Accelerated Cheddar Cheese Ripening with an Aminopeptidase Fraction from Squid Hepatopancreas

ABSTRACT: An aminopeptidase (AP) fraction from squid (Illex illecebrosus) hepatopancreas was added to Cheddar cheese at 2 levels, and its influence on ripening indices was determined for up to 3-mo storage at 11 °C. Two commercial enzymes (Neutrase ® and Flavourzyme ®) were similarly tested. Cheese with the higher level of squid AP contained more soluble N, amino acids, and Cheddar flavor after 1 mo, but it developed defects in texture and bitterness as ripening progressed. Cheese with less squid AP did not differ from the control with respect to all ripening indices over 3-mo storage. Ripening Cheddar contains cysteine protease inhibitor(s) that inhibit low levels of squid AP but not Neutrase ® and Flavourzyme ®.     

Accelerated Cheddar Cheese Ripening by Added Microbial Enzymes

Good quality medium sharp Cheddar cheeses with 3-mo curing at 10 C were produced when the following enzyme combinations and concentrations were used: fungal protease 31000 (Miles), .005% + fungal lipase-MY (Meito) .00005 to .0002%; and fungal protease P-53 (Rohm & Haas), .0035% + fungal lipase-MY (Meito), .00005 to .0002%.Cheddar cheeses treated with microbial enzymes developed higher soluble protein and free volatile fatty acids and displayed better flavor and greater acceptability than control cheeses. Added microbial proteases contributed to the breakdown of casein, especially β-casein. Also, αs₁-I casein and free amino acids were high in cheeses treated with protease. Increased rate of proteolysis in enzyme-treated cheese had a direct relation to accelerated ripening.     

Impact of nisin producing culture and liposome-encapsulated nisin on ripening of Lactobacillus added-Cheddar cheese

This study aimed to evaluate the effects of incorporating liposome-encapsulated nisin Z, nisin Z producing Lactococcus lactis ssp. lactis biovar. diacetylactis UL719, or Lactobacillus casei-casei L2A adjunct culture into cheese milk on textural, physicochemical and sensory attributes during ripening of Cheddar cheese. For this purpose, cheeses were made using a selected nisin tolerant cheese starter culture. Proteolysis, free fatty acid production, rheological parameters and hydrophilic/hydrophobic peptides evolution were monitored over 6 mo ripening. Sensory quality of cheeses was evaluated after 6 mo. Incorporating the nisin-producing strain into cheese starter culture increased proteolysis and lipolysis but did not significantly affect cheese rheology. Liposome-encapsulated nisin did not appear to affect cheese proteolysis, rheology and sensory characteristics. The nisinogenic strain increased the formation of both hydrophilic and hydrophobic peptides present in the cheese water extract. Sensory assessment indicated that acidic and bitter tastes were enhanced in the nisinogenic strain-containing cheese compared to control cheese. Incorporating Lb. casei and the nisinogenic culture into cheese produced a debittering effect and improved cheese flavor quality. Cheeses with added Lb. casei and liposome-encapsulated nisin Z exhibited the highest flavor intensity and were ranked first for sensory characteristics.     

The effects of using a starter culture,lipase, and protease enzymes on ripening of Mihalic cheese

The purpose of this study was to determine the effects of fungal lipase from Mucor miehei and a bacterial neutral protease from Bacillus subtilis alone and combined with a starter culture on ripening properties of traditional Turkish Mihalic cheese. The use of protease with lipase (Cult + Prot + Lip) resulted in better flavour and texture with accelerated ripening. The obtained results pointed out that the gross compositions of the cheeses were changed by the type of enzymes and ripening time (P < 0.01). The acid degree value (ADV) of all cheeses showed a linear increase with ripening. The highest lipolysis rate was noted in lipase‐added cheese batch (as 5.56 ADV) with highest γ‐CN ratio and β‐CN degradation. At the end of ripening time, it was observed that αs‐CN ratios decreased in starter‐added (Cult), starter + protease–added (Cult + Prot), and protease‐added (Prot) cheese batches. The use of protease with lipase (Cult + Prot + Lip) resulted in better flavour and texture with accelerated ripening. Protease‐added cheeses, which were characterized by bitterness and crumbly textural properties owing to the intense breakdown of β‐casein, scored lower than lipase‐added cheeses. It was determined that the use of mesophilic aromatic starter culture with lipase and protease could be used to accelerate ripening of Mihalic cheese made from pasteurised milk.     

Determination of regional flavor differences in U.S. Cheddar cheeses aged for 6 mo or longer

ABSTRACT:  Cheddar cheese is a widely popular food in the United States. This product is produced in facilities across the United States and often marketed based on region of manufacture, implying that regional differences in flavor character of the cheese exist. This study was conducted to determine if regional differences in flavor exist in the aged U.S. Cheddar cheeses. Three times per year for 2 y, triplicate 18-kg blocks of Cheddar cheese (< 60 d old) were obtained from 19 manufacturing facilities located in 4 major cheese- producing regions/states: California, Northwest, Midwest, and Northeast. A trained sensory panel documented the flavor characteristics of cheeses after 6-, 9-, 12-, 18-, and 24-mo ripening at 7 °C. Regional differences were observed for specific flavors for cheeses manufactured in the Northwest, Midwest, and Northeast across ripening ( P < 0.05), but the specific flavors responsible for these effects were not consistent across ripening. Similarly, cheese make procedure effects were also observed for specific flavors across ripening ( P < 0.05), but these differences were also not consistent across ripening. The impact of region and cheese make procedure on flavor of the aged Cheddar cheeses was small in comparison to consistently documented, facility-specific flavor differences ( P < 0.0001). Flavor profiles of aged Cheddar cheeses were most strongly influenced by practices specific to manufacturing facility rather than region of manufacture.     

