared with NaCl, BS-2, which was prepared with bamboo salt that was baked twice, BS-9, which was prepared with bamboo salt that was baked nine times. The pH of both the uncooked and cooked BS-2 and BS-9 was higher than that of the CON (P < 0.05). The emulsion stability, cooking yield, water holding capacity (WHC) and apparent viscosity of BS-2 and BS-9 were higher than those of CON. The correlation coefficient between the viscosity value and WHC was high and positive (R² = 0.672). The hardness of all treatments was significantly increased with increased cooking temperature (P < 0.05). The hardness, gumminess and chewiness of CON were higher than that of BS-9 and BS-2. The overall acceptability score between CON and BS-9 was significantly different (P < 0.05). The bamboo salts effectively improved the physicochemical properties of the meat batter.     

Preliminary observations on the effects of milk fortification and heating on microstructure and physical properties of stirred yogurt

The aim of this work was to study how milk fortification and heating affect yogurt microstructure (micellar characteristics, protein network) and physical properties (viscosity, water-holding capacity (WHC), and graininess). Milk was fortified with skim milk powder (control), whey protein concentrate (WPC), caseinate, or a mixture of caseinate and whey protein. Two heat treatments were applied, giving average whey protein denaturation levels of 58% and 77%. For caseinate-enriched yogurts, the heating effect was negligible. When milk was enriched with WPC, heating led to a high level of cross-linking within the gel network. Heating increased yogurt viscosity and WHC, but also graininess. When milk was fortified with a blend of WPC and caseinate giving a whey protein-to-casein ratio of 0.20, the yogurt viscosity was greatly improved, while graininess was kept low. The results show a relationship between micelle solvation and yogurt microstructure, as well as micelle size in milk base and yogurt graininess.     

Changes in proteasome activity during postmortem aging of bovine muscle

The effects of adding commercial-grade and eggshell calcium lactate on the microbiological and physicochemical properties of Nhams (Thai-style fermented pork sausage) were studied. The Nham calcium levels were 150, 300 and 450 mg/100 g. Compared to controls (no added calcium), calcium fortification did not affect the number of lactic acid bacteria or the colour value. The shear force of Nhams fortified with eggshell calcium lactate decreased (P<0.05) from 32.2 N in the controls to 19.5-22.8 N in Nhams fortified with eggshell calcium lactate. However, Nhams fortified with commercial calcium lactate had the same shear force as the controls. Sensory scores of sour taste, flavour and overall acceptance were not different between the control and calcium-fortified Nhams at a calcium level of 150 mg/100 g.     

Stability of potassium iodide and omega-3 fatty acids in fortified freshwater fish emulsion sausage

Oxidative stability of emulsion sausages prepared from African walking catfish (AF: Clarias gariepinus) and rohu (RH: Labeo rohita) fortified with three levels of the refined tuna oil (2%, 6%, and 10%) with 150 μg KI/100 g sample and without KI was investigated. The control was prepared using 20% soybean oil and without KI. Samples were vacuum-packed and stored at 4 °C. Iodine content decreased approximately 14% after cooking and remained constant throughout storage. Sausages fortified with tuna oil showed higher level of n-3 (eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)), but lower level of n-6 fatty acids (P<0.05) than the control. The ratio of n-6 to n-3 fatty acids of all samples decreased with an increase of tuna oil addition and was stable throughout 4 weeks of storage. Degradation of linoleic (LA) and linolenic acid (LNA) mainly occurred in the samples added 2% tuna oil whereas samples fortified with higher tuna oil (6-10%) exhibited higher loss of EPA and DHA. Hydroperoxide (HPV) and thiobarbituric reactive substances (TBARS) values were increased as addition level of tuna oil increased. Textural properties were not affected during storage at 4 °C for up to 4 weeks (P<0.05). Based on lipid stability results, 2% fortification of the refined tuna oil was recommended for emulsion sausage prepared from both species. Addition of 150 μg KI/100 g had no effect on lipid oxidation of fish sausages (P<0.05).     

Evaluation of volatile compounds and free fatty acids in set types yogurts made of ewes’, goats’ milk and their mixture using two different commercial starter cultures during refrigerated storage

Six different types of yogurt were manufactured from Damascus goat milk, Awassi ewe milk and a mixture of equal portions of the 2 species of milk using 2 types of commercial yogurt cultures (CH-1 and YF-3331). Yogurts were chemically analysed at 1, 7, 14 and 21 days of storage. Results showed that cultures significantly affected acetaldehyde (P < 0.05), acetone (P < 0.05) and diacetyl (P < 0.001) contents. Type of milk significantly influenced acetaldehyde (P < 0.05), diacetyl (P < 0.001), acetoin (P < 0.001) and ethanol (P < 0.05) levels. Significant variations occurred in acetaldehyde (P < 0.001) and acetoin (P < 0.05) contents during the storage. Short-chain free fatty acids were the highest in ewes’ milk yogurt made with culture YF-3331, and increased during storage, while the levels of medium-chain free fatty acids, except for decanoic acid, were unchanged and the amount of long-chain free fatty acids decreased during storage. Cultures used and types of milk had no effect on long-chain free fatty acids in yogurts.     

