Determination of fat,protein, moisture,and salt content of Cheddar cheese using mid-infrared transmittance spectroscopy

The objective of our work was to develop and evaluate the performance of a rapid method for measuring fat, protein, moisture, and salt content of Cheddar cheese using a combination mid-infrared (MIR) transmittance analysis and an in-line conductivity sensor in an MIR milk analyzer. Cheddar cheese was blended with a dissolving solution containing pentasodium triphosphate and disodium metasilicate to achieve a uniform, particle-free dispersion of cheese, which had a fat and protein content similar to milk and could be analyzed using a MIR transmittance milk analyzer. Annatto-colored Cheddar cheese samples (34) from one cheese factory were analyzed using reference chemistry methods for fat (Mojonnier ether extraction), crude protein (Kjeldahl), moisture (oven-drying total solids), and salt (Volhard silver nitrate titration). The same 34 cheese samples were also dissolved using the cheese dissolver solution, and then run through the MIR and used for calibration. The reference testing for fat and crude protein was done on the cheese after dispersion in the dissolver solution. Validation was done using a total of 36 annatto-colored Cheddar cheese samples from 4 cheese factories. The 36 validation cheese samples were also analyzed using near-infrared spectroscopy for fat, moisture, and the coulometric method for salt in each factory where they were produced. The validation cheeses were also tested using the same chemical reference methods that were used for analysis of the calibration samples. Standard error of prediction (SEP) values for moisture and fat on the near-infrared spectroscopy were 0.30 and 0.45, respectively, whereas the MIR produced SEP values of 0.28 and 0.23 for moisture (mean 36.82%) and fat (mean 34.0%), respectively. The MIR also out-performed the coulometric method for salt determination with SEP values of 0.036 and 0.139 at a mean level of salt of 1.8%, respectively. The MIR had an SEP value of 0.19 for estimation at a mean level of 24.0% crude protein, which suggests that MIR could be an easy and effective way for cheese producers to measure protein to determine protein recovery in cheese making.     

酱油中食盐含量测定方法的比较和改进

酱油中食盐含量的测定方法已有报道,主要有莫尔法、佛尔哈德法、电位滴定法、氯离子选择电极法等,根据已有的方法将莫尔法进行改进、且自行设计灰化法进行实验,并与上述方法测定的结果比较,发现酱油中食盐含量在22.2g/100mL和22.3g/100mL之间。比较几种方法的准确度和精密度发现,它们各有不同的特点,电位滴定法和氯离子选择电极法有较好的准确度和灵敏度且操作简便,但对温度等外界条件和操作要求严格;其余的方法均需脱色处理,操作较繁琐;改进后的莫尔法能很好的解决脱色问题,但误差较大测得值偏低;自行设计的灰化法操作简单可行并有较好的准确度。     

Effect of zinc fortification on Cheddar cheese quality

Zinc-fortified Cheddar cheese containing 228 mg of zinc/kg of cheese was manufactured from milk that had 16 mg/kg food-grade zinc sulfate added. Cheeses were aged for 2 mo. Culture activity during cheese making and ripening, and compositional, chemical, texture, and sensory characteristics were compared with control cheese with no zinc sulfate added to the cheese milk. Compositional analysis included fat, protein, ash, moisture, zinc, and calcium determinations. The thiobarbituric acid (TBA) assay was conducted to determine lipid oxidation during aging. Texture was analyzed by a texture analyzer. An untrained consumer panel of 60 subjects evaluated the cheeses for hardness, off-flavors, appearance, and overall preference using a 9-point hedonic scale. Almost 100% of the zinc added to cheese milk was recovered in the zinc-fortified cheese. Zinc-fortified Cheddar cheese had 5 times more zinc compared with control cheese. Zinc-fortified cheese had higher protein and slightly higher fat and ash contents, whereas moisture was similar for both cheeses. Zinc fortification did not affect culture activity during cheese making or during the 2-mo aging period. The TBA value of control cheese was higher than that of zinc-fortified cheese at the end of ripening. Although zinc-fortified cheese was harder as determined by the texture analyzer, the untrained consumer panel did not detect differences in the sensory attributes and overall quality of the cheeses. Fortification of 16 mg/kg zinc sulfate in cheese milk is a suitable approach to fortifying Cheddar cheese without changing the quality of Cheddar cheese.     

