Elaboration of an yogurt made of a milk and chickpea (Cicer arietinum) mixture

The objective of this work was to establish the experimental conditions for the production of yogurt extended with chickpea (Cicer arietinum), inoculated with St. thermophilus and L. bulgaricus and compare its chemical, microbiological and sensorial characteristics versus a yogurt made of skimmed milk. Results indicated that 70:30 and 80:20 (skimmed milk and chickpea extract) mixtures obtained by chemical score fulfilled with the proposed objectives. Yogurt made with 70:30 mixture added with modified starch (ULTRA SPERCE M and COL-FLO), did not remove syneresis present in these products and did not improve its sensory characteristics neither. Nevertheless, yogurt made with 80:20 mixture and modified starch (ULTRA SPERCE M) removed syneresis and present flavor and texture characteristics alike yogurt made of milk, this "extended" yogurt was accepted by the 80% of the judge and fulfill with yogurt specification established in the mexican regulations for this products.     

Studies on the development of infant foods from plant protein sources. Part III. Preparation, processing and properties of various products developed

Studies have been carried out on the development of a low-cost, high-quality infant food of low paste viscosity from rice, chickpea (Cicer arietinum) and cow's milk. In order to improve the overall quality of the product, chickpea was processed by different methods prior to its incorporation. A number of formulations was prepared by mixing 52% rice, 30% each, the processed chickpea sample, and 18% whole milk powder. These mixtures were processed by extrusion cooking or drum drying. In the case of the extrusion cooking method, from the nutritional and technological points of view, it was found advantageous to incorporate milk powder after cooking a mixture of rice and chickpea. The values of net protein ratio (NPR) of the products developed, whether processed by extrusion cooking or drum-drying methods, were statistically equal, and not significantly different from those of casein. Supplementing the product with methionine and threonine showed no effect in improving the NPR value, suggesting that these amino acids were not limiting. There were slight differences in the digestibilities of proteins in the products developed and all were lower than that of casein. Depending on the processing method, differences were observed in paste viscosities of the products. After partial hydrolysis of the products with pounds amylase, both the cold and hot paste viscosities were greatly reduced and were comparable with those of whole milk powder. From the results herein reported, it can be concluded that the drum-dried product prepared using rice:chickpea (carbonate presoaked):milk (52:30:18) is the best of all the products developed. Its amino acid composition compares favorably with that of the milk proteins.     

Sanitary and technologic evaluation of the rural processing of fresh goat cheese in Chile

A sanitary and technological diagnosis of the goat cheese rural process was carried out. The purpose was to obtain more information for the planning of a program aimed to the improvement of this small agroindustry. Samples of milk, curdle, dry abomasum, rennet, water and cheese of 10% of the small industries of two rural villages in two agricultural seasons, were taken. Moreover, dilutions of the utensils and goat udders were prepared. The samples were subjected to microbiological analysis of mesophilic aerobic bacteria count, most probable number of total and fecal coliforms, and detection of Staphylococcus aureus coagulase (+), Salmonella typhi and Brucella melitensis. Proximate chemical analysis and determinations of sodium chloride and titratible acidity in milk, cheese, dry abomasum and rennet, were carried out. Goat milk was also subjected to analysis of density. It was found that significant sanitary failures are present during th whole goat cheese process, although the highest bacteria contamination occurred at the milking, curdling and filling stages. These are characterized by excessive handling and absolute lack of hygiene. The pathogen B. melitensis was absent; therefore the causes of poisoning were attributed to the toxin produced by S. aureus and to the significant count of fecal coliforms found in the goat cheese. Even though the goats are fed under a poor feeding system, the milk presented a normal physical and chemical composition. Nevertheless, protein and fat matter losses occur during cheese preparation, as a result of handling practices and lack of process control.     

