Papers by Johannes Hogenboom
Journal of Dairy Science, 2016
Chemical composition and structure of different types of macroparticles (specks, spots) and micro... more Chemical composition and structure of different types of macroparticles (specks, spots) and microparticles (microcrystals) present in hard and extra-hard cheeses were investigated. Light microscopy revealed that the small hard specks had the structure of crystalline tyrosine, as confirmed by amino acid analysis. Spots showed a complex structure, including several curd granules, cavities, and microcrystals, and were delimited by a dense protein layer. Spots contained less moisture and ash than the adjacent cheese area, and more protein, including significantly higher contents of valine, methionine, isoleucine, leucine, tyrosine, and phenylalanine. Microcrystals were observed by light and electron microscopy and analyzed by confocal micro-Raman. Among others, calcium phosphate crystals appeared to consist of a central star-shaped structure immersed in a matrix of free fatty acids plus leucine and phenylalanine in free form or in small peptides. A hypothetical mechanism for the formation of these structures has been formulated. Key words: hard and extra hard cheeses, cheese ultrastructure, calcium phosphate crystal, free amino acids, electron microscopy
Molecules
Increasing awareness of balanced diet benefits is boosting the demand for high-protein food and b... more Increasing awareness of balanced diet benefits is boosting the demand for high-protein food and beverages. Sports supplements are often preferred over traditional protein sources to meet the appropriate dietary intake since they are widely available on the market as stable ready-to-eat products. However, the protein components may vary depending on both sources and processing conditions. The protein fraction of five commercial sports supplements was characterized and compared with that of typical industrial ingredients, i.e., whey protein concentrates and isolates and whey powder. The capillary electrophoresis profiles and the amino acid patterns indicated that, in some cases, the protein was extensively glycosylated and the supplemented amino acids did not correspond to those declared on the label by manufacturers. The evaluation by confocal laser scanning microscopy evidenced the presence of large aggregates mainly enforced by covalent crosslinks. The obtained findings suggest tha...
Food Research International, 2018
Consiglio per la ricerca in Agricoltura e l'analisi dell'economia agraria, CREA-ZA Via A.
Food Microbiology, 2016
Lysozyme (LZ) is used in several cheese varieties to prevent late blowing which results from ferm... more Lysozyme (LZ) is used in several cheese varieties to prevent late blowing which results from fermentation of lactate by Clostridium tyrobutyricum. Side effects of LZ on lactic acid bacteria population and free amino acid pattern were studied in 16 raw-milk hard cheeses produced in eight parallel cheese makings conducted at four different dairies using the same milk with (LZ+) or without (LZ-) addition of LZ. The LZ-cheeses were characterized by higher numbers of cultivable microbial population and lower amount of DNA arising from lysed bacterial cells with respect to LZ+ cheeses. At both 9 and 16 months of ripening, L. delbrueckii and L. fermentum proved to be the species mostly affected by LZ. The total content of free amino acids indicated the proteolysis extent to be characteristic of the dairy, regardless to the presence of LZ. In contrast, the relative patterns showed the microbial degradation of arginine to be promoted in LZ+ cheeses. The data demonstrated that the arginine-deiminase pathway was only partially adopted since citrulline represented the main product and only trace levels of ornithine were found. Differences in arginine degradation were considered for starter and non-starter lactic acid bacteria, at different cheese ripening stages.
Journal of Dairy Science, 2019
Automatic milking systems (AMS), first introduced on dairy farms in the 1990s, rapidly spread acr... more Automatic milking systems (AMS), first introduced on dairy farms in the 1990s, rapidly spread across many countries. This technology is based on the voluntary milking of dairy cattle in a completely automated process, which relies on computer management, with a substantial average increase in milking frequency. Compared with conventional milking, AMS significantly alters herd management, with important implications on economic, technical, and social aspects of farming, on animal physiology, health, and well-being. These aspects are explored in an extensive body of research. In contrast, the effects of AMS adoption on milk quality are often overlooked. This review draws together both positive and negative effects of AMS on the milk production chain, particularly emphasizing the variations of hygienic and compositive characteristics of raw milk and their interplay, as compared with milk obtained with conventional milking. Scattered and sometimes conflicting literature exists on whether and how these variations may influence quality and yield of the derived dairy products. Current scientific knowledge on these crucial aspects is thus reviewed, with particular focus on milk technological suitability for being processed into dairy products having the target characteristics in terms of taste, structure, on-storage stability, and sustainability. Provided the managing conditions are optimized, AMS allow increased milk production, mostly due to more frequent milking, without compromising the milk characteristics that are crucial to food industry for processing. Nevertheless, specific biochemical aspects related to the changed milking interval, which determines the duration of enzyme activities and bacterial growth in milk, need further research.