Dynamic Headspace Analyses of Volatile Compounds of Cheddar and Swiss Cheese during Ripening

The volatile compounds of Cheddar and Swiss cheeses during ripening for 9 wks at 11°and 21°C, respectively, were analyzed by a dynamic headspace analyzer/gas chromatograph every week. The compounds were identified by a combination of retention times and mass spectra. The volatile compounds of Cheddar increased 5.6 and Swiss cheese 15 times as ripening increased from 0 to 9 wks. The amount of volatile compounds of Swiss cheese was 2.6 times greater than that of Cheddar cheese during ripening. The volatile compounds were ketones, alcohols, aldehydes, esters, acids, sulfur compounds, benzenes, and hydrocarbons. Ketones and alcohols accounted for 92% of volatiles from Cheddar cheese and 88% of those from Swiss cheese.     

Application of salt whey in process cheese food made from Cheddar cheese containing exopolysaccharides

The objective of this work was to use salt whey in making process cheese food (PCF) from young (3-wk-old) Cheddar cheese. To maximize the level of salt whey in process cheese, low salt (0.6%) Cheddar cheese was used. Because salt reduction causes undesirable physiochemical changes during extended cheese ripening, young Cheddar cheese was used in making process cheese. An exopolysaccharide (EPS)-producing strain (JFR) and a non-EPS-producing culture (DVS) were applied in making Cheddar cheese. To obtain similar composition and pH in the EPS-positive and EPS-negative Cheddar cheeses, the cheese making protocol was modified in the latter cheese to increase its moisture content. No differences were seen in the proteolysis between EPS-positive and EPS-negative Cheddar cheeses. Cheddar cheese made with the EPS-producing strain was softer, and less gummy and chewy than that made with the EPS-negative culture. Three-week-old Cheddar cheese was shredded and stored frozen until used for PCF manufacture. Composition of Cheddar cheese was determined and used to formulate the corresponding PCF (EPS-positive PCF and EPS-negative PCF). The utilization of low salt Cheddar cheese allowed up to 13% of salt whey containing 9.1% salt to be used in process cheese making. The preblend was mixed in the rapid visco analyzer at 1,000 rpm and heated at 95°C for 3 min; then, the process cheese was transferred into copper cylinders, sealed, and kept at 4°C. Process cheese foods contained 43.28% moisture, 23.7% fat, 18.9% protein, and 2% salt. No difference in composition was seen between the EPS-positive and EPS-negative PCF. The texture profile analysis showed that EPS-positive PCF was softer, and less gummy and chewy than EPS-negative PCF. The end apparent viscosity and meltability were higher in EPS-positive PCF than in EPS-negative PCF, whereas emulsification time was shorter in the former cheese. Sensory evaluation indicated that salt whey at the level used in this study did not affect cheese flavor. In conclusion, process cheese, containing almost 13% salt whey, with improved textural and melting properties could be made from young EPS-positive Cheddar cheese.     

The impact of reduced sodium chloride content on Cheddar cheese quality

The effect of varying salt (sodium chloride) addition levels of 0.50%, 1.25%, 1.80%, 2.25%, 2.50% and 3.00% (w/w) on the quality of Cheddar cheese was assessed. Reducing the salt adversely impacted Cheddar flavour and texture. The key compositional parameters of moisture-in-non-fat-substances and salt-in-moisture were most affected. Decreasing salt resulted in a concomitant reduction of pH, a slight reduction in buffering capacity and an increase in water activity and growth of starter and non-starter lactic acid bacteria that resulted in enhanced proteolysis. Lipolysis was not impacted by salt reduction. To produce quality reduced salt Cheddar cheese cognisance must be taken on how to reduce proteolysis, limit growth of NSLAB, reduce water activity, achieve pH 5.0–5.4 by modifications to the cheese making procedure to create a more appropriate environment for selected starter and/or adjunct cultures to generate acceptable Cheddar flavour and texture.     

Moderately High Hydrostatic Pressure Processing to Reduce Production Costs of Shredded Cheese: Microstructure, Texture, and Sensory Properties of Shredded Milled Curd Cheddar

ABSTRACT: Short and moderate hydrostatic pressure (MHP) treatments accelerated the shredability of Cheddar cheese. Both MHP (345 MPa for 3 and 7 min) and higher pressure (483 MPa for 3 and 7 min) treatments applied to 1-d milled curd Cheddar cheese induced immediately a microstructure resembling that of ripened cheese. Unripened pressure-treated Cheddar cheese yielded shreds with visual and tactile sensory properties similar to those obtained from untreated 27-d-old Cheddar cheese. All pressure treatments reduced the presence of crumbles, increased mean shred particle length, improved length uniformity, and enhanced surface smoothness. Sensory evaluations showed that shredded samples of 1-d MHP-treated cheese and 27-d untreated cheese had similar sensory attributes. Pressure treatments did not affect mechanical properties of ripened cheese and milk protein proteolysis was not inhibited. These results showed that MHP would allow processors to shred milled curd Cheddar cheese immediately after block cooling with expected refrigerated storage savings of more than $30 US/1000 kg cheese and could simplify the handling of cheese for shredding. Shreds from unripened milled curd Cheddar cheese can thus be produced with high visual acceptability and improved tactile handling using moderate levels of hydrostatic pressure.     

