Dairy Foods: Cheese
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Dairy Foods: Cheese T66 An x-ray system to assess Ragusano PDO quality. G. Impoco1, significant effect on functional properties of imitation cheeses between C. Pasta1, G. Portelli1, G. Marino1, M. Caccamo*1, S. Carpino1, and G. RVA at 450 rpm and Stephan cooker at 1,500 rpm. The microstructure Licitra1,2, 1CoRFiLaC, Regione Siciliana, Ragusa, Italy, 2D.A.C.P.A., of imitation cheeses observed by scanning electron microscopy, showed University of Catania, Catania, Italy. that increasing stirring speed seemed to reduce the fat globules size and form a uniform protein matrix. In the sensory evaluation, the imitation Accept/reject judgments in Ragusano Protected Designation of Origin cheese manufactured by RVA at 450 rpm was not a significant difference (PDO) quality assessment are highly subjective due to the lack of stan- with the control made by the Stephan cooker. The RVA can be used as dard evaluation protocols. Moreover, assessment takes place on aging a small-scale manufacturing tool for making the imitation cheeses with centers. X-ray scanning is a mature technology used in the industrial similar functional properties. chain to inspect the inner structure of food. The use of x-ray images of cheese blocks was investigated to judge cheese quality, the main reason Key Words: imitation mozzarella cheeses, rapid visco analyzer (RVA), being that this technique is non-destructive. Moreover, evaluating quality functional properties on a common ground would open the possibility of devising quantita- tive image analysis tools, inspired by objective evaluation protocols. An evaluation scale was created to objectively score cheese blocks by T68 A sensor technology for monitoring and controlling syneresis 1 ` 1 visual inspection of x-ray images. According to inspectors’ suggestions, in the cheese vat. T. G. Ferreira* , M. Castillo , F. A. Payne , C. 3 4 1 7 relevant criteria were chosen. Six inspectors assessed these parameters O’Donnell , and D. O’Callaghan , University of Kentucky, Lexing- 2 3 on a few test images of Ragusano PDO and assigned a weight to each ton, Universitat Autònoma de Barcelona, Spain, University College 4 of them. Then, a 7-item on a 9-point semantic differential scale was Dublin, Ireland, Moorepark Food Research Center, Teagasc, Fermoy, created. A data set of 223 images manually evaluated cheese blocks Co. Cork, Ireland. was collected. From this data set, 64 images were randomly extracted. Cheese quality is affected by curd moisture content which is determined Images were evaluated using the scale Furthermore, inspectors also during the whey syneresis step. The syneresis step in cheese process- assessed cheese acceptability only based on images by using a yes/no ing is currently controlled empirically by the processor as there are no criterion. Two weeks later, inspectors observed the same 64 images on-line sensor technologies available for monitoring curd syneresis. A only to evaluate cheese block acceptability, with no scale use. Results novel non-destructive optical sensor technology that is able to monitor of both experiments were compared with the on-field evaluation to both milk coagulation and curd syneresis in a stirred cheese vat has determine whether the scale was useful for quality assessment. The scale been developed. The objective of this study was to evaluate the per- presented a final reliability with both Cronbach’s α test and standardized formance of the sensor technology over a wide range of coagulation Cronbach’s α of about 0.81. Construct validity assessed on all 7 items and syneresis rates. A 5-factor, fully randomized, fractional, factorial resulted in a 2-factor solution that explained 79.5% of the scale vari- central composite design (CCD) was employed. The 5 experimental ance. By using the scale, cheese acceptability evaluated by images was factors selected were milk coagulation temperature, milk pH, fat to consistent with on-field evaluation for 62% of cheese blocks, whereas protein ratio, calcium chloride addition level, and gel cutting time. The without the scale consistency dropped down to 37%. CCD consisted of a 2k-1 factorial (k = 5) with 2k axial points and 7 Key Words: quality evaluation, cheese, x-ray imaging center points (33 runs). A homogeneous sample of curd and whey was removed from the cheese vat from 5 until 85 min after cutting on 10 min intervals. Fat, protein and total solids content of whey, curd, and T67 Effects of rapid visco analyzer on the functional properties of milk were determined. Also, the weight of curd and whey produced was imitation mozzarella cheese. S. He1,2, X. Li*1,2, Y. Ma3, C. Yao2, and expressed as a percentage of the initial weight of milk to provide the B.Wu1,2, 1Key Laboratory of Dairy Science, Northeast Agricultural Uni- actual curd and whey yield. A curd aliquot was pressed for determina- versity, Ministry of Education, Harbin, Heilongjiang, China, 