Interactions of dietary fibre and omega-3-rich oil with protein in surimi gels developed with salt substitute

Most Western populations have insufficient intake of fibre and ω-3 polyunsaturated fatty acids (PUFAs), while sodium intake greatly exceeds the recommended maximum. Surimi seafood is not currently fortified with these nutraceutical ingredients. Alaska pollock surimi seafood was developed with salt substitute and fortified with either 6 g/100 g of fibre or 10 g/100 g of ω-3 oil (flax:algae:menhaden, 8:1:1) or fibre + ω-3 oil (6 g/100 g of fibre + 10 g/100 g of ω-3 oil). The objective was to determine effects of the dietary fortification on physicochemical properties of surimi. Fortification with either dietary fibre or ω-3 oil alone or in combination enhanced (P < 0.05) rheological and textural characteristics. The combined fortification had a synergistic effect on rheological properties. This indicates greater gelation of surimi in the presence of fibre + ω-3 oil, suggesting their interaction with surimi myofibrillar proteins. Fibre results in protein dehydration increasing protein concentration; while oil is immobilised by protein filling void spaces in the gel matrix. Differential scanning calorimetry showed that fibre and ω-3 oil did not interfere with normal denaturation of surimi proteins. Colour properties were only slightly affected (P < 0.05). Fortification of surimi with fibre and ω-3 oil resulted in a quality product that could be useful in developing surimi products with nutritional benefits.     

Effect of different gas stunning methods on Manchega suckling lamb meat packed under different modified atmospheres

Forty-nine Manchega breed male suckling lambs were used in this experiment. The effect of CO₂ concentration and exposure time at stunning [80% CO₂ for 90 s (G1); 90% CO₂ for 90 s (G2); 90% CO₂ for 60 s (G3); 80% CO₂ for 60 s (G4)] plus an electrically stunned control group (G5) was assessed for pH, colour (L^∗, a^∗, b^∗, C^∗ and h^∗), water holding capacity (WHC), drip loss (DL), cooking loss (CL) and shear force (SF) in samples packed under two different types of modified atmospheres (MA: MA A: 70%O₂ + 30%CO₂; MA B: 69.3%N₂ + 30%CO₂ + 0.7%CO) at 7, 14 and 21 d post-packaging. The lowest pH was found in G4 and in G5. The highest WHC and the lowest CL were found in G2 and G3 groups (P < 0.05). Modified atmospheres did not affect on pH, WHC, CL and DL, although a significant effect (P < 0.001) on colour was found at all the analysis times. Both the type of stunning and the modified atmosphere affected SF values.     

温度对酸乳中乳酸菌胞外多糖作用机制的研究

重点探讨了不同发酵温度下酸乳发酵产生的胞外多糖含量变化以及添加不同来源的胞外多糖对酸乳流变学特性的作用,结果表明:37℃条件下发酵所得酸乳多糖含量最高,达到461.4mg/mL,43℃条件下酸乳多糖含量最低,仅为247.6mg/mL。酸乳产生的内源性胞外多糖表现在产品特性上,其表观黏度及剪切应力随时间的变化都明显(P<0.05)高于外源添加胞外多糖的酸乳。表观黏度随剪切时间的变化曲线符合对数函数y=kLn(x)+b(内、外源R2分别为0.9527、0.9015)的变化规律。此外,酸乳经过发酵产生内源性胞外多糖后,其持水力(WHC)较添加外源性胞外多糖的酸乳高出26%,胶体脱水收缩作用敏感性(STS)较添加外源性胞外多糖的酸乳低46%。这说明低温有利于乳酸菌胞外多糖形成,且内源性胞外多糖酸乳的表观黏度大、持水力高。     

Freshness assessment of ray fish stored in ice by biochemical,chemical and physical methods

Ray fish were caught, filleted, and stored in ice. Fillets were analysed for 18 days to determine the chemical, biochemical and physical changes and their relation to the muscle eating quality. Trimethylamine (TMA-N), total volatile bases (TVB-N), ATP content and breakdown products, K value, pH, texture, water-holding capacity (WHC) and colour changes were monitored. At the beginning of the study, the ray fish muscle showed a low concentration of ATP and a high value of inosine 5′-monophosphate (IMP). Regarding to the signs of freshness and deterioration, K value presented an exponential increase (r2 = 0.95) with an initial value of 4.7% and a final value of 47.5%. Furthermore, the TBV-N and TMA-N significantly increased (P < 0.05) during the storage in ice. As for the physical analysis whereas the texture changed (P < 0.05); pH and the WHC were not affected (P < 0.05). The overall results of this study indicated that the edible quality of ray fish muscle was maintained during at least 15 days of ice storage.     