The use of appropriate technologies to improve the sanitary quality and the yield of goat cheeses in little farms

The purpose of this study was to increase the microbiological quality and yields of goat cheese prepared at farm level. For this purpose, appropriate technologies for the cheese-making process were designed, using a curd tank heated by gas, and cheese knives adjusted to the tank dimensions. Moreover, a low-cost table for whey draining and PVC moulds, were designed. Variables assayed were milk pasteurization, utilization of lactic acid starter by direct application, substitution of the kid rennet by commercial calf rennet, and cheese maturation for a one-month period. The control sample was goat cheese traditionally made by the small farmers. Processing and variables were evaluated by proximate chemical analysis, microbiological counts of aerobic mesophilic bacteria, total and fecal coliforms, and S. aureus; as well as by sensory evaluation of quality and acceptability. It was found that the cutting of curd with cheese knives significantly decreased solid losses in the whey. The addition of the starter and then the cheese maturation, as well as the use of the equipment previously described, increased the microbiological quality of cheese to standard sanitary regulation. Although pasteurization was the most effective treatment in decreasing bacteria contamination, this thermal treatment was difficult to be done under arid zones conditions. Commercial calf rennet did not differ significantly from kid rennet in the characteristics analyzed in this assay. Variables studied did not affect the normal sensory quality of goat cheese.     

A kiwi juice aqueous solution as coagulant of bovine milk and its potential in Mozzarella cheese manufacture

In this work a kiwi juice aqueous solution was prepared and used as coagulant enzyme in the manufacturing process of mozzarella cheese. The aqueous solution does exhibit high levels of milk-clotting activity probably due to the presence of the clotting enzyme actinidin in mixture with other kiwi fruit proteolityc enzymes. The mozzarella cheese was manufactured from bovine milk with a yield of 10.6% being in the range of that routinely obtained during cheese manufacture. A preliminary evaluation of the cheeses flavor showed positive results and lack of bitterness. Finally, in view of a future marketing of the kiwi juice aqueous solution as plant coagulant, it is shown that the aqueous solution stored for 20 days at −20 °C maintains both the clotting and proteolytic activities unaffected. Due to its properties as well as to the accessibility of the primary source for the preparation of the aqueous solution, it might represent a good candidate for calf rennet substitution, provided that further research on cheese properties will be carried out.     

Obtaining a fermented chickpea extract (Cicer arietinum L.) and its use as a milk extensor

Chickpea (Cicer arietinum L) is cultivated in the North part of México and it is considered a good source of vegetal protein of low cost (20% average), nevertheless, the 80% used for the exportation and only the 20% less was used for animal feeding. The main objective in this study is to obtain a fermented chickpea extract for using in dairy extensor. Chickpea water absorbtion kinetics were carried out in e temperature conditions:while the conditions were established, chickpea was grounded and fermented in different amounts with its natural flora, L. casei, L. plantarum and a mixture culture of both microorganism in logarithmic phase. The results showed that the presence of microorganism of chickpea natural flora interferes during the fermentation, so before the inoculation it was necessary treat the chickpea extract (CE) terminally in a dilution 1:4 during 20 min at 7.7 kg/cm2 of pressure. The use of a mixture culture of 5% of L. casei and 5% L. plantarum inoculated in MRS broth was used to decrease fermentation time. Its addition in logarithmic phase to the sterile chickpea extract increased the lactic acid production and decreased the pH value in 6 h which was less time that one obtained with each of lactobacillus. The fermented extract obtained finally, presented similar sensory characteristics to the ones of dairy products. Therefore, chickpea is a good alternative as a extensor for this kind of products.     

Application of cross-flow microfiltration to semi-hard cheese production from milk retentates

In the cheese industry, the concentration of milk using ultrafiltration for continuous soft and fresh cheese production is standard technology. The object of the work presented here was to produce a semi-hard cheese of quality and composition comparable to that of traditionally made cheese from highly concentrated microfiltered milk retentate. Two different membrane systems were tested for the production of high viscous milk retentate with high dry matter content. For milk containing 3.2% fat and skim milk, a concentration factor of 6.6 and 9.1 respectively was obtained using the MF/UF/UF pilot plant fitted with cassette modules. Milk containing 3.2% fat was concentrated in batches by a factor of 5.7 in the pilot plant using a ceramic membrane. Using minimal curd separation, a semi-hard one day old cheese with a dry matter of 533 g/kg, moisture on a fat-free basis (MFFB) of 626 g/kg and fat on a dry basis (FDB) value of 478 g/kg was made from the milk retentate produced with the ceramic module. The ripened cheese fulfilled the legal requirements of a traditionally produced semi-hard cheese with superb sensory qualities. Using the MF/UF/UF plant, a dry matter of 495 g/kg (MFFB 669 g/kg, FDB 493 g/kg) was achieved in a semi-hard cheese made from skim milk retentate. Our results suggest that by using a larger spacer distance in the last loop of the MF/UF/UF plant, combined with new hybrid technologies, semi-hard cheese production from full concentrate milk will soon become possible.     

