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1.
J Dairy Sci ; 102(10): 8768-8784, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31351721

RESUMO

Acid whey resulting from the production of soft cheeses is a disposal problem for the dairy industry. Few uses have been found for acid whey because of its high ash content, low pH, and high organic acid content. The objective of this study was to explore the potential of recovery of whey protein from cottage cheese acid whey for use in yogurt. Cottage cheese acid whey and Cheddar cheese whey were produced from standard cottage cheese and Cheddar cheese-making procedures, respectively. The whey was separated and pasteurized by high temperature, short time pasteurization and stored at 4°C. Food-grade ammonium hydroxide was used to neutralize the acid whey to a pH of 6.4. The whey was heated to 50°C and concentrated using ultrafiltration and diafiltration with 11 polyethersulfone cartridge membrane filters (10,000-kDa cutoff) to 25% total solids and 80% protein. Skim milk was concentrated to 6% total protein. Nonfat, unflavored set-style yogurts (6.0 ± 0.1% protein, 15 ± 1.0% solids) were made from skim milk with added acid whey protein concentrate, skim milk with added sweet whey protein concentrate, or skim milk concentrate. Yogurt mixes were standardized to lactose and fat of 6.50% and 0.10%, respectively. Yogurt was fermented at 43°C to pH 4.6 and stored at 4°C. The experiment was replicated in triplicate. Titratable acidity, pH, whey separation, color, and gel strength were measured weekly in yogurts through 8 wk. Trained panel profiling was conducted on 0, 14, 28, and 56 d. Fat-free yogurts produced with added neutralized fresh liquid acid whey protein concentrate had flavor attributes similar those with added fresh liquid sweet whey protein but had lower gel strength attributes, which translated to differences in trained panel texture attributes and lower consumer liking scores for fat-free yogurt made with added acid whey protein ingredient. Difference in pH was the main contributor to texture differences, as higher pH in acid whey protein yogurts changed gel structure formation and water-holding capacity of the yogurt gel. In a second part of the study, the yogurt mix was reformulated to address texture differences. The reformulated yogurt mix at 2% milkfat and using a lower level of sweet and acid whey ingredient performed at parity with control yogurts in consumer sensory trials. Fresh liquid acid whey protein concentrates from cottage cheese manufacture can be used as a liquid protein ingredient source for manufacture of yogurt in the same factory.


Assuntos
Ingredientes de Alimentos , Proteínas do Leite , Proteínas do Soro do Leite , Iogurte , Animais , Queijo/análise , Fermentação , Manipulação de Alimentos/métodos , Leite/química , Proteínas do Leite/análise , Pasteurização , Paladar , Soro do Leite/química , Proteínas do Soro do Leite/química , Iogurte/análise
2.
J Dairy Sci ; 102(3): 2022-2043, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30612790

RESUMO

Our goal was to determine the effect of pasteurization-homogenization, fat and protein concentration, proportion of milk protein that is casein and serum protein, and temperature on sensory and instrumental measures of viscosity and color of milk-based beverages. A second goal was to use instrumental measures of whiteness and yellowness to predict sensory measures of whiteness and yellowness. A complete balanced 3 factor (fat, true protein, and casein as a percentage of true protein) design was applied with 3 levels of fat (0.2, 1.0 and 2.0%), 4 levels of true protein (3.00, 3.67, 4.34, and 5.00%) within each fat level, and 5 levels of casein as a percentage of true protein (CN%TP; 5, 25, 50, 75, and 80%) within each protein level for beverage formulation. Instrumental color and viscosity, and visual sensory color analyses were done on each beverage formulation. For unpasteurized beverages across 3 fat levels (0.2, 1, and 2%), changes in CN%TP had the largest effect on L values, sensory whiteness, opacity, color intensity, and yellowness, whereas changes in fat concentration had a stronger influence on a and b* values. Increasing CN%TP from 5 to 80% increased L values, sensory whiteness, and opacity, and decreased sensory color intensity and yellowness. The a and b* values increased with increasing fat concentration. For unpasteurized milk protein beverages within each fat level, variation in CN%TP dominated the changes in L values, sensory whiteness, and opacity, and decreased a and b* values, sensory color intensity, and yellowness. The effect of heat (pasteurization and homogenization) and its interaction terms had the second largest effect on color of milk protein beverages with respect to instrumental color data and sensory appearance attributes. Heat increased L values, sensory whiteness, and opacity, and decreased a and b* values, sensory color intensity, and yellowness. Increases in temperature decreased instrumental viscosity and changes in protein concentration and CN%TP had a greater effect on instrument viscosity data within each temperature (4, 20, and 50°C) than fat. Sensory perception of yellowness was not highly correlated with b* values. Multiple linear regressions of L, a, and b* values produced more robust predictions for both sensory whiteness and yellowness than simple linear regression with L and b* values alone, and may be a useful instrumental approach for quality control of sensory whiteness and yellowness of milk protein beverages.


