Fermentation and Properties of Calcium-fortified Soy Milk Yogurt

Calcium-fortified soy milk yogurt containing 190 mg calcium/100g was produced and evaluated for textural and microstructural properties. The soy milk base contained 10% full fat soy flour, 2.25% soy protein isolate, 2.75% high fructose corn syrup, 1.55% calcium lactogluconate, and 1.25% potassium citrate. The mixture was heated 5 min at 80°C, cooled to 42°C, and inoculated with yogurt cultures. Calcium-fortified soy milk required a higher rate of inoculation (5%) than non-fortified soy milk (2.5%) and had higher titratable acidity and more syneresis. Calciumfortified soy milk yogurts showed comparable gel strength with that of commercial regular yogurt. Gels from nonfortified soy milk yogurts were hard and brittle. Addition of calcium did not significantly affect microstructure of the yogurts.     

Effects of Calcium Addition on Stability and Sensory Properties of Soy Beverage

Pasteurized or thermally processed soy beverages (6% soy solids) were fortified to a comparable level of cow's milk with 25 mM (or 30 mM) calcium using mixtures of calcium citrate and tricalcium phosphate. These fortified pasteurized products had acceptable sensory properties. Addition of these calcium salts did not adversely affect protein stability of the beverage. Calcium citrate addition caused a decrease in beverage pH and viscosity. Thermally processed (still retort and agitort) canned beverages containing calcium salts were stable for 6 months when stored at 1°C or at room temperature.     

Commercial Mineral Enhanced Dairy By‐Products as Sodium Replacers,Antioxidants and Calcium Fortifiers in Sausages

Sausages are perceived as high in Na and with a too high Na:K ratio. Frankfurter type sausages are regarded as important contributors of sodium in the diet and thereby of health risks. Surplus products from the dairy industry are various mineral powders enriched in either potassium, calcium, or phosphate and include various amounts of lactose. Sausages were produced at 3 sodium levels (equivalent to 13, 15, and 17 g NaCl/kg sausage) using 4 different milk ingredients (a dried skimmed milk powder, a calcium enriched milk powder, a potassium enriched powder, and a lactose enriched powder). The sausages with added calcium and potassium enriched milk powders resulted in the hardest sausages when compared at the same sodium level. Milk mineral addition also produced whiter and less red sausages. No effect on rancidity after 6 wk at chill (4 °C) storage was observed by adding milk minerals, when compared with adding dried skimmed milk powder. A significant advantage of using these milk minerals in sausages is that the Na:K ratio can be reduced from an unhealthy (in this study 36) to a far healthier ratio ( ? 2) with limited or no taste changes. High additions of milk calcium (6 g/kg), where Ca‐phosphates prevail, added as milk mineral, had no influence on sensory bitterness or aftertaste as typically observed for CaCl₂ additions. Ca additions to sausages are presently presumed to be an advantage with respect to human nutrition.     

Characterization of Isoflavones in Membrane-processed Soy Protein Concentrate

ABSTRACT: Aqueous soy flour solutions (5% w/w) were treated for 3 h at 45 to 50 °C with Crystalzyme®, without enzyme at 45 to 50 °C, or blanched at 80 °C. Solutions were ultra‐ and dia‐filtered to produce membrane soy concentrates (MSC). Total isoflavones of MSCs were 3.02 mg/g, 3.12 mg/g, or 3.42 mg/g, respectively, on a dry weight basis. Membrane processing contributed to approximately 18, 15, or 8% decreases, respectively, in total isoflavones of MSCs compared with soy flour (3.71mg/g). This represents at least an 82% recovery. There was no significant difference in total isoflavone content in any MSC, however the profile of isoflavones as glucosides or aglycones changed with treatment conditions.     