CO2 stunning procedure on Manchego light lambs: Effect on meat quality

This study examined the effect of different gas stunning methods (concentration of CO₂/time of exposure (G1: 80%90s; G2: 90%90s; G3: 90%60s; G4: 80%60s) on the initial meat quality of Manchego breed light lambs (25 kg live weight) and at 7 days post-mortem, assessed by pH, colour coordinates, water holding capacity (WHC), cooking loss (CL), drip loss (DL) shear force (SF) and lipid oxidation. An electrically stunned control group (G5) was used. Stunning method had a significant effect on pH values (P < 0.001) as well as on pH decline (P < 0.01). The lowest pH was found at 24 h post-slaughter in G1 and the highest one on G5. The greatest drop in pH (pH₀–pH₂₄) was found in G1 and G5 while the smallest in G3. In general values of colour coordinates, WHC and DL were similar in all groups. Stunning method affected CL (P < 0.001) at 7 days post-slaughter, with the lowest values being found in G1. Significant differences among groups were found (P < 0.05) in SF values at both post-mortem times, with less tender meat in groups stunned with 80% CO₂, especially in G1. A significant effect (P < 0.001) due to the type of stunning was found at 24 h on lipid oxidation, with the highest value in G5. After ageing this parameter was lowest (P < 0.05) in G1 and G4.     

Survival of Lactobacillus acidophilus and Bifidobacterium animalis ssp. lactis in stirred fruit yogurts

The effect of commercial fruit preparations (mango, mixed berry, passion fruit and strawberry) on the viability of probiotic bacteria, Lactobacillus acidophilus LAFTI^® L10 and Bifidobacterium animalis ssp. lactis LAFTI^® B94 in stirred yogurts during storage (35 days) at refrigerated temperature (4 °C) was evaluated. The results showed that addition of either 5 or 10 g/100 g fruit preparations had no significant (p>0.05) effect on the viability of the two probiotic strains except on L. acidophilus LAFTI L10 yogurt with 10 g/100 g passion fruit or mixed berry. After the addition of fruit preparation, 96% of the yogurts incorporated with fruit preparation did not exhibit a greater loss in the viability of probiotic bacteria compared to plain yogurt during the storage period. A correlation between the post-storage pH in yogurts and the survival of probiotic bacteria was observed. All the yogurts, however, contained the recommended levels of (10⁶-10⁷ cfu/g) probiotic bacteria at the end of 35-day shelf life.     

Effects of feeding a single or sequence of beta-adrenergic agonists on cull cow meat quality

Sixty cull cows were implanted and assigned to four treatments: C = concentrate ration only; RH = supplemented with ractopmaine-HCl (8.33 mg/kg of feed) for 25 d; ZH = supplemented with zilpaterol-HCl (ZH) (200 mg head ^– 1d^– 1) for the last 20 d; and RH + ZH = supplemented with RH for 25 d followed by ZH for 20 d. All cows were fed a concentrate ration for 74 d. Infraspinatus steaks from cows supplemented with RH and/or ZH had lower (P < 0.05) shear force than steaks from C cows. Longissimus (LM) steaks from the 6–8th rib section of ZH and RH + ZH cows had decreased (P < 0.0001) desmin degradation at 10 and 21 d postmortem compared to steaks from C and RH cows. Collagen solubility of the LM was increased (P < 0.05) by ZH and RH + ZH compared to C. There were no treatment differences in 12th rib LM tenderness when enhanced with calcium lactate. Color and sensory traits of meat from RH + ZH cows were not different from C but flavor intensity was greater and off-flavor less than for C cows.     

