Special Issue "Structure and Flavour of Dairy Products"

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A special issue of Foods (ISSN 2304-8158).

Deadline for manuscript submissions: closed (31 October 2013)

Special Issue Editor

Guest Editor
Dr. David W. Everett (Website)

Dairy Products Technology Center, California Polytechnic State University 1 Grand Avenue, San Luis Obispo, CA 93407-0251, USA
Interests: dairy product structure and chemistry; partitioning and release of flavour volatiles from food matrices; flavour generation at colloidal interfaces; rheology; particle size analysis; emulsion science Contribution: Special Issue: Structure and Flavour of Dairy Products

Special Issue Information

Dear Colleagues,

The structure of dairy products, such as cheese, yogurt, butter, milk powders, and ice cream, is a complex arrangement of proteins, fat, water, and minerals that dictates the texture of the product. Different methods can be employed to modify structure and texture, which may then influence the creation (generation) and the release of flavor volatiles. This in turn influences the sensory perception of texture and flavor by consumers. Fat reduction of dairy products to create a healthier product will have an important impact upon structure and flavor, however this often reduces the consumer acceptability of a product. This special issue will feature reports on how dairy product structure dictates flavor, the sensory properties of dairy products when changes are made to structure, novel methods to change texture and flavor, and new and current methods of analysis to assess structure and flavor compounds.

Dr. David W. Everett
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Foods is an international peer-reviewed Open Access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 300 CHF (Swiss Francs). English correction and/or formatting fees of 250 CHF (Swiss Francs) will be charged in certain cases for those articles accepted for publication that require extensive additional formatting and/or English corrections.

Keywords

  • structure
  • flavor
  • dairy
  • milk
  • texture
  • sensory
  • volatile
  • consumer
  • analytical methods

Published Papers (7 papers)