Production of soy yogurt enriched with glyceollins

Soy milk was prepared from regular soybean (M1), soybean germinated for 3 days at 25°C (M2), and soybean germinated under fungal infection (M3). Rhizopus microsporus var. oligosporus ATCC 22959 was used as the elicitor for glyceollin production. Each soy milk was fermented with Streptococcus infantarius 12 and Weissella sp. 4 (1:5, v/v) for 12 h at 37°C. Significant induction of glyceollins was confirmed only in M3 soy milk and glyceollins maintained stably during 12 h fermentation period. The concentration of glyceollins in M3 yogurt was 2,400.4±83 and 2,525.2±158 μg/g dry matter (d.m.) at 0 and 12 h, respectively. The amount of daidzein was significantly higher in M3 yogurt (635.1±21) than that of M1 (417±11) and M2 (545±17 μg/g d.m.) yogurt in 12 h (p<0.05). M2 yogurt had the highest amount of genistein (695.3±17) followed by M3 (634.5±26) and M1 (612.5±14 μg/g d.m.) yogurt. M3 soy yogurt also showed the highest content of total phenolic compounds (5.37 mg/g) and antioxidant activity. The results indicated that functional soy yogurt can be prepared from soybean enriched with glyceollins.     

Calcium Fortification of Soy Milk with Calcium-Lecithin Liposome System

Calcium ion was enveloped with a membrane system before addition to soy protein to prevent soy protein from being coagulated and precipitated by calcium ion. Soy lecithin was first sonicated in calcium salt solution to envelop the calcium ion with a liposomal structure composed of lecithin. Then, the calcium-lecithin liposomes were added to soy protein solution. Precipitation and coagulation were not observed in this soy protein-lecithin liposome system containing 60 mM Ca²⁺. By this method, it was possible to prepare calcium fortified soy milk containing more calcium (120 mg/100g) than in cow's milk. These results suggest that this calcium-lecithin liposome system is useful for calcium fortification of soy milk.     

Mineral and casein equilibria in milk: effects of added salts and calcium-chelating agents

We have investigated the effects of adding a range of mineral salts and calcium-chelating agents on the distribution of casein and minerals between the non-pelleted and pelleted phases of milk obtained upon centrifugation at 78000 g for 90 min. Adding CaCl2 or mixtures of NaH2PO4 and Na2HPO4 to reconstituted skim milk (90 g milk solids/kg) at pH 6.65 increased both pelleted casein and pelleted calcium phosphate. Opposite effects were obtained by adding citrate or EDTA. The change in pelleted calcium phosphate was not simply related to casein release from the micelle. Upon adding 5 mmol EDTA/kg milk, 20% of the pelleted Ca, 22% of the pelleted phosphate and 5% of the micellar casein were removed. Increasing the concentration of EDTA to 10 mmol/kg milk decreased the pelleted Ca by 44% and the pelleted phosphate by 46%, and caused 30% of the micellar casein to be released. The effects of adding phosphate, citrate or EDTA at pH 6.65, followed by the addition of CaCl2, demonstrated the reversibility of the dissolution and formation of the micellar calcium phosphate. There were limits to this reversibility that were related to the amount of colloidal calcium phosphate removed from the casein micelles. Adding CaCl2 to milk containing > or = 20 mmol EDTA or > or = 30 mmol citrate/kg milk did not result in complete reformation of casein micelles. Light-scattering experiments confirmed that the dissolution of moderate amounts of colloidal calcium phosphate had little effect on micellar size and were reversible, while the dissolution of larger amounts of colloidal calcium phosphate resulted in large reductions in micellar size and was irreversible.     

Nutritional,antioxidant, and antimicrobial assessment of carrot powder and its application as a functional ingredient in probiotic soft cheese