Differential scanning calorimetry of water buffalo and cow milk fat in mozzarella cheese

The thermal profiles of the fat in mozzarella cheeses made from cow milk (CM) and water buffalo milk (WBM) were obtained by differential scanning calorimetry (DSC). The DSC curves of mozzarella cheese made from WBM were distinguishable from those of CM. The curves resembled those of the corresponding milk fats and could be divided into low-, medium-, and high-temperature melting regions. The valley in the curve between the low- and medium-temperature melting regions was at 10.8°C in WBM cheese and below 10°C in CM cheese. In the WBM cheese, the area of the low-melting region was larger than the area of the medium-temperature melting region, but the two areas were equal in the CM cheeses. Mixtures of the two cheeses exhibited temperature and area values between those of the pure cheeses. Milk-fat mixtures showed similar behavior. The contrasting DSC melting profiles provide a way of distinguishing between the two mozzarella cheese types and for detecting mixtures of the two fats in mozzarella cheese.     

Conjugated linoleic acid concentration in processed cheese

The conjugated linoleic acid (CLA) concentration of a variety of processed cheese products ranged between 3.2 to 8.9 mg/g fat. Processing cheddar cheese at temperatures of 80°C and 90°C under atmospheric conditions increased (p < 0.05) CLA content, while processing under nitrogen (70°C, 85°C) had no effect. Increasing concentrations of whey protein concentrate (WPC) and its low molecular weight (LMW) fraction from 0 to 6% increased CLA formation. Six percent WPC and LMW fraction produced a 35% and 19% increase in CLA concentration, respectively, compared to processed cheese. The high molecular weight fraction of WPC did not increase CLA concentration. These results suggest that processing conditions and whey components play a role in CLA formation in processed cheese.     

An Investigation and Quantitative Assessment of Particle Shape in Milk Powders from a Laboratory-Scale Spray Dryer

Seven samples of spray-dried milk were prepared using a miniature-scale Buchi Mini Spray Dryer B-290 (diameter 0.5 m, height 1.1 m). For each run, all inlet conditions were held constant except for feed type, inlet solids concentration, and inlet temperature. Skim milk at a solids concentration of 8.8% and whole milk at a solids concentration of 11% were dried at two inlet temperatures, 120 and 200°C. Lactose-free skim milk (8.8% solids concentration) and skim milk at a solids concentration of 41.2% were also dried at an inlet temperature of 200°C to assess the effects of milk feed type and inlet concentration, respectively. Equilibrium between the outlet product moisture content and the outlet gas conditions in the miniature spray dryer was not reached, unlike previous results for pilot-scale and larger dryers, so it appears that, in small (miniature-scale) dryers, the outlet moisture content is limited by kinetics and not by equilibrium. Calculated yields ranged from 10.4 to 82.7%, with whole milk giving significantly lower yields than skim milk, due to the sticky nature of fat found in whole milk. Lactose-free skim milk produced lower yields than skim milk dried at the same conditions, indicating that the lower glass-transition temperatures of the converted lactose sugars make these powders stickier. This sugar effect was not as large as that of the fat content. Comparisons between the SEM images, fractal dimensions, particle size distributions, and bulk densities showed that lower inlet temperatures produced particles of a more collapsed nature with a higher bulk density and lower fractal dimension than milk particles dried at higher temperatures. Also, feed solids concentration heavily influenced the shape of the particles, with high concentrations producing more spherical, less broken or shriveled particles with higher fractal dimensions, as the shell walls are thicker under these conditions. The fractal dimensions appeared to give generally consistent results for quantifying the average particle shapes.     