Assuntos
Proteínas Sanguíneas/análise , Caseínas/análise , Glicolipídeos/análise , Glicoproteínas/análise , Proteínas do Leite/análise , Pasteurização , Cor , Gotículas Lipídicas , Temperatura , Viscosidade
3.
J Dairy Sci ; 101(6): 4891-4905, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29573805

RESUMO

The objective of our work was to determine the differences in sensitivity of Hunter and International Commission on Illumination (CIE) methods at 2 different viewer angles (2 and 10°) for measurement of whiteness, red/green, and blue/yellow color of milk-based beverages over a range of composition. Sixty combinations of milk-based beverages were formulated (2 replicates) with a range of fat level from 0.2 to 2%, true protein level from 3 to 5%, and casein as a percent of true protein from 5 to 80% to provide a wide range of milk-based beverage color. In addition, commercial skim, 1 and 2% fat high-temperature, short-time pasteurized fluid milks were analyzed. All beverage formulations were HTST pasteurized and cooled to 4°C before analysis. Color measurement viewer angle (2 vs. 10°) had very little effect on objective color measures of milk-based beverages with a wide range of composition for either the Hunter or CIE color measurement system. Temperature (4, 20, and 50°C) of color measurement had a large effect on the results of color measurement in both the Hunter and CIE measurement systems. The effect of milk beverage temperature on color measurement results was the largest for skim milk and the least for 2% fat milk. This highlights the need for proper control of beverage serving temperature for sensory panel analysis of milk-based beverages with very low fat content and for control of milk temperature when doing objective color analysis for quality control in manufacture of milk-based beverages. The Hunter system of color measurement was more sensitive to differences in whiteness among milk-based beverages than the CIE system, whereas the CIE system was much more sensitive to differences in yellowness among milk-based beverages. There was little difference between the Hunter and CIE system in sensitivity to green/red color of milk-based beverages. In defining milk-based beverage product specifications for objective color measures for dairy product manufacturers, the viewer angle, color measurement system (CIE vs. Hunter), and sample measurement temperature should be specified along with type of illuminant.


Assuntos
Bebidas/análise , Análise de Alimentos/métodos , Leite/química , Animais , Caseínas/análise , Cor , Manipulação de Alimentos/métodos , Temperatura Alta , Pasteurização
4.
J Food Sci ; 75(9): S522-6, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-21535626

RESUMO

Appropriate nutrient-dense foods and beverages are crucial for children for proper growth and development and to develop healthful lifelong habits. This study investigated children's (ages 8 to 16 y old) perception of sensory intensity, attribute liking and overall liking of unflavored and chocolate lactose-free cow's milk and soy beverages. Products were not identified as to whether they were soy or milk. Children showed greater acceptance of lactose-free cow's milk compared to milk substitute beverages, within flavor category. No differences in acceptance emerged by ethnic group (Caucasian, African American, Hispanic), but a large difference emerged by age group. All product acceptance differences perceived by older children reoccurred among the younger children and in the same direction, but the older children used a larger range of numbers, especially at the lower end, rather than at the higher end of acceptance. The effect of age is not a simple scaling bias but may suggest a reduced criticism by younger respondents of less-acceptable products.


Assuntos
Leite , Percepção Olfatória , Leite de Soja , Inquéritos e Questionários , Percepção Gustatória , Adolescente , Negro ou Afro-Americano , Fatores Etários , Animais , Cacau/química , Criança , Ingestão de Energia , Hispânico ou Latino , Humanos , Entrevistas como Assunto , Paladar , População Branca
5.
J Agric Food Chem ; 56(17): 8096-102, 2008 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-18686969