Carrots (the main source of carotenoids) have multiple nutritional and health benefits. The objectives of this study were to evaluate the compositional, antioxidant, and antimicrobial properties of carrot powder and to examine its effect on the sensory characteristics, chemical properties, and microbial viability of probiotic soft cheese at a rate of 0.2, 0.4, and 0.6%. The carrot was turned into powder before being analyzed and incorporated as an ingredient in making probiotic soft cheese. Probiotic soft cheese was made from buffalo milk. The buffalo milk (～6.9% fat, 4.4% protein, 9.2% milk solids not fat, and 0.7% ash) was pasteurized at 75 ± 1°C for 5 min and cooled to 40–42°C. The milk was then divided into 4 aliquots. Sodium chloride (local market, Assiut, Egypt) was added at a ratio of 5% followed by starter cultures. The carrot powder (4.5% moisture, 4.8% ash, 2.7% fat, 8.2% protein, 11.9% fibers, and 72.3% carbohydrate) was added at a rate of 0.2, 0.4, and 0.6%, followed by addition of 0.02 g/kg rennet. The cheese was cut again into cubes, pickled in jars filled with whey, and stored for 28 d at 6 ± 1°C. The results of this study illustrated the nutritional and antioxidant properties of carrot powder. Incorporation of carrot powder in probiotic soft cheese affected the moisture and salt content at 0 d. The total bacteria count decreased from 7.5 to 7.3 log cfu/g in the cheese when carrot powder was used at a rate of 0.6%. The reduction of total bacteria count was noticed during the 28 d of storage by adding carrot powder. Furthermore, lactic acid bacteria and Bifidobacterium longum counts elevated with adding carrot powder during the 28 d of storage.     

Antilisterial Activity of Hops Beta Acids in Broth with or Without Other Antimicrobials

ABSTRACT: Hops beta acids (HBA) are parts of hops flowers used to preserve wort and provide flavor in beer, and are reported as having antimicrobial properties. This study evaluated the antilisterial activity of HBA alone or in combination with other known antimicrobials in a culture broth medium. Listeria monocytogenes (10‐strain mixture) was inoculated (2.6 to 2.8 log CFU/mL) into tryptic soy broth supplemented with 0.6% yeast extract (TSBYE) without (control) or with HBA (0.5 to 5.0 μg/mL), potassium lactate (1.0%), sodium diacetate (0.25%), or acetic acid (0.1%), alone or in combination with HBA (0.5 to 3.0 μg/mL). Survival/growth of the pathogen during storage at 4 °C (35 d), 10 °C (20 d), or 25 °C (2 d) was periodically monitored by spiral plating onto tryptic soy agar plus 0.6% yeast extract. As expected, TSBYE without antimicrobials (control) supported rapid pathogen growth with growth rates of 0.40, 2.88, and 9.58 log CFU/mL/d at 4, 10, and 25 °C, respectively; corresponding Y_end values exceeded 9.0 log CFU/mL at 35, 20, and 2 d storage. HBA used alone (1.0 to 5.0 μg/mL) inhibited growth of L. monocytogenes at all 3 temperatures, with inhibition being more pronounced at higher concentrations and at the lower storage temperature (4 °C). The antilisterial activity of HBA (0.5 to 3.0 μg/mL) was enhanced when combined with sodium diacetate, acetic acid, or potassium lactate, achieving complete inhibition at 4 °C when 3.0 μg/mL HBA were used in combination with each of the above antimicrobials. Overall, HBA exhibited promising antilisterial activity in a broth medium and further studies are needed to investigate its potential antilisterial effects in food products.     

Chemical composition and nutritive value of spray dried permeate powder

Reconstituted skimmed milk (10% TS) was ultrafiltered, and the permeate was concentrated threefold by reverse osmosis and then spray dried at different temperatures (145–195° C). The drying conditions had no effect on the moisture content or the major constituents of permeate powder. The powder was mainly lactose (85%) with 6.35460% ash. A small percentage of the lactose in the permeate powder was present as a-lactose. Sodium, potassium and citrate were present in high concentrations nearly equivalent to their average percentage in skimmed milk. The calcium, magnesium and inorganic phosphorus contents of permeate powder were also determined. The thiamine, riboflavin and niacin contents of permeate powder averaged 0.445, 0.947 and 0.729 mg/100 g respectively. The drying temperatures had no effect on the vitamin contents of the powder. The permeate powder had average Fe, Zn, Mn and Cu contents of 94.7, 21.1, 3.1 and 9.5 Fg/100 g respectively.     