An Investigation and Quantitative Assessment of Particle Shape in Milk Powders from a Laboratory-Scale Spray Dryer

Seven samples of spray-dried milk were prepared using a miniature-scale Buchi Mini Spray Dryer B-290 (diameter 0.5 m, height 1.1 m). For each run, all inlet conditions were held constant except for feed type, inlet solids concentration, and inlet temperature. Skim milk at a solids concentration of 8.8% and whole milk at a solids concentration of 11% were dried at two inlet temperatures, 120 and 200°C. Lactose-free skim milk (8.8% solids concentration) and skim milk at a solids concentration of 41.2% were also dried at an inlet temperature of 200°C to assess the effects of milk feed type and inlet concentration, respectively. Equilibrium between the outlet product moisture content and the outlet gas conditions in the miniature spray dryer was not reached, unlike previous results for pilot-scale and larger dryers, so it appears that, in small (miniature-scale) dryers, the outlet moisture content is limited by kinetics and not by equilibrium. Calculated yields ranged from 10.4 to 82.7%, with whole milk giving significantly lower yields than skim milk, due to the sticky nature of fat found in whole milk. Lactose-free skim milk produced lower yields than skim milk dried at the same conditions, indicating that the lower glass-transition temperatures of the converted lactose sugars make these powders stickier. This sugar effect was not as large as that of the fat content. Comparisons between the SEM images, fractal dimensions, particle size distributions, and bulk densities showed that lower inlet temperatures produced particles of a more collapsed nature with a higher bulk density and lower fractal dimension than milk particles dried at higher temperatures. Also, feed solids concentration heavily influenced the shape of the particles, with high concentrations producing more spherical, less broken or shriveled particles with higher fractal dimensions, as the shell walls are thicker under these conditions. The fractal dimensions appeared to give generally consistent results for quantifying the average particle shapes.     

The effect of D‐glucose on milk clotting activity of Mucor miehei in a chemostat with biomass retention

In this study microbial production of rennin from a commercial strain of Mucor miehei (NRRL 3420) has been accomplished in a continuously fed fermenter. The effects of feed D ‐glucose concentration (2.5–30 g dm⁻³) on milk clotting activity and on other system variables were investigated at optimum mixing and dilution rates of 400 rpm and 0.0052 h⁻¹, respectively, without pH control. Maximum milk clotting activity (1.24 IU cm⁻³) occurred when the feed D ‐glucose concentration was 7.5 g dm⁻³. Enzyme production continued for 500 h, producing a total milk clotting activity of 10 230 IU. At the maximum milk clotting activity point, total protein concentration, milk clotting and proteolytic activities were analysed and compared with those of a commercial rennet. The ratio of milk clotting activity to proteolytic activity, and specific milk clotting activity were determined as 1.55 × 10⁻³ IU PU⁻¹ and 5.28 IU mg⁻¹ medium protein, respectively, denoting similar characteristics to a commercial rennet after concentration of the fermentation medium. © 1999 Society of Chemical Industry     

Spray Drying of Skim Milk Mixed with Milk Permeate: Effect on Drying Behavior,Physicochemical Properties,and Storage Stability of Powder

The possibility of using milk permeate (MP) to lower the protein level of skim milk powder (SMP) in producing powders of 34% and lower protein is explored. Skim milk suspensions with various levels of MP were prepared by mixing SMP and MP powder (MPP) at the ratios of 1:0, 7:3, 3:7, and 0:1: from 34 to 5.3% protein. The suspensions were dried in a spray dryer with inlet and outlet temperatures of 180 and 80°C, respectively. Increasing permeate concentration in the mixture showed a greater tendency to stickiness manifested by lowered the cyclone recovery of the powder as more powder stuck on the wall of the dryer. Increasing permeate concentration in the resultant powder did not significantly affect the bulk density but led to a reduction in the particle size and also made the powder slight green and yellowish in color. It also found to lower the glass transition temperature (T_g ) of the skim milk powder (SMP) and induce crystallization of lactose at lower water activity (a_w  ≥ 0.328 for SMP:MPP of 3:7 and 0:1 compared to a_w  ≥ 0.0.432 for SMP:MPP of 1:0 and 3:7). Addition of MP in SMP lowered the T_g values of the resulting powders. The permeate fraction in spray-dried SMP/MPP mixtures found to lower the critical a_w and moisture content, suggesting the SMP mixed with MPP is more likely to become sticky than SMP alone (at 34% protein) when stored at a similar water activity and moisture content.     