Application of encapsulated enzymes to accelerate cheese ripening

The suitability of gellan, κ-carrageenan and a high-melting-fat-fraction of milk fat (HMFF) to encapsulate protease enzymes (Flavourzyme) and impact in accelerating Cheddar cheese ripening were studied. The rates of enzyme entrapment were 48.2%, 55.6%, and 38.9% for gellan, κ-carrageenan and HMFF, respectively. The enzyme capsules were incorporated into milk during cheese manufacture. The moisture content of cheeses with added gum capsules was higher than control cheeses. Casein (β) degradation was monitored by High-Performance Capillary Electrophoresis. All cheeses treated with encapsulated enzyme showed higher rates of proteolysis than the control cheese throughout the ripening period. The rate of proteolysis was greater with cheeses made incorporating κ-carrageenan capsules containing protease. Cheese texture and sensory quality were not significantly influenced by the type of encapsulating material (gum or milk fat). Differences in textural and sensory quality between treated and control cheeses were consistent with release of protease enzymes from capsules.     

Evidence of a relationship between autolysis of starter bacteria and lipolysis in cheddar cheese during ripening

Cell viability, autolysis and lipolysis were studied in Cheddar cheese made using Lactococcus lactis subsp. cremoris AM2 or Lactococcus lactis subsp. cremoris HP. Cheddar cheese was made in triplicate over a 3 month period and ripened for 238 days at 8 degrees C. Cell viability in cheese was lower for AM2 (a non-bitter strain) than for strain HP (a bitter strain). Autolysis, monitored by the level of the intracellular marker enzyme, lactate dehydrogenase (EC 1.1.1.27) in cheese 'juice' extracted by hydraulic pressure, was much greater in the cheese made using AM2 than that made with HP. Lipolysis was determined by the increase during ripening of individual free fatty acids (FFA) from butyric (C4:0) to linolenic acid (C18:3) measured using a high performance liquid chromatographic technique. Levels of individual FFA from butyric (C4:0) to linolenic (C18:3) acids increased significantly (P<0.05) during ripening in cheeses made with either starter culture. Palmitic (C16:0) and oleic (C18:1) acids were the most abundant FFA throughout ripening in all cheeses. Levels of caprylic (C8:0), myristic (C14:0), palmitic (C16:0) and stearic (C18:0) acids were significantly higher (P<0.05) in cheeses manufactured with Lc. lactis subsp. cremoris AM2 than in cheeses manufactured with Lc. lactis subsp. cremoris HP. Differences in levels of lipolysis between strains was not due to differences in the specific lipolytic or esterolytic activities in cell free extracts of the strains as measured by activity on triolein (lipase) and p-nitrophenylbutyrate (esterase) substrates. Therefore, evidence is provided for a relationship between the extent of starter cell autolysis and the level of lipolysis during Cheddar cheese ripening.     

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.     

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.     

Impact of fat reduction on flavor and flavor chemistry of Cheddar cheeses

A current industry goal is to produce a 75 to 80% fat-reduced Cheddar cheese that is tasty and appealing to consumers. Despite previous studies on reduced-fat cheese, information is critically lacking in understanding the flavor and flavor chemistry of reduced-fat and nonfat Cheddar cheeses and how it differs from its full-fat counterpart. The objective of this study was to document and compare flavor development in cheeses with different fat contents so as to quantitatively characterize how flavor and flavor development in Cheddar cheese are altered with fat reduction. Cheddar cheeses with 50% reduced-fat cheese (RFC) and low-fat cheese containing 6% fat (LFC) along with 2 full-fat cheeses (FFC) were manufactured in duplicate. Cheeses were ripened at 8°C and samples were taken following 2 wk and 3, 6, and 9 mo for sensory and instrumental volatile analyses. A trained sensory panel (n = 10 panelists) documented flavor attributes of cheeses. Volatile compounds were extracted by solid-phase microextraction or solvent-assisted flavor evaporation followed by separation and identification using gas chromatography-mass spectrometry and gas chromatography-olfactometry. Selected compounds were quantified using external standard curves. Sensory properties of cheeses were distinct initially but more differences were documented as cheeses aged. By 9 mo, LFC and RFC displayed distinct burnt/rosy flavors that were not present in FFC. Sulfur flavor was also lower in LFC compared with other cheeses. Forty aroma-active compounds were characterized in the cheeses by headspace or solvent extraction followed by gas chromatography-olfactometry. Compounds were largely not distinct between the cheeses at each time point, but concentration differences were evident. Higher concentrations of furanones (furaneol, homofuraneol, sotolon), phenylethanal, 1-octen-3-one, and free fatty acids, and lower concentrations of lactones were present in LFC compared with FFC after 9 mo of ripening. These results confirm that flavor differences documented between full-fat and reduced-fat cheeses are not due solely to differences in matrix and flavor release but also to distinct differences in ripening biochemistry, which leads to an imbalance of many flavor-contributing compounds.     