Advanced Dairy Chemistry, 2012
ABSTRACT The first part of this chapter outlines general aspects concerning dietary proteins, i.e... more ABSTRACT The first part of this chapter outlines general aspects concerning dietary proteins, i.e. protein requirements in human diet, role and nutritional quality of proteins and methods for its evaluation (CS, Protein Digestibility Corrected AA Score [PDCAAS]), protein digestibility and efficiency of protein utilisation. The second part specifically focusses on the amino acid composition and nutritional properties of milk proteins, the peptides and amino acids deriving from their digestion (protein turnover, regulation of gastrointestinal function and antibody production, cell signalling) and the effects of milk processing on these properties. This chapter concludes with an overview of functional foods obtained from specific milk proteins.
– The sensorial and physico-chemical characteristics described in the product specifica-tion for ... more – The sensorial and physico-chemical characteristics described in the product specifica-tion for most PDO cheeses are inadequate to verify the compliance of cheeses on the market with the registered designation, particularly for grated products. During the past few years, much research has indicated the analytical parameters suitable for distinguishing Grana Padano (GP) from other similar hard cheeses. The characterization of grated GP is currently based on 3 analytical param-eters, related to different aspects of cheese processing, which are: (i) the measurement of alkaline phosphatase (ALP) activity, a marker for possible heat treatment applied to milk, in the outermost layer of the cheese, just below the rind; (ii) the identification of specific peptides, that are iden-tified only in the rind, due to the very slow progress of proteolysis in the rind during GP cheese ripening; and (iii) the free amino acid (FAA) composition. In the present study, we developed an extraction method,...
Foods, Mar 2, 2020
Extending ripening of hard cheeses well beyond the traditional ripening period is becoming increa... more Extending ripening of hard cheeses well beyond the traditional ripening period is becoming increasingly popular, although little is known about the actual evolution of their characteristics. The present work aimed at investigating selected traits of Parmigiano Reggiano cheese ripened for 12, 18, 24, 30, 40 and 50 months. Two cheeses per each ripening period were sampled. Although moisture constantly decreased and was close to 25% in 50-month cheeses, with a parallel increase in cheese hardness, several biochemical changes occurred involving the activity of both native and microbial enzymes. Capillary electrophoresis demonstrated degradation of αs1- and β-casein, indicating residual activity of both chymosin and plasmin. Similarly, continuous release of free amino acids supported the activity of peptidases deriving from lysed bacterial cells. Volatile flavor compounds, such as short-chain fatty acids and some derived ketones, alcohols and esters, evaluated by gas chromatography with solid-phase micro-extraction, accumulated as well. Cheese microstructure was characterized by free fat trapped in irregularly shaped areas within a protein network, with native fat globules being no longer visible. This study showed for the first time that numerous biochemical and structural variations still occur in a hard cheese at up to 50 months of aging, proving that the ripening extension deserves to be highlighted to the consumer and may justify a premium price.
Biomolecules
Cheese Whey Permeate (CWP) is the by-product of whey ultrafiltration for protein recovery. It is ... more Cheese Whey Permeate (CWP) is the by-product of whey ultrafiltration for protein recovery. It is highly perishable with substantial disposal costs and has serious environmental impact. The aim of the present study was to develop a novel and cheap CWP-based culture medium for Lactobacillus sakei to produce the food-grade sakacin A, a bacteriocin exhibiting a specific antilisterial activity. Growth conditions, nutrient supplementation and bacteriocin yield were optimized through an experimental design in which the standard medium de Man, Rogosa and Sharpe (MRS) was taken as benchmark. The most convenient formulation was liquid CWP supplemented with meat extract (4 g/L) and yeast extract (8 g/L). Although, arginine (0.5 g/L) among free amino acids was depleted in all conditions, its supplementation did not increase process yield. The results demonstrate the feasibility of producing sakacin A from CWP. Cost of the novel medium was 1.53 €/L and that of obtaining sakacin A 5.67 €/106 AU, ...
Foods
The implementation of quality assurance schemes for the assessment of PDO food authenticity is an... more The implementation of quality assurance schemes for the assessment of PDO food authenticity is an issue involving manufacturers, traders, retailers and consumers. In this respect, reliable analytical methods are needed to integrate paper-trailing information. The feasibility of distinguishing the Italian Fontina PDO cheese from the generic Fontal cheese was preliminarily evaluated on a set of commercial samples by measuring selected parameters (pH, alkaline phosphatase activity, content of copper, volatiles, extent of proteolysis) related to the different manufacturing processes. The relative profile of free amino acids proved to be a promising tool. A new set of 41 samples of Fontina PDO cheese was collected at representative dairies within the recognized production area and analyzed for free amino acids. A chemometric model of Fontina PDO cheese was built based on the mean content and standard deviation of 15 free amino acids. On this basis, all of the PDO samples were correctly i...