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Research

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Open AccessArticle Change in Color and Volatile Composition of Skim Milk Processed with Pulsed Electric Field and Microfiltration Treatments or Heat Pasteurization
Foods 2014, 3(2), 250-268; doi:10.3390/foods3020250
Received: 9 December 2013 / Revised: 28 March 2014 / Accepted: 10 April 2014 / Published: 23 April 2014
Cited by 3 | PDF Full-text (372 KB) | HTML Full-text | XML Full-text
Abstract
Non-thermal processing methods, such as pulsed electric field (PEF) and tangential-flow microfiltration (TFMF), are emerging processing technologies that can minimize the deleterious effects of high temperature short time (HTST) pasteurization on quality attributes of skim milk. The present study investigates the impact [...] Read more.
Non-thermal processing methods, such as pulsed electric field (PEF) and tangential-flow microfiltration (TFMF), are emerging processing technologies that can minimize the deleterious effects of high temperature short time (HTST) pasteurization on quality attributes of skim milk. The present study investigates the impact of PEF and TFMF, alone or in combination, on color and volatile compounds in skim milk. PEF was applied at 28 or 40 kV/cm for 1122 to 2805 µs, while microfiltration (MF) was conducted using membranes with three pore sizes (lab-scale 0.65 and 1.2 µm TFMF, and pilot-scale 1.4 µm MF). HTST control treatments were applied at 75 or 95 °C for 20 and 45 s, respectively. Noticeable color changes were observed with the 0.65 µm TFMF treatment. No significant color changes were observed in PEF-treated, 1.2 µm TFMF-treated, HTST-treated, and 1.4 µm MF-treated skim milk (p ≥ 0.05) but the total color difference indicated better color retention with non-thermal preservation. The latter did not affect raw skim milk volatiles significantly after single or combined processing (p ≥ 0.05), but HTST caused considerable changes in their composition, including ketones, free fatty acids, hydrocarbons, and sulfur compounds (p < 0.05). The findings indicate that for the particular thermal and non-thermal treatments selected for this study, better retention of skim milk color and flavor components were obtained for the non-thermal treatments. Full article
(This article belongs to the Special Issue Structure and Flavour of Dairy Products)
Open AccessArticle Comparative Evaluation of Diagnostic Tools for Oxidative Deterioration of Polyunsaturated Fatty Acid-Enriched Infant Formulas during Storage
Foods 2014, 3(1), 30-65; doi:10.3390/foods3010030
Received: 31 October 2013 / Revised: 9 December 2013 / Accepted: 17 December 2013 / Published: 27 December 2013
Cited by 3 | PDF Full-text (1101 KB) | HTML Full-text | XML Full-text
Abstract
The challenge in the development of infant formulas enriched with polyunsaturated fatty acids (PUFAs) is to meet the consumers’ expectations with regard to high nutritional and sensory value. In particular, PUFAs may be prone to fatty acid oxidation that can generate potential [...] Read more.
The challenge in the development of infant formulas enriched with polyunsaturated fatty acids (PUFAs) is to meet the consumers’ expectations with regard to high nutritional and sensory value. In particular, PUFAs may be prone to fatty acid oxidation that can generate potential rancid, metallic and/or fishy off-flavors. Although such off-flavors pose no health risk, they can nevertheless lead to rejection of products by consumers. Thus, monitoring autoxidation at its early stages is of great importance and finding a suitable analytical tool to perform these evaluations is therefore of high interest in quality monitoring. Two formulations of infant formulas were varied systematically in their mineral composition and their presence of antioxidants to produce 18 model formulas. All models were aged under controlled conditions and their oxidative deterioration was monitored. A quantitative study was performed on seven characteristic odor-active secondary oxidation products in the formulations via two-dimensional high resolution gas chromatography-mass spectrometry/olfactometry (2D-HRGC-MS/O). The sensitivity of the multi-dimensional GC-MS/O analysis was supported by two additional analytical tools for monitoring autoxidation, namely the analysis of lipid hydroperoxides and conjugated dienes. Furthermore, an aroma profile analysis (APA) was performed to reveal the presence and intensities of typical odor qualities generated in the course of fatty acid oxidation. The photometrical analyses of lipid hydroperoxides and conjugated dienes were found to be too insensitive for early indication of the development of sensory defects. By comparison, the 2D-HRGC-MS/O was capable of monitoring peroxidation of PUFAs at low ppb-level in its early stages. Thereby, it was possible to screen oxidative variances on the basis of such volatile markers already within eight weeks after production of the products, which is an earlier indication of oxidative deterioration than achievable via conventional methods. In detail, oxidative variances between the formulations revealed that lipid oxidation was low when copper was administered in an encapsulated form and when antioxidants (vitamin E, ascorbyl palmitate) were present. Full article
(This article belongs to the Special Issue Structure and Flavour of Dairy Products)
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Open AccessArticle Dairy-Based Emulsions: Viscosity Affects Fat Difference Thresholds and Sweetness Perception
Foods 2013, 2(4), 521-533; doi:10.3390/foods2040521
Received: 1 August 2013 / Revised: 12 November 2013 / Accepted: 22 November 2013 / Published: 27 November 2013
Cited by 3 | PDF Full-text (529 KB) | HTML Full-text | XML Full-text
Abstract
In complex emulsions, viscosity or viscosity-associated sensory attributes such as creaminess are important for quality assessment and product differentiation. Two sets of emulsions with fat or locust bean gum content being varied at seven levels were developed; the two emulsions at each [...] Read more.
In complex emulsions, viscosity or viscosity-associated sensory attributes such as creaminess are important for quality assessment and product differentiation. Two sets of emulsions with fat or locust bean gum content being varied at seven levels were developed; the two emulsions at each level had similar apparent viscosity. Additionally, sugar concentration was kept constant either with respect to total emulsion, or with respect to the aqueous phase. Series of two-alternative forced choice tests were performed with one constant stimulus, and just noticeable differences were calculated using probability regression. The results show that, when viscosity was not compensated, it was easy for the subjects to (a) distinguish emulsions with different fat content when the fat content was addressed in the question, and to (b) distinguish emulsions with different fat or locust bean gum content when creaminess was addressed. For the latter descriptor, it is of minor importance whether viscosity is altered by fat content or a thickener. Weber fractions that were calculated for viscosity were approximately 0.20. The quantitative effects of viscosity on sweetness, however, depend on how product rheology was modified. Full article
(This article belongs to the Special Issue Structure and Flavour of Dairy Products)
Open AccessArticle Comparison of SPME Methods for Determining Volatile Compounds in Milk, Cheese, and Whey Powder
Foods 2013, 2(4), 534-543; doi:10.3390/foods2040534
Received: 24 September 2013 / Revised: 21 November 2013 / Accepted: 25 November 2013 / Published: 27 November 2013
Cited by 4 | PDF Full-text (259 KB) | HTML Full-text | XML Full-text
Abstract
Solid phase microextraction and gas chromatography-mass spectrometry (SPME-GC-MS) are commonly used for qualitative and quantitative analysis of volatile compounds in various dairy products, but conditions have to be adjusted to maximize release while not generating new compounds that are absent in the [...] Read more.
Solid phase microextraction and gas chromatography-mass spectrometry (SPME-GC-MS) are commonly used for qualitative and quantitative analysis of volatile compounds in various dairy products, but conditions have to be adjusted to maximize release while not generating new compounds that are absent in the original sample. Queso Fresco, a fresh non-melting cheese, may be heated at 60 °C for 30 min; in contrast, compounds are produced in milk when exposed to light and elevated temperatures, so milk samples are heated as little as possible. Products such as dehydrated whey protein are more stable and can be exposed to longer periods (60 min) of warming at lower temperature (40 °C) without decomposition, allowing for capture and analysis of many minor components. The techniques for determining the volatiles in dairy products by SPME and GC-MS have to be optimized to produce reliable results with minimal modifications and analysis times. Full article
(This article belongs to the Special Issue Structure and Flavour of Dairy Products)
Open AccessArticle Behavior of Heat-Denatured Whey: Buttermilk Protein Aggregates during the Yogurt-Making Process and Their Influence on Set-Type Yogurt Properties
Foods 2013, 2(4), 444-459; doi:10.3390/foods2040444
Received: 16 July 2013 / Revised: 18 September 2013 / Accepted: 22 September 2013 / Published: 30 September 2013
Cited by 1 | PDF Full-text (1330 KB) | HTML Full-text | XML Full-text
Abstract
The objective of this study was to assess the impact of using heat-denatured whey:buttermilk protein aggregate in acid-set type yogurt production. Whey and buttermilk (25:75) protein concentrate was adjusted to pH 4.6, heated at 90 °C for 5 min, homogenized and freeze-dried. [...] Read more.
The objective of this study was to assess the impact of using heat-denatured whey:buttermilk protein aggregate in acid-set type yogurt production. Whey and buttermilk (25:75) protein concentrate was adjusted to pH 4.6, heated at 90 °C for 5 min, homogenized and freeze-dried. Set-type yogurts were prepared from skim milk standardized to 15% (w/v) total solids and 4.2% (w/v) protein using different levels of powdered skim milk or freeze-dried protein aggregate. The use of the protein aggregate significantly modified yogurt texture, but did not affect the water-holding capacity of the gel. Confocal laser-scanning microscope images showed the presence of large particles in milk enriched with protein aggregate, which directly affected the homogeneity of the clusters within the protein matrix. Thiol groups were freed during heating of the protein aggregate suspended in water, suggesting that the aggregates could interact with milk proteins during heating. Full article
(This article belongs to the Special Issue Structure and Flavour of Dairy Products)
Open AccessArticle Microstructure and Composition of Full Fat Cheddar Cheese Made with Ultrafiltered Milk Retentate
Foods 2013, 2(3), 310-331; doi:10.3390/foods2030310
Received: 29 May 2013 / Revised: 18 June 2013 / Accepted: 9 July 2013 / Published: 18 July 2013
Cited by 5 | PDF Full-text (3237 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Milk protein is often standardised prior to cheese-making using low concentration factor ultrafiltration retentate (LCUFR) but the effect of LCUFR addition on the microstructure of full fat gel, curd and Cheddar cheese is not known. In this work, Cheddar cheeses were made [...] Read more.
Milk protein is often standardised prior to cheese-making using low concentration factor ultrafiltration retentate (LCUFR) but the effect of LCUFR addition on the microstructure of full fat gel, curd and Cheddar cheese is not known. In this work, Cheddar cheeses were made from cheese-milk with or without LCUFR addition using a protein concentration of 3.7%–5.8% w/w. The fat lost to sweet whey was higher in cheese made from cheese-milk without LCUFR or from cheese-milk with 5.8% w/w protein. At 5.8% w/w protein concentration, the porosity of the gel increased significantly and the fat globules within the gel and curd tended to pool together, which possibly contributed to the higher fat loss in the sweet whey. The microstructure of cheese from cheese-milk with a higher protein concentration was more compact, consistent with the increased hardness, although the cohesiveness was lower. These results highlight the potential use of LCUFR for the standardization of protein concentration in cheese-milk to 4%–5% w/w (equivalent to a casein to total protein ratio of 77%–79% w/w) to increase yield. Beyond this concentration, significant changes in the gel microstructure, cheese texture and fat loss were observed. Full article
(This article belongs to the Special Issue Structure and Flavour of Dairy Products)
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Review