Chemical Treatment and Process Modification for Producing Improved Quick-Cooking Rice

Quick-cooking rice was produced by soaking raw, white, long grain rice in a 1% aqueous sodium citrate and calcium chloride solution (50:50) at 50°C for 15 min. The soaked sample was cooked in an autoclave at 121°C for 3 min and freeze-dried to 20% moisture followed by convective air-drying to a final moisture of 12%. Nutrient analysis of the rice chemically treated and dried by a combination of both methods contained maximum amounts of thiamin (2.0 μg/g), niacin (27.4 μg/g), and iron (25.1 μg/g). The rehydrated sample, prepared by boiling the rice in water at 100°C for 5 min, received high sensory scores.     

Effect of heat treatment on activity of staphylococcal enterotoxins of type A,B, and C in milk

Intoxication by staphylococcal enterotoxins (SE) is among the most common causes of food-poisoning outbreaks resulting from the consumption of raw milk or products made thereof. The aim of our study was to analyze the thermal stability of SE and evaluate the inactivation of SE types A, B, and C (SEA, SEB, SEC) by autoclaving at 100°C, 110°C, and 121°C. Milk samples were inoculated with 38 Staphylococcus aureus strains that possessed the ability to produce SEA, SEB, or SEC and incubated at 37°C for 24 h. This incubation was followed by heat treatment at 100°C, 110°C, or 121°C for 3 min. Samples were analyzed by Staph. aureus plate count method on Baird-Parker agar and specifically for the presence of SE. An enzyme-linked immunofluorescent assay (ELFA) on a MiniVIDAS analyzer (bioMérieux, Marcy l'Étoile, France) was used to detect SE, which were determined semi-quantitatively based on test values. The obtained results were analyzed by means of nonparametric statistical methods. All samples (100%; 38/38) were SE-positive before heat treatment, and the positivity rates decreased after heat treatment at 100°C, 110°C, and 121°C to 36.8% (14/38), 34.2% (13/38), and 31.6% (12/38), respectively. The rates of positive samples differed between SEA, SEB, and SEC producers: SEA was detected in the highest amounts both before and after heat treatment. The amount of SE (expressed as test values) decreased significantly after heat treatment. Comparing amounts of SE in positive and negative samples before and after heat treatment, we can conclude that the success of SE inactivation depends on the amount present before heat treatment. The highest amount of SE and the highest rate of SE-positive samples after all heat treatments were found in samples with strains producing SEA. For SEB and SEC, lower amounts of enterotoxin were present and were inactivated at 100°C. Although temperatures of 100°C, 110°C, and 121°C may inactivate SE in milk, the key measures in prevention of staphylococcal enterotoxicosis are avoiding initial contamination of milk by Staph. aureus, promoting consumption of heat-treated milk, and preventing disruption of the cold chain during milk production and processing.     

Characterisation of heat-set milk protein gels

Milk protein solutions [10% protein, 40/60 whey protein/casein ratio containing whey protein concentrate (WPC) and low-heat or high-heat milk protein concentrate (MPC)] containing fat (4% or 14%) and 70–80% water, form gels with interesting textural and functional properties if heated at high temperatures (90 °C, 15 min; 110 °C, 20 min) without stirring. Adjustment of pH before heating (HCl or glucono-δ-lactone) produces soft, spoonable gels at pH 6.25–6.6, but very firm, cuttable gels at pH 5.25–6.0. Gels made with low-heat MPC, WPC and low fat gave some syneresis; high-fat gels were slightly firmer than low-fat gels. Citrate markedly reduced gel firmness; adding calcium had little effect on firmness, but increased syneresis of low-heat MPC/WPC gels. The gels showed resistance to melting, and could be boiled or fried without flowing. Microstructural analysis indicated a network structure of casein micelles and fat globules interlinked by denatured whey proteins.     