Alternative Test for Phosphorous in Cheese

A modified test for phosphorous in cheese based on quantitative precipitation, filtration, and indirect titration of milligram quantities of phosphorous is presented. The procedure was designed specifically for Cheddar cheese and was used to analyze a wide range of Cheddar samples including some with atypically high and low calcium and phosphorous. A modification of the procedure permitted measurement of total ash, calcium, and phosphorous in the same cheese sample. With reagent adjustments it is possible to test other cheese varieties as well as other dairy products.Average recovery of phosphorous from 10 replicate solutions containing known amounts of calcium and phosphorous was 99.1 ± .7%. Average recovery of phosphorous added to 10 replicate Cheddar cheese samples was 98.9 ± 1.5%. Ten Cheddar cheeses were analyzed in duplicate by the proposed method and by atomic emission. Results of the two methods differed by an average of .015% phosphorous, a significant difference, but the methods were strongly correlated (r =.94).Duplicate analyses by the proposed method were conducted on 54 Cheddar cheese samples ranging from .427 to .555% phosphorous. The average difference between duplicate measurements was .011 ± .009% phosphorous. The principle of the proposed test and modifications required for cheese analysis are discussed.     

The key aroma compounds and sensory characteristics of commercial Cheddar cheeses

To study the key aroma components and flavor profile differences of Cheddar cheese with different maturity and from different countries, the flavor components of 25 imported commercial Cheddar cheese samples in the China market were determined by gas chromatography-mass spectrometry. The quality and quantity of 40 flavor compounds were analyzed by gas chromatography-olfactometry among 71 aroma compounds determined by gas chromatography-mass spectrometry. Combined with odor activity value calculation, principal component analysis (PCA) was conducted to analyze the relationship among 26 flavor compounds with odor activity values >1 and the maturity of Cheddar cheese. The PCA results showed significant differences between the group of mild Cheddar cheese and the groups of medium Cheddar cheese and mature Cheddar cheese, and no significant differences were observed between medium Cheddar cheese and mature Cheddar cheese. According to the results of PCA and consumers' preference test, representative Cheddar cheese samples with different ripening times were selected for the flavor profile analysis. Partial least squares regression analysis was conducted to obtain the relationship between sensory properties and flavor compounds of different Cheddar cheeses. Based on partial least squares regression analysis, 1-octen-3-one, hexanal, acetic acid, 3-methylindole, and acetoin were positively correlated with milky, sour, and yogurt of mild Cheddar cheese. Dimethyl trisulfide, phenylacetaldehyde, ethyl caproate, octanoic acid, and furaneol and other compounds were positively correlated with fruity, caramel, rancid, and nutty notes of the medium and mature Cheddar cheeses.     

Elimination of the development of bitter flavour in Cheddar cheese made from milk containing heat-denatured whey protein

A method has been developed for increasing the yield of Cheddar cheese by as much as 7.5% by the incorporation of denatured whey protein in curd. The process effectively eliminates the development of intense bitter off-flavours which are generally associated with the production of cheese from acidified milk. Although the manufacturing procedure produces cheese with acceptable Cheddar flavour, the development of high quality Cheddar flavour is impaired     

Comparison of differences between lexicons for descriptive analysis of Cheddar cheese flavour in Ireland,New Zealand,and the United States of America

Flavour lexicons for cheese provide a way to document cheese flavour for both research and marketing. The objective of this study was to compare differences and similarities in three independently developed sensory languages for Cheddar cheese flavour at three different locations (Ireland, New Zealand, United States of America) using an international selection of Cheddar cheeses. Twelve Cheddar cheeses (four from each country) were evaluated by the three panels using the respective sensory languages. Sensory space patterns obtained by principal component analysis were consistent between the three sites indicating that the overall differentiation of the cheeses by each panel was similar. The key flavour characteristics among the cheeses were described by different attributes. Cheeses were grouped by each site by country of origin suggesting international differences in Cheddar cheese flavour. Cross-cultural differences can exist in sensory language and perception, but highly trained panels using standardized, representative languages can provide comparable results.     

