Colorants in cheese manufacture: Production, chemistry, interactions, and regulation

Colored Cheddar cheeses are prepared by adding an aqueous annatto extract (norbixin) to cheese milk; however, a considerable proportion (∼20%) of such colorant is transferred to whey, which can limit the end use applications of whey products. Different geographical regions have adopted various strategies for handling whey derived from colored cheeses production. For example, in the United States, whey products are treated with oxidizing agents such as hydrogen peroxide and benzoyl peroxide to obtain white and colorless spray-dried products; however, chemical bleaching of whey is prohibited in Europe and China. Fundamental studies have focused on understanding the interactions between colorants molecules and various components of cheese. In addition, the selective delivery of colorants to the cheese curd through approaches such as encapsulated norbixin and microcapsules of bixin or use of alternative colorants, including fat-soluble/emulsified versions of annatto or beta-carotene, has been studied. This review provides a critical analysis of pertinent scientific and patent literature pertaining to colorant delivery in cheese and various types of colorant products on the market for cheese manufacture, and also considers interactions between colorant molecules and cheese components; various strategies for elimination of color transfer to whey during cheese manufacture are also discussed.

Solvent-mediated pressure-treated bixin-casein complexation for targeted color delivery

Carryover color in the whey fluid is one of the major challenges faced by the cheese manufacturing industry. In this study, we describe a solvent-mediated high-pressure process to complexate bixin and casein micelles as a novel strategy for color delivery. High pressures (120 and 240 MPa) and added ethanol resulted in change in casein hydrophobicity by exposure of tryptophan residues, as confirmed by spectroscopic methods. The incorporation of bixin resulted in a marked quenching of the fluorescence peak associated with tryptophan. A simulated coagulation study has shown that pressure-treated complexes resulted in whey powder with significantly lower a^* values than unbleached whey, whereas no significant differences were observed for b^* values. The results suggest that complexes can produce curds with a color similar to that using commercial annatto powder and whey powder with equal or superior color quality than obtained with chemical bleaching.

A 100-Year Review: Cheese production and quality

In the beginning, cheese making in the United States was all art, but embracing science and technology was necessary to make progress in producing a higher quality cheese. Traditional cheese making could not keep up with the demand for cheese, and the development of the factory system was necessary. Cheese quality suffered because of poor-quality milk, but 3 major innovations changed that: refrigeration, commercial starters, and the use of pasteurized milk for cheese making. Although by all accounts cold storage improved cheese quality, it was the improvement of milk quality, pasteurization of milk, and the use of reliable cultures for fermentation that had the biggest effect. Together with use of purified commercial cultures, pasteurization enabled cheese production to be conducted on a fixed time schedule. Fundamental research on the genetics of starter bacteria greatly increased the reliability of fermentation, which in turn made automation feasible. Demand for functionality, machinability, application in baking, and more emphasis on nutritional aspects (low fat and low sodium) of cheese took us back to the fundamental principles of cheese making and resulted in renewed vigor for scientific investigations into the chemical, microbiological, and enzymatic changes that occur during cheese making and ripening. As milk production increased, cheese factories needed to become more efficient. Membrane concentration and separation of milk offered a solution and greatly enhanced plant capacity. Full implementation of membrane processing and use of its full potential have yet to be achieved. Implementation of new technologies, the science of cheese making, and the development of further advances will require highly trained personnel at both the academic and industrial levels. This will be a great challenge to address and overcome.

Annatto-entrapped casein-chitosan complexes improve whey color quality after acid coagulation of milk

A fraction of annatto is often transferred to the whey fluid during Cheddar cheese processing, which negatively impacts the visual and sensory attributes of the resultant whey powder. Alternatives to reduce the color in the powder are still needed. In this study, casein-chitosan complexes were prepared to deliver annatto preferentially to the curd and reduce the amount of carryover colorant in whey powder. These complexes were relatively spherical, with a mean complex diameter of 8.3 ± 1.9 µm, zeta-potential of +39.4 ± 1.3 mV, and entrapment efficiency of 38.2 ± 3.1%. FT-IR spectroscopy confirmed the electrostatic interaction between casein and chitosan. Complexes and commercial annatto powder were incorporated into homogenized, reduced-fat, and fat-free milk, and subjected to acid coagulation. Whey powder produced from casein-chitosan-complex-treated samples exhibited better color quality than that prepared with annatto powder, indicating that the approach considered in this study was efficient in preventing the migration of colorant to the whey.

