1. Defects

Common Cheese Defects

Body: in the context of modern sensory analysis, body refers to texture, which is confusing because cheese graders use the term “texture” to refer to cheese openness. Here, we will use the traditional cheese grading terms. Some descriptors for body defects are:

• Crumbly/short: often due to excess salt or acid.
• Corky: due to overcooking, low fat, low moisture, or excess salt.
• Mealy: this defect can be detected on the palate or by massaging the cheese between the thumb and forefinger. It is usually associated with excess acidity.
• Pasty: sticks to the palate and fingers; due to excess moisture.
• Weak: breaks down too quickly when worked by hand due to excess fat or moisture.

Texture: relates to openness in the cheese which may or may not be desirable depending on the type of cheese and the cause of openness. Openness can be due to:

• Mechanical openings, which are holes of irregular shape caused by trapped whey. Trapped whey makes the impression in the cheese during pressing, but during ripening the moisture is dispersed throughout the cheese leaving the hole behind. Mechanical openings can lead to discolouration around the opening due to local acid development. Undesired mechanical openings can be reduced or closed by vacuum packaging.
• Gas holes, which are desirable in many types of cheese. Gas hole defects include:
  • Early gas defects due to coliforms. These appear as small, spherical, shiny holes. The defect is often associated with unclean flavour.
  • Late gas due to Clostridium tyrobutryricum or perfringens, especially in some European made cheese. Clostridia spores are often present in American cheese as well but do not normally cause problems. However, they may be activated by heat treatment and therefore, sometimes cause gas defect in processed cheese.
  • A third gas defect occurs in Cheddar and American types. The defect is distinctive in that the gas (mainly CO₂ with some hydrogen sulphide) blows the package but not the cheese. The defect occurs at 6 – 9 months in Cheddar, but a similar defect is sometimes observed earlier in American Mozzarella and Colby. The causative anaerobic organism is not fully identified; however, experiments have demonstrated that the defect does not occur in cheese aged at < 10°C.
  • Yeast slits due to yeast growth.

Flavour: most grading systems assign the greatest weight to flavour defects. A few common descriptors are:

• Acid flavour is often associated with acid body defects noted above. The common causes all relate to process control:
  • Too much moisture (i.e., too much lactose).
  • Too much starter (i.e., too much acid development before draining).
  • Salting too late or too little.
  • Too warm during or immediately after pressing.
• Bitter flavours are common defects in American but also other cheese, including fresh cheese. Some causes include:
  • High moisture
  • Excess rennet
  • Bitter cultures
  • High ripening temperatures
• Fruity/Yeasty flavours are usually associated with high pH and bitterness, and sometimes with yeast slits.
• Unclean flavours are reminiscent of the barnyard, and may be associated with coliforms.
• Whey taint is due to high moisture and is usually associated with acid defects including bitterness.

Colour: other than traditional colour preferences, such as orange Cheddar and white goat cheese, the most important colour parameter is uniformity. Even for cheese such as Colby, which is coloured with annatto, graders do not evaluate colour intensity. Rather, they look for non-uniformity, which may signal a manufacturing defect. Some common descriptors are:

• Acid cut (pink or bleached): low pH, oxidation of annatto.
  

  

• Mottled: may be an acid defect or caused by mixing cheese from different vats.
• Seamy: this is a Cheddar defect where the curd particles fail to knit properly. Causes Include:
  • Greasy curd from too much fat or high temperature during pressing.
  • Improper salting, too soon after milling or pH at salting is too high or too low.
  • Hooped too soon after salting.

Finish: a lot of art and patience are required to produce cheese with a good finish. Common defects are:

• Checked/Cracked: too dry on surface.
• Greasy: temperature too high during pressing or curing.
• Huffed: gassy.
• Mineral Deposits due to calcium lactate.
  • Common on Cheddar cheese and sometimes on American varieties
  • Encouraged by certain non-starter Lactobacilli and Pediococci which favour formation of D-lactate which in turn encourages crystallization of DL-calcium lactate.
  • Control measures are:
    • Decrease numbers of non-starter bacteria (e.g., pasteurize versus heat treat and/or bactofuge the milk).
    • Use tight packaging. Calcium lactate crystals tends to form in areas where the package is loose or in depressions on the cheese surface.
    • Avoid temperature fluctuations. Calcium lactate crystals often form in the dairy case where temperatures are not constant.
    • Encourage rapid turnover in the dairy case.
• Rind rot caused by mites or mold.
• Surface mold is definitely one of the most common defects. A frequent consumer question is about the safety of moldy cheese.
• Unsymmetrical/Rough: poor workmanship.