Determining salt concentrations for equivalent water activity in reduced-sodium cheese by use of a model system

The range of sodium chloride (salt)-to-moisture ratio is critical in producing high-quality cheese products. The salt-to-moisture ratio has numerous effects on cheese quality, including controlling water activity (a_w). Therefore, when attempting to decrease the sodium content of natural cheese it is important to calculate the amount of replacement salts necessary to create the same a_w as the full-sodium target (when using the same cheese making procedure). Most attempts to decrease sodium using replacement salts have used concentrations too low to create the equivalent a_w due to the differences in the molecular weight of the replacers compared with salt. This could be because of the desire to minimize off-flavors inherent in the replacement salts, but it complicates the ability to conclude that the replacement salts are the cause of off-flavors such as bitter. The objective of this study was to develop a model system that could be used to measure a_w directly, without manufacturing cheese, to allow cheese makers to determine the salt and salt replacer concentrations needed to achieve the equivalent a_w for their existing full-sodium control formulas. All-purpose flour, salt, and salt replacers (potassium chloride, modified potassium chloride, magnesium chloride, and calcium chloride) were blended with butter and water at concentrations that approximated the solids, fat, and moisture contents of typical Cheddar cheese. Salt and salt replacers were applied to the model systems at concentrations predicted by Raoult's law. The a_w of the model samples was measured on a water activity meter, and concentrations were adjusted using Raoult's law if they differed from those of the full-sodium model. Based on the results determined using the model system, stirred-curd pilot-scale batches of reduced- and full-sodium Cheddar cheese were manufactured in duplicate. Water activity, pH, and gross composition were measured and evaluated statistically by linear mixed model. The model system method accurately determined the concentrations of salt and salt replacer necessary to achieve the same a_w as the full-sodium control in pilot-scale cheese using different replacement salts.     

The effect of age on Cheddar cheese melting,rheology and structure,and on the stability of feed for cheese powder manufacture

Age-related changes to the rheology and structure of Cheddar for cheese powder manufacture, and how this influences the stability of cheese feed during pre-spray-drying storage, were investigated. Cheddar cheese (3, 5, 7, 9, 12 and 15 months old) was analysed for meltability by the Schreiber Test and small angle oscillation measurements. Results showed increasing stiffness and reduced activation energy for initiation of milk fat melting with age. Cheese feeds for manufacture of cheese powder were made, with or without emulsifying salts (ES), and analysed for emulsion stability. In the absence of ES, feeds made from 3 month old Cheddar were significantly more stable than those made from 5 month old cheese. A similar significant increase in emulsion stability was observed for cheeses of 7 months of age compared with 12 months, indicating the necessity to use Cheddar cheese aged 3 months or less to produce stable cheese feeds without ES.     

Ultrafiltered milk reduces bitterness in reduced-fat Cheddar cheese made with an exopolysaccharide-producing culture

The objectives were to reduce bitterness in reduced-fat Cheddar cheese made with an exopolysaccharide (EPS)-producing culture and study relationships among ultra-filtration (UF), residual chymosin activity (RCA), and cheese bitterness. In previous studies, EPS-producing cultures improved the textural, melting, and viscoelastic properties of reduced-fat Cheddar cheese. However, the EPS-positive cheese developed bitterness after 2 to 3 mo of ripening due to increased RCA. We hypothesized that the reduced amount of chymosin needed to coagulate UF milk might result in reduced RCA and bitterness in cheese. Reduced-fat Cheddar cheeses were manufactured with EPS-producing and nonproducing cultures using skim milk or UF milk (1.2×) adjusted to a casein:fat ratio of 1.35. The EPS-producing culture increased moisture and RCA in reduced-fat Cheddar cheese. Lower RCA was found in cheese made from UF milk compared with that in cheese made from control milk. Ultrafiltration at a low concentration rate (1.2×) produced EPS-positive, reduced-fat cheese with similar RCA to that in the EPS-negative cheese. Slower proteolysis was observed in UF cheeses compared with non-UF cheeses. Panelists reported that UF EPS-positive cheese was less bitter than EPS-positive cheese made from control milk. This study showed that UF at a low concentration factor (1.2×) could successfully reduce bitterness in cheese containing a high moisture level. Because this technology reduced the RCA level (per g of protein) to a level similar to that in the control cheeses, the contribution of chymosin to cheese proteolysis would be similar in both cheeses.     