Flavor and Functional Characteristics of Whey Protein Isolates from Different Whey Sources

This study evaluated flavor and functional characteristics of whey protein isolates (WPIs) from Cheddar, Mozzarella, Cottage cheese, and rennet casein whey. WPIs were manufactured in triplicate. Powders were rehydrated and evaluated in duplicate by descriptive sensory analysis. Volatile compounds were extracted by solid-phase microextraction followed by gas chromatography-mass spectrometry. Functional properties were evaluated by measurement of foam stability, heat stability, and protein solubility. WPI from Cheddar and Cottage cheese whey had the highest cardboard flavor, whereas sweet aromatic flavor was highest in Mozzarella WPI, and rennet casein WPI had the lowest overall flavor and aroma. Distinct sour taste and brothy/potato flavor were also noted in WPI from Cottage cheese whey. Consistent with sensory results, aldehyde concentrations were also highest in Cheddar and Cottage cheese WPI. Overrun, yield stress, and foam stability were not different (P > 0.05) among Cheddar, Mozzarella, and rennet casein WPI, but WPI foams from Cottage cheese whey had a lower overrun and air-phase fraction (P < 0.05). Cottage cheese WPI was more heat stable at pH 7 (P < 0.05) than other WPI in 4% protein solutions, and was the only WPI to not gel at 10% protein. Cottage cheese WPI was less soluble at pH 4.6 compared to other WPI (P < 0.05) and also exhibited higher turbidity loss at pH 3 to 7 compared to other WPI (P < 0.05). This study suggests that WPI produced from nontraditional whey sources could be used in new applications due to distinct functional and flavor characteristics.

Desenvolvimento, caracterização e análise sensorial de formulações alimentares com proteínas do soro de leite ou albumina para crianças

O presente trabalho visou verificar a elaboração, a caracterização e a avaliação da aceitação de duas formulações alimentares achocolatadas (uma contendo albumina e a outra, concentrado proteico de soro de leite - WPC) para crianças de 7 a 10 anos. O desenvolvimento das formulações baseou-se nas recomendações nutricionais para a faixa etária. Foram avaliados os seguintes parâmetros físico-químicos: composição química, estabilidade, pH, viscosidade e fluidez. A análise sensorial englobou as escalas hedônica de atitude, intenção de consumo e doçura e foi realizada por um grupo de 142 julgadores de um centro universitário, com média de 24,5 ± 7,3 anos de idade e 66,2% do sexo feminino. Todos os dados obtidos foram submetidos à análise estatística, adotando-se p < 0,05 como nível de significância. A composição química não diferiu em base seca (p > 0,05). Observaram-se 3,88 (albumina) e 4,79 (WPC) vezes mais proteínas em 100 mL de amostra do que em bebidas comerciais. A primeira formulação mostrou-se mais viscosa (137,33 cP versus 22,33 cP da formulação com WPC) e menos fluida (percorreu 40 mL em 69 segundosversus 29 segundos da formulação com WPC). Quanto ao pH, o produto com albumina apresentou característica alcalina (8,60) e o com WPC ácida (6,28). Ambas as formulações permaneceram estáveis e homogêneas após 24 horas de visualização. A análise sensorial mostrou que as formulações foram similares em todos os testes aplicados (p > 0,05), sendo que as características mais bem avaliadas foram o sabor, a textura e a doçura, para ambas. Houve boa aceitação das formulações, com nota mediana de 7 e valores acima de 80% para a soma das respostas positivas nos testes. Conclui-se que as formulações alimentares analisadas apresentaram boas características físico-químicas e mostraram-se equilibradas nutricionalmente, com potencial para comercialização.