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Open AccessReview Conventional and Innovative Processing of Milk for Yogurt Manufacture; Development of Texture and Flavor: A Review
Foods 2014, 3(1), 176-193; doi:10.3390/foods3010176
Received: 5 November 2013 / Revised: 6 February 2014 / Accepted: 25 February 2014 / Published: 11 March 2014
Cited by 8 | PDF Full-text (315 KB) | HTML Full-text | XML Full-text
Abstract
Milk and yogurt are important elements of the human diet, due to their high nutritional value and their appealing sensory properties. During milk processing (homogenization, pasteurization) and further yogurt manufacture (fermentation) physicochemical changes occur that affect the flavor and texture of these [...] Read more.
Milk and yogurt are important elements of the human diet, due to their high nutritional value and their appealing sensory properties. During milk processing (homogenization, pasteurization) and further yogurt manufacture (fermentation) physicochemical changes occur that affect the flavor and texture of these products while the development of standardized processes contributes to the development of desirable textural and flavor characteristics. The processes that take place during milk processing and yogurt manufacture with conventional industrial methods, as well as with innovative methods currently proposed (ultra-high pressure, ultrasound, microfluidization, pulsed electric fields), and their effect on the texture and flavor of the final conventional or probiotic/prebiotic products will be presented in this review. Full article
(This article belongs to the Special Issue Structure and Flavour of Dairy Products)

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