2College of tion of pressed cheese moisture content. Results confirmed previously Food Science, Northeast Agricultural University, Harbin, Heilongjiang, observations for both curd moisture content and light backscatter ratio China, 3School of Food Science and Engineering, Harbin Institute of changes during curd syneresis. The largest change in curd moisture Technology, Harbin, Heilongjiang, China. content was observed during the first 15–30 min of syneresis. However, significant moisture content changes were observed in pressed cheese A small-scale manufacturing method of imitation cheese was developed samples at all different post-cutting times. These results clearly suggest by a rapid visco analyzer (RVA). In this work, imitation mozzarella an important role of syneresis end point selection on moisture content cheeses with similar chemical compositions, made by RVA at a stir- consistency of fresh, pressed cheeses. Successful validation and of the ring speed of 200, 300 or 450 rpm and by the Stephan cooker at 1,500 syneresis sensor technology scale up and subsequent transference to rpm, were investigated through functional properties, microstructure the industry will have a large impact on cheese production efficiency and sensory evaluation. A color measurement instrument (model and cheese yield. Not only will the sensor have industrial applications, ZE-6000, Nippon Denshoku Industries CO., Ltd., Japan) revealed it could also serve as a powerful tool for research. that the increase of stirring speed in RVA method made the color more white. Within the range of speeds in the present study, the relationship Key Words: on line sensor, syneresis, moisture content control between the minimum apparent viscosity (y, cP) and speeds (x, rpm) was best described by a linear model y = 0.9x + 685.3 (r2 = 0.968). Through free-oil release analysis, the fat leakage of imitation cheese T69 Method to quantify retention of lipid soluble substances in a at 450 rpm was significantly higher than the others. On the Texture cheese curd model system. M. Tippetts* and S. Martini, Utah State profile analysis (TPA), the hardness of imitation cheese significantly University, Logan. increased, and the adhesiveness sharply decreased while the springiness The purpose of this study was to find a way to quantify how much of an and cohesiveness values remained unchanged. However, there was not a emulsion′s lipid soluble substances are retained in a cheese curd model 328 J. Anim. Sci. Vol. 88, E-Suppl. 2/J. Dairy Sci. Vol. 93, E-Suppl. 1/Poult. Sci. Vol. 89, E-Suppl. 1 system by image analysis rather than alternate methods such as HPLC. T71 Effect of addition of calcium chloride and sodium chloride Soybean oil (SBO) was the oil phase and it was saturated with Nile on aflatoxin M1 content during Egyptian Domiatti cheese process- red, which is an indicator for liposoluble substances. The oil-in-water ing. M. M. Motawee*1, K. Genedy1, and T. A. Nassib2, 1National emulsion was made using a 1 wt % protein non-fat dairy powder aque- Organization for Drug Control and Research, Giza, Cairo, Egypt, 2Fac- ous solution, and a 5 wt% oil phase. The saturated Nile red SBO was ulty of Agriculture, Mansoura University, Mansoura, Egypt. added to the system as 0, 20, 40, 60, 80, and 100% of the total SBO. Aflatoxins are highly toxic, mutagenic and carcinogenic compounds Each emulsion was homogenized using a microfluidizer. After emulsion producing by some common molds as Aspergillus flavus and Aspergil- formation 5 mL of the emulsion were pipetted into pre-heated 3.36 wt% lus parasiticus during their growth on feedstuffs. Domiatti cheese is the protein milk protein concentrate solution. The ratio of emulsion to milk most popular soft white pickled cheese in Egypt and makes up about solution was 1:40. Curd was made and then samples were taken of each of the 75% of the cheese produced and consumed in our country. The sample, placed in a mold and under UV light images were taken using proportion of salt (5 to 14%) depends on the season of manufacture and an ethium bromide filter, which excited the Nile Red in the curd. The on the temperature of cheese ripening. The present study was aimed to images were then analyzed using ImageJ software′s macro for RGB analyze the level of aflatoxin M1 (AFM1) by thin layer chromatogra- histogram. The intensities of red (histogram) for the mean and mode phy method in pasteurized milk, curd and whey after spiked milk with were plotted with respect to the concentration of Nile red. Data was (AFM1) during Domiatti cheese processing. The results indicated that, fitted using linear regression with R2 values of 0.994 (mean) and 0.996 the addition of CaCl at the different concentration (0.01, 0.02, 0.03, (mode). The correlation found for each measurement is: y = 0.379x + 2 0.04 and 0.05%) had slight significant effect of AFM1 content in pas- 7.361 and y = 0.392x + 5.385 for the mean and mode, respectively.