The effect of ractopamine hydrochloride (Paylean) on lean carcass yields and pork quality characteristics of heavy pigs fed normal and amino acid fortified diets

Effects of ractopamine hydrochloride (RAC) on carcass parameters in heavy weight (133.24 ± 8.07 kg) finishing pigs (n = 278) given amino acid fortified (AA) or 16% crude protein (CP) diets were evaluated. A total of seven experimental diets were formulated; RAC was added at 0, 5 and 20 ppm to the 16% CP diets (CP0, CP5 and CP20, respectively) and at 0, 5, 10 and 20 ppm to the AA fortified diets (AA0, AA5, AA10 and AA20, respectively). Carcass, tenderloin, and ham weights were heavier (P < 0.05) for RAC AA diets vs. AA0. Loin weight was heavier (P < 0.05) for AA20 vs. AA0 and CP20 vs. CP0. No differences (P > 0.05) were observed for color or firmness scores. Carcass muscle score, ham weight and protein% were greater (P < 0.05) for RAC diets. Moisture was greater (P < 0.05) and fat was lower (P < 0.05) for AA5 and AA20 vs. AA0 and CP5 and CP20 vs. CP0. Feeding RAC to late finishing swine increases carcass yields and protein% with lower fat% for pigs weighing up to 136 kg.     

Postmortem changes in cazon fish muscle stored on ice

The biochemical, chemical and physical postmortem changes and their relation to the cazon muscle eating quality were studied during an 18 day storage period at 0 °C (ice). Content of ATP and breakdown products, K value, pH, trimethylamine (TMA-N), total volatile bases (TVB-N), water-holding capacity (WHC), colour and texture changes were examined. At the beginning of the study, the cazon muscle showed a low concentration of ATP and a high value of IMP. Regarding to the signs of freshness and deterioration, K value presented a linear increase (r² = 0.97) with an initial value of 1.05% and a final value of 58.9%. The TBV-N and TMA-N significantly increased (P < 0.05). As for the physical analysis whereas the pH and the WHC changed (P < 0.05); texture was not affected (P < 0.05). The overall results of this study indicated that the edible quality of cazon fish muscle was maintained during at least 18 days of ice storage.     

Sensory characteristics and iron dialyzability of gluten-free bread fortified with iron

The objectives of the present study were (a) to produce gluten-free bread, fortified with iron (GFB-Fe), using selected iron compounds (ferric pyrophosphate, ferric pyrophosphate with emulsifiers, NaFeEDTA, electrolytic iron, ferrous gluconate, ferrous lactate and ferrous sulphate) (b) to test sensory characteristics of the GFB-Fe (feel-mouth texture, crumb colour, aroma and taste) (c) to compare iron dialyzability of various iron compounds in GFB-Fe. The most acceptable products were those fortified with ferric pyrophosphate with emulsifiers and ferric pyrophosphate. Ferrous dialyzable iron (ferrous iron with molecular weight lower than 8000 Da, an index for prediction of iron bioavailability) was measured under simulated gastrointestinal conditions. Ferrous dialyzable iron in GFB-Fe fortified with ferric pyrophosphate with emulsifiers, NaFeEDTA, ferrous bis-glycinate, ferrous gluconate or ferrous sulphate was higher than that in GFB-Fe fortified with electrolytic iron, ferrous lactate or ferric pyrophosphate (P < 0.05). These results are promising for the development of GFB-Fe products in the future.     

Characteristics of reduced fat milks as influenced by the incorporation of folic acid

Folic acid plays an important role in the prevention of neural tube defects (e.g., spina bifida and anencephaly), heart defects, facial clefts, urinary abnormalities, and limb deficiencies. Milk and milk products serve as a potential source for folic acid fortification because of the presence of folate-binding proteins that seem to be involved in folate bioavailability. Although milk is not a good source of folic acid, fortification could help in the prevention of the above-mentioned defects. The objective of this study was to examine the physicochemical characteristics of reduced fat milks fortified with folic acid. Reduced fat milks were prepared using 25, 50, 75, and 100% of the recommended dietary allowance of 400 μg of folic acid. Treatments included addition of folic acid at these levels before and after pasteurization. Color, pH, fat, protein, viscosity, folic acid concentration, folate-binding protein concentration, folate-binding protein profile, standard plate count, and coliform counts were determined on d 1, 7, 14, and 21. A consumer acceptability test was conducted on d 7. Data from the consumer panel were analyzed using ANOVA (PROC GLM) with means separation to determine the differences among treatments. Data obtained from the color, pH, fat, protein, viscosity, folic acid concentration, folate-binding protein concentration, standard plate count, and coliform counts were analyzed using the GLM with a repeated measure in time. Significant differences were determined at P < 0.05 using Tukey's Studentized Range Test. There were no differences in the electrophoretic mobility of folate-binding protein in the samples. The concentration of folic acid was significantly higher in reduced fat milks fortified with folic acid after pasteurization compared with the treatments in which folic acid was added before pasteurization. The consumer panelists did not find any significant differences in flavor, appearance, or texture of folic acid fortified reduced fat milks compared with that of the control. Fortification of reduced fat milks with folic acid can be accomplished without adversely affecting the product characteristics.