Key aroma compounds identified in Cheddar cheese with different ripening times by aroma extract dilution analysis,odor activity value,aroma recombination,and omission

To determine the odor-active compounds in Cheddar cheeses with different ripening times (6, 10, and 14 mo), 39 potent odorants of Cheddar cheeses were identified with a flavor dilution factor range between 1 and 512 by aroma extract dilution analysis. To further determine their contribution to the overall aroma profile of Cheddar cheeses, odor activity values of 38 odorants with flavor dilution factors ≥1 were calculated. A Cheddar cheese matrix was developed to determine the concentrations and the odor thresholds of these key aroma compounds. The result of the aroma recombinant experiment prepared by mixing the key aroma compounds in the concentrations in which they occurred in Cheddar cheeses showed that the overall aroma profile of the recombinant sample was very similar to that of Cheddar cheese. The main different compounds in Cheddar cheese with different ripening time were acetic acid, butanoic acid, dimethyl trisulfide, methional, hexanal, (E)-2-nonenal, acetoin, 1-octen-3-one, δ-dodecalactone, furaneol, hexanoic acid, heptanal, and ethyl caproate. This study could provide important information for researching and developing Cheddar cheese–related products.     

Characterisation of commercial Cheddar cheese flavour. 1: traditional and electronic nose approach to quality assessment and market classification

Commercial Cheddar cheese was manufactured using summer milk with two types of starter culture during a day in May and during a day in September 1999. Traditional approaches to quality assessment and market classification of Cheddar cheese were studied and potential application of electronic nose metal oxide semiconductor (MOS) gas sensor technology in these areas was investigated. A cheese-grader-classified cheese from each manufacturing period into two similar classes based on market specification of sensory character. The relationship between grader classification and cheese composition was investigated using principal component analysis and partial least squares-discriminant analysis. Grader classification of cheese manufactured in May was correlated with fat in dry matter, moisture and pH. Despite similar classification of cheeses manufactured in September, a corresponding relationship between grader assessment and composition was not obtained. The electronic nose classified cheese manufactured in May in a manner similar to the cheese-grader over a 6-month maturation period. The ability of the electronic nose to reproducibly discriminate classes of cheese manufactured in September, demonstrated potential application of MOS gas sensor technology in Cheddar cheese production.     

Improved Complexometric Determination of Calcium in Cheese

Accuracy and repeatability of complexometric methods for measuring calcium in cheese are limited by titration endpoints that are difficult to recognize. Much of this difficulty results from turbidity during titration. An alternative procedure is described in which 2 to 3 g of cheese are ashed, dissolved in dilute acid, and added calcium chloride is back titrated with ethylenediaminetetraacetic acid using hydroxy naphthol blue as indicator. Samples remain free of turbidity, and the titration endpoint is recognized easily.Recovery of calcium from solutions containing magnesium and phosphate was 100.9 ± .3%, indicating that a portion of sample magnesium (about 12%) also was measured. Error caused by magnesium recovery represented less than 1% of true calcium content.Analyses of 10 Cheddar cheese samples by the proposed method and by atomic emission differed by an average of .010% calcium. Mean values of the 10 samples did not differ significantly (P>.05) between methods. Duplicate analyses of 67 Cheddar cheese samples differed by an average of .008 ± .006% calcium. Similar repeatability was achieved by several inexperienced analysts. The method is applied readily to other dairy products.     

Effect of Total and Partial Substitution of Sodium Chloride on the Quality of Cheddar Cheese

Cheddar cheese was manufactured to give 1.6% residual sodium chloride or equivalent amounts (ionic strength basis) of magnesium chloride, calcium chloride, potassium chloride, or 1:1 mixtures of sodium chloride and the chloride salt of magnesium, calcium, or potassium from two split batches of curd. Sensory evaluation after 4 mo ripening at 4°C showed that cheese salted solely with magnesium chloride, calcium chloride, or potassium chloride was extremely bitter and totally unacceptable. There was extensive lipolysis (as measured by free fatty acid development) in the cheese salted with magnesium chloride, calcium chloride, or potassium chloride. Proteolysis was highest in the cheese salted with calcium chloride and magnesium chloride. These cheese gave the lowest Instron values for firmness, hardness, and cuttability. Extensive proteolysis in these cheese may be partly due to the low salt in moisture. Taste panel scores for flavor and texture of the sodium chloride/calcium chloride and sodium chloride/magnesium chloride salted cheese were significantly lower than the scores for the control cheese. Scores for flavor and texture of the potassium chloride/sodium chloride salted cheese were not significantly different from scores of the control cheese.