High-pressure structuring of milk protein concentrate: Effect of pH and calcium

In this study, we investigated the effect of pH and calcium on the structural properties of gels created by high-pressure processing (HPP, 600 MPa, 5°C, 3 min) of milk protein concentrate (MPC, 12.5% protein). The pH level of the MPC was varied between 6.6 and 5.1 by adding glucono-δ-lactone (GDL), and the calcium content was varied from 24 to 36 mg of Ca/g of protein by adding calcium chloride. The rheological properties and microstructure of the pressure-treated MPC were assessed. The pressurization treatments and analytical testing were conducted in triplicate. Data were analyzed statistically using one-way ANOVA with Tukey's honestly significant difference post hoc tests. A pressurization time of 3 min was sufficient to induce gel formation in MPC at pH 6.6, so it was used throughout the study. Adjusting either pH or calcium affected the structure of the HPP-created milk protein gels, likely by influencing electrostatic interactions and shifting the calcium–phosphate balance. Gels were formed after pressurization of MPC at pH above 5.3, and increasing the pH from 5.3 to 6.6 resulted in stronger gels with higher values of elastic moduli (G′). At neutral pH (6.6), adding calcium to MPC further increased G′. Scanning electron microscopy showed that reducing pH or adding calcium resulted in more porous, aggregated microstructures. These findings demonstrate the potential of HPP to create a variety of structures using MPC, facilitating a new pathway from dairy protein ingredients to novel, gel-based, high-protein foods, such as puddings or on-the-go protein bars.     

Sodium Dodecyl Sulfate and Sulfite Improve Some Functional Properties of Soy Protein Concentrates

The effects of sodium dodecyl sulfate (SDS) and sodium sulfite were studied on dispersibility, water and oil absorption of soy protein concentrates from toasted soy flours. Dispersibility was improved from 6.2% to 65% by 0.5% SDS, 0.25% sodium sulfite at pH6, and 60°C. Water absorption was improved from 5.5 to 7 mL water/g concentrate by 0.5% SDS at pH 6 at 20°C. Oil absorption was improved from 4.1 to 5.9 mL oil/g concentrate by 0.5% SDS, 0.25% sodium sulfite at pH 6 and 20°C.     

Microbiology of a Ham-Type Product Made from Soy-Extended Cured Beef and Inoculated with Clostridium sporogenes PA3679

The microbiological stability of a new ham-type product made from soy-extended cured beef was examined under wholesale (2–4°C) and retail (5°C) refrigerated storage conditions, and during abuse-temperature holding for 24 and 48 hr at 24-25°C after inoculation with Closrridium sporogenes PA3679. No microbiological effects (P >0.05) could be attributed to the level of soy protein isolate in the injection brine (0, 5, 7.5 or 9%) on the basis of mesophilic, psychrotrophic, anaerobic and lactic bacterial counts. Samples held at 2-4°C did not exceed 10⁴ CFU/g after 4 wk for any bacterial type examined. Product shelf-life was > 3 wk at 5°C and 2 wk at 8–10°C. Inoculated PA3679 did not grow in the product during 24 or 48 hr simulated mishandling (24-2°C).     

STUDIES ON PRESERVATION OF SUGARCANE JUICE

ABSTRACT

The variety CoP 92226 was selected for preparing sugarcane juice beverage on the basis of yield and sensory attributes from eight promising varieties of sugarcane. Sugarcane juice beverage samples were prepared by pasteurizing the sugarcane juice at 70°C for 10 minutes and adding citric acid (40 mg/100 ml), ascorbic acid (40 mg/100 ml) and potassium metabisulphite (150 ppm). Samples of sugarcane juice beverage were stored at room (30±5°C) and refrigeration (4±2°C) temperature in pre-sterilized glass bottles and analyzed for physico-chemical, microbiological and sensory attributes at every 15 days interval for 90 days. The pH, total soluble solids and total sugars decreased, whereas, titratable acidity and reducing sugars increased significantly (P<0.01) during storage. An appreciable increase in total plate counts and yeast and mold counts were observed, however, no coliforms, were detected in sugarcane juice beverage during storage. The changes in different attributes were significantly (P<0.01) higher at room temperature as compared to refrigeration temperature. The sugarcane juice beverage having citric acid and potassium metabisulphite showed minimum changes in sensory qualities during storage, both at room and refrigeration temperature. An acceptable quality beverage of sugarcane juice with satisfactory storage stability for 90 days at room as well as refrigeration temperature could be prepared.     