Fatty acids and polar lipid content of cheese and mould‐contaminated cheese

Unintended infestation of food with viable mould irreversibly leads to spoilage of food. However, little data existed on the fatty acid composition and polar lipid content of mould grown on cheese and the potential influence of these parameters in mould‐infested cheese. In this study, we thus focused on the fatty acids composition and polar lipid content of cheese, mould isolated from mould‐infested cheese, as well as inoculation of cheese with cultures of isolated moulds. For this purpose, we stored three cheese samples (gouda, brown cheese, and parmesan) over extended periods in order to force mould infestation from air. The moulds grown on gouda and brown cheese were identified as Penicillium brevicompactum and Penicillium roqueforti, respectively, while a mixed culture was obtained from parmesan. From these contaminated samples, mould spores were isolated and cultivated. Finally, the (pure) cheeses were inoculated with mould spores. Three subsamples, (1) cheeses, (2) moulds isolated from cheese, and (3) cheeses infested with the isolated moulds were studied with regards to their fatty acid distribution in the neutral and the polar lipids. The different amounts of polar lipids of cheese (0.39–2%), moulds (11–30.7%), and mould‐infested cheese (1.5–5%) allowed calculating the mould content of the mould‐infested cheeses.     

Isolation of Gram-positive bacteria from raw milk with antimicrobial residues

Two hundred samples of raw milk were collected at the receiving plants located in three areas of high milk production in Zulia state, Venezuela. The CTT test and trial disk were used in order to detect the presence of antimicrobials. The positive samples were inoculated in tripticase soy broth, human blood agar and manitol salt agar in order to isolate Gram-positive bacteria. The identification of species was performed through biochemical tests. It was found that 45 samples (22.5%) of analyzed milk contained antimicrobials, and bacterial growth was obtained in 35 of them. 100 strains were isolated namely: 44 Staphylococcus, 19 Streptococcus, 17 Enterococcus, 9 Bacillus, 4 Micrococcus, 4 Corynebacterium and 3 Lactococcus. The most frequently isolated specie was S. aureus, the main producing agent of bovine mastitis in Zulia state, a microorganism frequently associated in the country to food-borne intoxications, associated to cheese processed from raw milk. It is recommended to apply control programs for the use of antibiotics.     

Inactivation of Baculovirus by Isoflavonoids on Chickpea (<Emphasis Type="Italic">Cicer arietinum</Emphasis>) Leaf Surfaces Reduces the Efficacy of Nucleopolyhedrovirus Against <Emphasis Type="Italic">Helicoverpa armigera</Emphasis>

Biological pesticides based on nucleopolyhedroviruses (NPVs) can provide an effective and environmentally benign alternative to synthetic chemicals. On some crops, however, the efficacy and persistence of NPVs is known to be reduced by plant specific factors. The present study investigated the efficacy of Helicoverpa armigera NPV (HearNPV) for control of H. armigera larvae, and showed that chickpea reduced the infectivity of virus occlusion bodies (OBs) exposed to the leaf surface of chickpea for at least 1 h. The degree of inactivation was greater on chickpea than that previously reported on cotton, and the mode of action is different from that of cotton. The effect was observed for larvae that consumed OBs on chickpea leaves, but it also occurred when OBs were removed after exposure to plants and inoculated onto artificial diet, indicating that inhibition was leaf surface-related and permanent. Despite their profuse exudation from trichomes on chickpea leaves and their low pH, organic acids—primarily oxalic and malic acid—caused no inhibition. When HearNPV was incubated with biochanin A and sissotrin, however, two minor constituents of chickpea leaf extracts, OB activity was reduced significantly. These two isoflavonoids increased in concentration by up to 3 times within 1 h of spraying the virus suspension onto the plants and also when spraying only the carrier, indicating induction was in response to spraying and not a specific response to the HearNPV. Although inactivation by the isoflavonoids did not account completely for the level of effect recorded on whole plants, this work constitutes evidence for a novel mechanism of NPV inactivation in legumes. Expanding the use of biological pesticides on legume crops will be dependent upon the development of suitable formulations for OBs to overcome plant secondary chemical effects.     