The effect of acidification of liquid whey protein concentrate on the flavor of spray-dried powder

Off-flavors in whey protein negatively influence consumer acceptance of whey protein ingredient applications. Clear acidic beverages are a common application of whey protein, and recent studies have demonstrated that beverage processing steps, including acidification, enhance off-flavor production from whey protein. The objective of this study was to determine the effect of preacidification of liquid ultrafiltered whey protein concentrate (WPC) before spray drying on flavor of dried WPC. Two experiments were performed to achieve the objective. In both experiments, Cheddar cheese whey was manufactured, fat-separated, pasteurized, bleached (250 mg/kg of hydrogen peroxide), and ultrafiltered (UF) to obtain liquid WPC that was 13% solids (wt/wt) and 80% protein on a solids basis. In experiment 1, the liquid retentate was then acidified using a blend of phosphoric and citric acids to the following pH values: no acidification (control; pH 6.5), pH 5.5, or pH 3.5. The UF permeate was used to normalize the protein concentration of each treatment. The retentates were then spray dried. In experiment 2, 150 μg/kg of deuterated hexanal (D₁₂-hexanal) was added to each treatment, followed by acidification and spray drying. Both experiments were replicated 3 times. Flavor properties of the spray-dried WPC were evaluated by sensory and instrumental analyses in experiment 1 and by instrumental analysis in experiment 2. Preacidification to pH 3.5 resulted in decreased cardboard flavor and aroma intensities and an increase in soapy flavor, with decreased concentrations of hexanal, heptanal, nonanal, decanal, dimethyl disulfide, and dimethyl trisulfide compared with spray drying at pH 6.5 or 5.5. Adjustment to pH 5.5 before spray drying increased cabbage flavor and increased concentrations of nonanal at evaluation pH values of 3.5 and 5.5 and dimethyl trisulfide at all evaluation pH values. In general, the flavor effects of preacidification were consistent regardless of the pH to which the solutions were adjusted after spray drying. Preacidification to pH 3.5 increased recovery of D₁₂-hexanal in liquid WPC and decreased recovery of D₁₂-hexanal in the resulting powder when evaluated at pH 6.5 or 5.5. These results demonstrate that acidification of liquid WPC80 to pH 3.5 before spray drying decreases off-flavors in spray-dried WPC and suggest that the mechanism for off-flavor reduction is the decreased protein interactions with volatile compounds at low pH in liquid WPC or the increased interactions between protein and volatile compounds in the resulting powder.

Short communication: norbixin and bixin partitioning in Cheddar cheese and whey

The Cheddar cheese colorant annatto is present in whey and must be removed by bleaching. Chemical bleaching negatively affects the flavor of dried whey ingredients, which has established a need for a better understanding of the primary colorant in annatto, norbixin, along with cheese color alternatives. The objective of this study was to determine norbixin partitioning in cheese and whey from full-fat and fat-free Cheddar cheese and to determine the viability of bixin, the nonpolar form of norbixin, as an alternative Cheddar cheese colorant. Full-fat and fat-free Cheddar cheeses and wheys were manufactured from colored pasteurized milk. Three norbixin (4% wt/vol) levels (7.5, 15, and 30 mL of annatto/454 kg of milk) were used for full-fat Cheddar cheese manufacture, and 1 norbixin level was evaluated in fat-free Cheddar cheese (15 mL of annatto/454 kg of milk). For bixin incorporation, pasteurized whole milk was cooled to 55 °C, and then 60 mL of bixin/454 kg of milk (3.8% wt/vol bixin) was added and the milk homogenized (single stage, 8 MPa). Milk with no colorant and milk with norbixin at 15 mL/454 kg of milk were processed analogously as controls. No difference was found between the norbixin partition levels of full-fat and fat-free cheese and whey (cheese mean: 79%, whey: 11.2%). In contrast to norbixin recovery (9.3% in whey, 80% in cheese), 1.3% of added bixin to cheese milk was recovered in the homogenized, unseparated cheese whey, concurrent with higher recoveries of bixin in cheese (94.5%). These results indicate that fat content has no effect on norbixin binding or entrapment in Cheddar cheese and that bixin may be a viable alternative colorant to norbixin in the dairy industry.