RESUMO

Published research has indicated that ethyl 2-methylpropanoate, ethyl 2-methybutanaote, ethyl 3-methylbutanoate, hexanoic acid, butanoic acid, and 3-methylbutanoic acid are responsible for fruity fermented (FF) off-flavor; however, these compounds were identified in samples that were artificially created by curing immature peanuts at a constant high temperature. The objective of this study was to characterize the volatile compounds contributing to naturally occurring FF off-flavor. Volatile compounds of naturally occurring FF and no-FF samples were characterized using solvent-assisted flavor evaporation (SAFE), solid phase microextraction (SPME), gas chromatography-olfactometry (GC-O), and gas chromatography-mass spectrometry (GC-MS). Aroma extract dilution analysis (AEDA) identified 12 potent aroma active compounds, none of which were the previously identified esters, with no consistent differences among the aroma active compounds in no-FF and FF samples. Hexanoic acid alone was identified in the naturally occurring FF sample using the SAFE GC-MS methodology, whereas two of the three previously identified esters were identified in natural and artificially created samples. The same two esters were confirmed by SPME GC-MS in natural and artificially created samples. This study demonstrated the need for caution in the direct application of data from artificially created samples until those compounds are verified in natural samples. However, these results suggest that a laboratory method using SPME-GC techniques could be developed and correlated on an ester concentration versus FF intensity basis to provide an alternative to sensory analysis for detection of FF off-flavor in peanut lots.


Assuntos
Arachis/química , Fermentação , Sementes/química , Paladar , Frutas , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Odorantes/análise , Volatilização
6.
J Dairy Res ; 74(4): 468-77, 2007 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17961289

RESUMO

Four semi-hard Italian goats' milk cheeses, Flor di Capra (FC), Caprino di Cavalese (CC), Caprino di Valsassina (CV) and Capritilla (C), were compared for compositional, microbiological, biochemical, volatile profile and sensory characteristics. Mean values for the gross composition in part differed between cheeses. At the end of ripening, cheeses contained 7.98-8.51 log10 cfu/g of non-starter lactic acid bacteria. Lactobacillus paracasei, Lb. casei and Lb. plantarum were dominant in almost all cheeses. As shown by the Principal Component Analysis of RP-FPLC data for the pH 4.6-soluble fractions and by the determination of free amino acids, secondary proteolysis of CC and CV mainly differed from the other two cheeses. A total of 72 volatile components were identified by steam distillation-extraction followed by gas chromatography-mass spectrometry. Free fatty acids and esters qualitatively and quantitatively differentiated the profile of CV and CC, respectively. The lowest concentrations of volatile components characterized FC. Descriptive sensory analysis using 17 flavour attributes was carried out by a trained panel. Different flavour attributes distinguished the four goats' cheeses and relationships were found with volatile components, biochemical characteristics and technology.


Assuntos
Queijo/análise , Queijo/microbiologia , Paladar , Animais , Manipulação de Alimentos , Microbiologia de Alimentos , Cabras , Itália
7.
Appl Environ Microbiol ; 70(8): 4814-20, 2004 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-15294819

RESUMO

Metabolism of aromatic amino acids by lactic acid bacteria is an important source of off-flavor compounds in Cheddar cheese. Previous work has shown that alpha-keto acids produced from Trp, Tyr, and Phe by aminotransferase enzymes are chemically labile and may degrade spontaneously into a variety of off-flavor compounds. However, dairy lactobacilli can convert unstable alpha-keto acids to more-stable alpha-hydroxy acids via the action of alpha-keto acid dehydrogenases such as d-hydroxyisocaproic acid dehydrogenase. To further characterize the role of this enzyme in cheese flavor, the Lactobacillus casei d-hydroxyisocaproic acid dehydrogenase gene was cloned into the high-copy-number vector pTRKH2 and transformed into L. casei ATCC 334. Enzyme assays confirmed that alpha-keto acid dehydrogenase activity was significantly higher in pTRKH2:dhic transformants than in wild-type cells. Reduced-fat Cheddar cheeses were made with Lactococcus lactis starter only, starter plus L. casei ATCC 334, and starter plus L. casei ATCC 334 transformed with pTRKH2:dhic. After 3 months of aging, the cheese chemistry and flavor attributes were evaluated instrumentally by gas chromatography-mass spectrometry and by descriptive sensory analysis. The culture system used significantly affected the concentrations of various ketones, aldehydes, alcohols, and esters and one sulfur compound in cheese. Results further indicated that enhanced expression of d-hydroxyisocaproic acid dehydrogenase suppressed spontaneous degradation of alpha-keto acids, but sensory work indicated that this effect retarded cheese flavor development.


Assuntos
3-Metil-2-Oxobutanoato Desidrogenase (Lipoamida)/metabolismo , Caproatos/metabolismo , Queijo/microbiologia , Lacticaseibacillus casei/enzimologia , 3-Metil-2-Oxobutanoato Desidrogenase (Lipoamida)/genética , Caproatos/química , Meios de Cultura , Cromatografia Gasosa-Espectrometria de Massas , Lacticaseibacillus casei/genética , Lactococcus lactis/enzimologia , Lactococcus lactis/genética , Plasmídeos , Paladar
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