The effect of application of cold natural smoke on the ripening of Cheddar cheese

The present study was undertaken to study the effects of application of natural wood smoke on ripening of Cheddar cheese, and to determine the effects of smoking before or after ripening on cheese quality. A 20-kg block of Cheddar cheese obtained immediately after pressing was divided into six approximately 3-kg blocks and ripened at 8 degrees C for up to 270 d. One 3-kg block was taken after 1 d, 1, 3, 6, or 9 mo and smoked for 20 min, then returned to the ripening room for further ripening. Cheeses were sampled at intervals for lactobacilli counts, moisture, pH, and proteolysis. Sensory analysis was conducted on 6 and 9-mo-old cheeses by a trained sensory panel (n = 7). Results show that application of natural wood smoke did not significantly affect cheese pH or primary proteolysis during ripening. However, secondary proteolysis as assessed by the concentrations of free amino acids was generally higher in smoked cheeses than in control cheeses after 6 mo of ripening. Cheese smoked after 6 mo of ripening had better smoked flavor than that smoked after 9 mo of ripening. Cheese smoked after 3 mo of age and further ripened for 6 mo had the highest smoked flavor intensity. It is concluded that it is best to smoke cheese after ripening for at least 3 mo.     

基于快速成熟模型的藏灵菇发酵切达干酪挥发性风味物质分析

通过建立快速成熟干酪模型,采用固相微萃取法提取传统藏灵菇发酵的切达干酪模型与商品发酵剂制作的切达干酪模型中挥发性成分,并结合气相色谱-质谱联用技术和气相色谱-嗅闻技术对萃取成分进行鉴定,结果表明醇类和酯类是藏灵菇发酵切达干酪成熟过程中的主要风味物质。藏灵菇发酵切达干酪模型中风味物质的种类和含量都明显高于商业发酵剂制作的切达干酪模型,其中酯类物质的变化最为显著。感官评价和风味分析结果表明,藏灵菇发酵切达干酪模型中酯类和醇类物质种类和含量更为丰富,风味更强,水果香味更浓郁,还具有酒香味。     

Evolution of Free Amino Acids during the Ripening of Cheddar Cheese Containing Added Lactobacilli Strains

Cheddar cheese was produced with different lactobacilli strains added to accelerate ripening. The concentration of proteolytic products was determined as free amino acids in the water-soluble fraction at two, four, seven and nine months of aging and at two different maturation temperatures (6°C, 15°C). All amino acids increased during ripening and were higher in the Lactobacillus- added cheeses than in the control cheese, and higher in cheeses ripened at 15°C than at 6°C. Glutamic acid, leucine, phenylalanine, valine and lysine were generally in higher proportion in all cheeses. The cheeses with added L. casei-casei L2A were classified as having a “strong Cheddar cheese” flavor after only seven months of ripening at 6°C.     

Free fatty acid content of Manchego-type cheese salted by brine vacuum impregnation

A new salting method based on the brine vacuum impregnation of porous products was tested in Manchego-type cheese in order to assess its effect on cheese lipolysis during ripening. This new salting method would allow a faster salt diffusion and a more homogeneous initial salt distribution, and would reduce the disposal of brine. Salt-in-moisture content was evaluated in three different cheese zones during a 90-day ripening period in order to monitor salt penetration in the cheese. Lipolysis was evaluated by means of gas chromatography of individual free fatty acids in the medium and internal zones of both cheeses salted by the conventional and the new salting procedures. Free fatty acid concentration regularly increased during ripening. Short-chain free fatty acid content was higher in the internal zone of conventionally salted cheeses than in the internal and medium zones of vacuum impregnated cheeses from the first month after manufacturing, probably due to the low initial salt concentration achieved in the inner zone of conventionally salted cheeses, which can enhance both bacterial and indigenous lipase activity. Panelists considered that conventionally salted cheeses presented a more intense aroma than vacuum impregnated cheeses, though no differences in global flavor intensity were observed.     

Antioxidant activity of Cheddar cheeses at different stages of ripening

The aim of the study was to evaluate the changes in the antioxidant properties of Cheddar cheese at different stages of ripening using different assays: 2, 2'-azinobis (3 ethyl benzothiazoline)-6-sulphonic acid, 2, 2-diphenyl 1, picryl hydrazyl and superoxide radical scavenging activity. Cheddar cheese was prepared with Lactobacillus casei ssp. casei 300 and Lactobacillus paracasei ssp. paracasei 22 and without adjunct cultures. The antioxidant activity of water-soluble extracts of Cheddar cheese was dependent on the ripening period. The changes in the antioxidant activity were related to the rate of formation of soluble peptides (proteolysis) in all the samples of cheeses up to fourth month of ripening.     

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.