Prediction of seasonal variation of butters by computing the fatty acids composition with artificial neural networks

The seasonal variation of the fatty acids composition of butters were investigated over three seasons during a 12‐month study in the protected designation of origin Parmigiano‐Reggiano cheese area. Fatty acids were analyzed by GC‐FID, and then computed by artificial neural networks (ANN). Compared with spring and winter, butter manufactured from summer milk creams showed an optimal saturated/un‐saturated fatty acids ratio (?8.89 and ?5.79%), lower levels of saturated fatty acids (?2.63 and ?1.68%) and higher levels of mono‐unsaturated (+5.50 and +3.45%), poly‐unsaturated fatty acids (+0.65 and +0.17%), and rumenic acid (+0.55 and +3.41%), while vaccenic acid had lower levels in spring and higher in winter (?2.94 and +2.91%). Moreover, the ANN models were able to predict the season of production of milk creams, and classify butters obtained from spring and summer milk creams on the basis of the type of feeding regimens. Practical applications: The investigation on variables that affect the milk fatty acids composition can improve the quality of milk across all systems, and the combination of chromatographic and computational techniques will ensure a secure traceability enabling producers to characterize dairy products.     

用聚合型乳化剂制备反相乳液的研究

以丙烯酸钠水溶液为水相,煤油为油相,Span80甲基丙烯酸酯(Span80 MA)聚合型乳化剂、Span80和Twen80为复配乳化剂,制备反相乳液。计算聚合型乳化剂(Span80MA)的HLB值,考察了乳化剂浓度、水相体积分数φ及单体浓度对乳液类型及稳定性的影响规律。结果显示:HLB(Span80MA)=4.0;形成稳定的反相乳液理想条件为:Span80MA∶Span80∶Twen80=0.7∶0.5∶0.2;乳化剂浓度为7%;φ=50%;单体浓度为2.0～3.0 mol/L。     

The rapid determination of aflatoxin M1 in dairy products

A method for aflatoxin M₁ in dairy products is presented. It decreases the analysis time compared to currently accepted methods. Samples are extracted in a blender or separatory funnel for 1 min with chloroform and saturated sodium chloride solution. The chloroform extracts are partially purified on a small silica gel column (2 g), and M₁ is determined by thin layer chromatography (TLC) and densitometry. Recoveries of M₁ added to milk are about 80%. Recovery of M₁ from cheeses is variable depending on the type of cheese. The method gave results for a naturally contaminated powdered milk comparable to analyses by accepted methods. The determination limit of the method is about 0.1 μg/kg.     

A laboratory investigation of cow and camel whey proteins deposition under different heat treatments

Using a developed laboratory scale device, different heat treatment conditions were applied on camel and cow wheys. After each deposition experiment, photos of stainless steel plates were taken and dry deposit weights were determined. Proteins denaturation was studied by electrophoresis (SDS-PAGE) and differential scanning calorimetry (DSC). The obtained results have shown that heating both cow and camel wheys at 60 °C does not generate deposit. Furthermore, the heat treatment at above 70 °C was found to cause a severe fouling of stainless steel plate. The electrophoresis patterns indicated that heating at 90 °C caused camel serum albumin's (CSA) band disappearance for both rennet and acid wheys. However, α-lactalbumin's (α-la) concentration decreased versus temperature and heating time. DSC thermograms showed that denaturation temperatures were 73.8 °C for camel rennet whey, 60.5 °C for camel acid whey, 70.5 °C for cow rennet whey and 63.9 °C for cow acid whey. Taken into the count the absence of β-lg in camel milk and based on the obtained results several hypotheses were advanced to explain camel milk fouling during heat treatment.