2. Grading

The following cheese grading score sheets are adapted from the American Cheese Society and are included as examples only. Tables 16.1 and 16.2 show the glossaries of the respective technical and aesthetic grading terminology and descriptors used to grade cheese for the 2018 Canadian Cheese Awards, with definitions adapted from the American Cheese Society. Figures 16.1 and 16.2 are two parts of a single score card. Both of these score cards are defect-based evaluation, where the judge starts with a maximum score for each category and deducts points for each identified defect. Currently, many cheese competitions have Aesthetic and Technical judges working in teams, as in the score card example of Figure 16.1 and 16.2. Aesthetic judges add points for desirable properties (Figure 16.1); and Technical judges deduct points for defects (Figure 16.2). The two scores are summed to give a total score out of 100.

Table 16.1: Glossary of Terms for Judging Cheese

Terms with a parenthesis are specific for those cheese categories listed in the ( ), where:
F = Fresh, FL = Flavoured, BR = Bloomy rind, BC = Blue cheese

American Cheese Society, Stephanie Clark, Craig Gile, Vince Razionale, Bill Rufenacht, and Sarah Spira, eds. American Cheese Society Cheese and Dairy Product Lexicon and Glossary. Denver: American Cheese Society. Version 1 Published February 1, 2018.; Wisconsin Statute. Cheese Grading, Packaging, and Labelling, ATCP 81.01 35.93 §. Accessed January 3, 2018. Available at: https://docs.legis.wisconsin.gov/code/admin_code/atcp/055/81.

Table 16.2 Glossary of Terminology for Aesthetic Cheese Judging at the 2018 Cheese Awards

Terms with a parenthesis are specific for those cheese categories listed in the ( ), where:
F = Fresh, FL = Flavoured, BR = Bloomy rind, BC = Blue cheese

American Cheese Society, Stephanie Clark, Craig Gile, Vince Razionale, Bill Rufenacht, and Sarah Spira, eds. American Cheese Society Cheese and Dairy Product Lexicon and Glossary. Denver: American Cheese Society. Version 1 Published February 1, 2018; Wisconsin Statute. Cheese Grading, Packaging, and Labelling, ATCP 81.01 35.93 §. Accessed January 3, 2018. Available at: https://docs.legis.wisconsin.gov/code/admin_code/atcp/055/81.

Notes:

1. Cheese should be held overnight at 14.5 – 15.5°C before grading.
2. Cheese samples should be 9 Kg in weight.
3. Cheese should be at least 21 days old before grading.
4. Early evaluation of aging potential can be obtained by grading a sample stored at 15°C for 21 days.

Common Descriptors used in Grading Canadian Cheddar Cheese

1. Sl. open, sl. stiff, sl. coarse, blurred branding, sl. damp end, sl moldy surface.
2. As above plus slight acid tendency.
3. Weak, open, coarse, wet ends, sl. acid, sl. gas or pin holes, mottled colour etc.
4. Checked rinds with mold penetration. Sl. gas or pin holes. Any above defect plus a second defect except weak and open.
5. Very weak, very acidy, very stiff, very open, gas or Swiss holes (always 3rd), very uneven colour, very mottled.
6. Checked rinds, mold penetration, gas or Swiss holes (always 3rd).

Figures 16.1 and 16.2 below show a technical cheese judging score card. The technical score judging card is similar to the traditional defect based grading, which deducts points for defects in each category. Most current cheese judging employs both a technical and an aesthetic judge. The technical judge sums the points for each category to obtain a total score out of 50. This score is then added to the aesthetic score (see Figure 16.1) for a total score out of 100.

When defects are detected, points are deducted. The main categories for scoring are aroma, which yields 3 points maximum, flavour, which yields 25 points maximum, texture and body, which yields 15 points maximum, and lastly, appearance and rind development, which yields 7 points maximum. Under the category of aroma, the defects include: rancid, unclean, moldy or musty, cheese lacking aroma, animal or barnyard, unpleasant earth aroma, ammoniated, fruity or fermented, chemical aroma, and yeasty. Under the category of flavour, defects include: too acidic, lacks freshness, bitter, lacks characteristic flavour, fruity/fermented, old milk, feedy, rancid/lipase, flat, unclean, whey taint, lacks salt, yeasty, too salty, and excess or lacks flavour. Under the category of texture and body, defects include: crumbly, spreadability, curdy, weak, gassy, woody/tough, mealy, too open, pasty, grainy, pin holes, gummy, short, and lacks creaminess. Under the appearance and rind development category, defects include: cracked or disturbed rind, slipped rind, excessive rind, dull colour, rind rot, uneven mold distribution, immature mold, rough surface, greasy rind, uneven block, crooked/lopsided, whey stain, leaking with free moisture, calcium lactate crystals, surface mold, uneven shape, uneven colour, loose packaging, seamy, and uneven distribution of condiments. At the bottom of the sheet, there is an area for graders to provide overall comments to help the cheesemaker. There is also an area to put the total score.