Counteracting Recontamination of Pasteurized Milk by Methylated Soybean Protein

Methylated soy protein (MSP) was evaluated as an antimicrobial agent that can counteract the potential post-pasteurization contamination of milk during a 30-day cold storage (4 °C) or 24-h room temperature storage (25 °C) as compared to its native form (SP). SP and MSP were added to buffalo milk at 0.5% (w/v) after pasteurization and before storage. Milk microbiological and chemical analyses were carried out either directly to follow the spontaneous microbial contamination or after artificial contamination with three pathogens (Escherichia coli O157:H7, Listeria monocytogenes Scott A, and Salmonella enterica subsp. enterica serovar Enteritidis PT4). Supplementation of milk samples with MSP (0.5%) significantly (p?<?0.05) and considerably inhibited the levels of the spontaneously proliferating bacterial counts, i.e., total viable and Enterobacteriaceae counts were inhibited by about 2.5 log CFU mL^?1, while psychrotrophic and pseudomonads counts were inhibited by 1.8 and 1.6 log CFU mL^?1, respectively, after 16 days of preservation at 4 °C. Similar trend of effects were also produced after 12–18 h of milk storage at 25 °C. MSP (0.5%) nearly hindered the proliferation of the three inoculated pathogens in pasteurized milk during 16 days of storage at 4 °C or 12–18-h storage at 25 °C. Based on milk acidity, SDS–PAGE pattern, and microbiological analysis, it is concluded that supplementation with MSP (0.5%) can prolong the shelf life of pasteurized milk from 6 to 16 days when stored under cold conditions and from 8 to 18 h under room temperature conditions.     

Growth and Survival of Salmonella typhimurium at Low Temperature in Nutrient Deficient Media

The growth and survival of two strains of Salmonella typhimutium in nutrient-deficient media at 7°C were studied. Cultures were propagated at 37°C, 24°C or 7°C in tryptic soy broth (TSB), inoculated into optimal, minimal and nutrient-deficient media (TSB, 1% TSB; 1.0%, 0.1% and 0.01% peptone water; 0.1% and 0.01% nonfat dry milk; and 30% glycol with and without 0.1% added milk solids) and incubated at 7°C. Numbers at 7°C declined initially when first propagated at 37°C. No decline was seen when propagated at the lower temperatures (24°C and 7°C). S. typhimurium survived in all media for extended periods; one strain survived for more than 1 year at 7°C in 0.1% peptone water and TSB.     

添加豆浆对牦牛酸奶品质的影响

将不同添加量（0、20%、40%、60%）豆浆添加到牦牛乳中制备豆浆-牦牛酸奶,探讨不同添加量豆浆对牦牛酸奶理化指标、贮藏期内酸度、质构特性（硬度、稠度、黏聚性与黏性指数）、持水力、乳酸菌数和感官特性的影响。结果表明,在贮藏期内（1～14 d）,随着豆浆添加量在0～60%范围内增加,牦牛酸奶酸度、持水力、质构特性、乳酸菌数均有所下降。添加20%豆浆制备的牦牛酸奶蛋白质、脂肪及非脂乳固体含量分别为3.28 g/100 g、4.58 g/100 g、8.76 g/100 g,乳酸菌数＞107 CFU/mL,感官评分为87.9分,其酸度、持水力、质构、乳酸菌数等与未添加豆浆的对照相比均无显著差异（P＞0.05）。因此,在牦牛乳中添加20%的豆浆制备豆浆-牦牛酸奶是可行的,可进一步推广应用。