Journal of Dairy Research
With the aim to reduce the Na content, hard cheeses manufactured using the same technology as for... more With the aim to reduce the Na content, hard cheeses manufactured using the same technology as for Grana cheese (Grana-type) were salted using three brines containing different amounts of KCl (K-brines) and compared with control cheeses, salted with marine NaCl. A lower weight loss was observed in cheeses salted with K-brines (K-cheeses), whereas the yield and dry matter did not differ significantly between K-cheeses and controls. After 3 months of ripening (T3), the distribution of the Na cations (Na) was centripetal, with a higher Na concentration in the outer (0–3 cm of depth) layer, whereas the K cations (K) seemed to diffuse into the cheese more rapidly and homogeneously. Starting from the 6th month (T6), the distribution of both Na and K was stabilized through the different cheese layers. The use of the brine with the highest concentration of potassium (53.8% K) enabled us to successfully halve the Na content compared to the controls whereas, with the other brines, the reductio...
Food Analytical Methods
Although free amino acids (FAAs) represent a significant component of ripened cheeses and can pro... more Although free amino acids (FAAs) represent a significant component of ripened cheeses and can provide useful information for their characterization, no inter-laboratory validated analytical method exists which allows a reliable comparison of data obtained by different laboratories and the adoption of quality control schemes based on FAA pattern. The objective of the present work was to test the effectiveness of an analytical protocol for the determination of the FAA composition of cheese and to verify the adequateness of this type of analysis for quality control procedures of Grana Padano PDO cheese as well as for research purposes. After an initial test to compare performances of ion-exchange chromatography (IEC) and HPLC techniques, an inter-laboratory collaborative study (seven laboratories, four samples) was organized to validate an IEC method with post-column ninhydrin derivatization and using L-norleucine as an internal standard. Determined amounts of individual FAA ranged from 8 to over 1380 mg/100 g cheese, with relative standard deviation of repeatability (RSD r) ranging from 0.5 to 4.6%, and relative standard deviation of reproducibility (RSD R) ranging from 1.3 to 9.9% for FAA concentrations over 100 mg/100 g. For lower concentrations, RSD r and RSD R were about thrice as high. On the basis of the results of this investigation, at present, the validated method is adopted as the official method for the determination of FAA patterns in the quality control of Grana Padano PDO cheese.
LWT - Food Science and Technology
The late blowing defect still represents a problem for hard cheeses. Thus, the behaviour of the c... more The late blowing defect still represents a problem for hard cheeses. Thus, the behaviour of the cheese spoiling bacterium C. tyrobutyricum was studied throughout the cheesemaking and ripening of Grana Padano using an innovative approach. Cells and spores, independently sealed within dialysis tubes, were kept in the vat during the entire cheesemaking and then into cheese until 6-2 month ripening. At each sampling step, morphological changes of cells and spores were monitored by electron microscopy and supported with plate counts. Vegetative cells died during curd cooking and then were no longer cultivable. However, 2 x 10 2 spores appeared at the end of this stage, likely triggered by the exponential growth phase, and were present until 6-month ripening. In cheese, C. tyrobutyricum UC7086 proved to convert free arginine to citrulline and then to ornithine, and to produce γ-aminobutyric acid by glutamate transamination rather than by decarboxylation. Compartmentalization of vegetative cells and spores into dialysis tubes was effective in studying their respective behaviour in a real cheesemaking. This approach allowed to demonstrate that the number of vegetative cells in milk in addition to that of spores should be considered for the eradication of the late blowing defect.
Journal of food science, Jan 29, 2017
Molecular properties of proteins and starch were investigated in 2 accessions of Oryza glaberrima... more Molecular properties of proteins and starch were investigated in 2 accessions of Oryza glaberrima and Oryza sativa, and in one NERICA cross between the 2 species, to assess traits that could be relevant to transformation into specific foods. Protein nature and organization in O. glaberrima were different from those in O. sativa and in NERICA. Despite the similar cysteine content in all samples, thiol accessibility in O. glaberrima proteins was higher than in NERICA or in O. sativa. Inter-protein disulphide bonds were important for the formation of protein aggregates in O. glaberrima, whereas non-covalent protein-protein interactions were relevant in NERICA and O. sativa. DSC and NMR studies indicated only minor differences in the structure of starch in these species, as also made evident by their microstructural features. Nevertheless, starch gelatinization in O. glaberrima was very different from what was observed in O. sativa and NERICA. The content of soluble species in gelatiniz...
International Dairy Journal, May 1, 2010
Different chemical indices related to proteolysis and ripening time have been investigated in Gra... more Different chemical indices related to proteolysis and ripening time have been investigated in Grana Padano (n ¼ 155) and Parmigiano-Reggiano (n ¼ 27) cheese samples using ion-exchange chromatography and capillary electrophoresis. Levels of intact caseins, g-casein and free amino acids in cheese were not strictly related to the maturation period, varying among samples of the same age. A peptide, identified by HPLC/electrospray ionization-mass spectrometry as pyroglutamyl-g 3-casein, resulted from cyclisation of N-terminal glutamic acid into a pyroglutamic acid residue. Based on the peak area ratio of pyroglutamyl-g 3-casein and g 3-casein, an equation, suitable for determination of the cheese age, is proposed. The commercial classes of Grana Padano ripened over 16 and 20 months can be identified by adopting a minimum threshold value for this peak area ratio.
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Papers by Johannes Hogenboom