Occurrence of sensory defects in semi-hard ewe’s raw milk cheeses

Dairy Sci. & Technol. (2016) 96:53–65 DOI 10.1007/s13594-015-0237-2 O R I G I N A L PA P E R Occurrence of sensory defects in semi-hard ewe’s raw milk cheeses L. Zabaleta 1 & M. Albisu 1 & M. Ojeda 1 & P. F. Gil 1 & I. Etaio 1 & F. J. Perez-Elortondo 1 & M. de Renobales 1 & L. J. R. Barron 1 Received: 3 December 2014 / Revised: 14 May 2015 / Accepted: 18 May 2015 / Published online: 4 June 2015 # INRA and Springer-Verlag France 2015 Abstract Sensory quality is one of the most important attributes of cheeses, as consumers demand homogeneous and unaltered products. The presence of sensory defects in the final product causes financial losses and consequently has a great economic impact on cheese makers. Therefore, a study was conducted to find out main defects that affect sensory quality: eyes, paste, rind, flavour, texture and shape of commercial semi-hard ewe’s raw milk cheeses. The frequency of occurrence of relevant sensory defects in cheeses with different ripening times and those manufactured in different seasons was also investigated. Samples were collected along 5 years during the annual sensory quality control from different cheese makers. Although flavour is a major determinant of consumer acceptance, most common defects were those related to the internal appearance, especially cracks, which were more frequent in summer cheeses, and caverns, which were more frequent in spring and winter cheeses. White paste, soft texture and acid flavour defects were more frequent in cheeses with shortripening period. Medium- and long-ripened cheeses presented a higher percentage of an excess of rind halo with a darker paste colour, animal flavour and marks in the rind. Due to compositional milk changes throughout cheesemaking seasons, cheese makers should adapt their manufacturing practises to those changes and try to achieve uniform cheeses. The results found in this study may be useful for the quality improvement of semi-hard ewe’s raw milk cheeses. Keywords Sensory quality . Defect . Ewe’s raw milk cheese . Seasonality . Ripening * L. Zabaleta 1 Lactiker Research Group. Pharmacy and Food Science Department, Faculty of Pharmacy, University of the Basque Country, UPV/EHU, Paseo de la Universidad 7, 01006 Vitoria-Gasteiz, Spain 54 L. Zabaleta et al. 1 Introduction Around 60% of global sheep milk cheese is manufactured in Europe, mainly in Mediterranean countries such as Greece, Italy and Spain (FAO 2014). Spanish sheep milk cheese production increased by 28% between 2002 and 2012 (FAO 2014). Ewes are mainly milked for the manufacture of typical dairy products, in particular cheeses, which often have a regional or local connotation of origin and quality (Boyazoglu and Morand-Fehr 2001). Local cheese production is an important economic activity, especially in Mediterranean countries (Caridi et al. 2003). In some cases, these cheese varieties have a strong brand image that connects the product to characteristic sensory attributes, to a particular animal management conditions and to traditional cheesemaking methods. That plays a positive role in the choice of the product by consumers (Boyazoglu and Morand-Fehr 2001). Sensory quality is one of the most important attributes of a food product, determined by its flavour, texture and appearance. The relative importance of these three quality attributes is interrelated but unfortunately these relationships have not been studied in depth. Initial microbiological and physicochemical characteristics of raw milk, as well as technological treatments, affect the different phases of the production and hence the final quality of the product (Mahaut et al. 2003). Any change in any of these milk characteristics and/or an incorrect processing, particularly in raw milk cheeses, may result in a lack of some desirable organoleptic attributes or in the presence of an undesirable defect (Pirisi et al. 2007). The presence of defects in the final product causes financial losses and consequently has a great economic impact on the dairy industry (Engel et al. 2001). The most studied defect is late blowing, as it is one of the major causes of spoilage in semi-hard and hard cheeses. It is predominantly caused by the growth of Clostridium tyrobutyricum that produces both texture and flavour defects (Feligini et al. 2014; Garde et al. 2012; Le Bourhis et al. 2007). Amongst cheese flavour characteristics, bitterness and unclean flavour (animal) have been particularly studied because of the consequences of economic loss, as these defects limit consumer acceptance (Engel et al. 2001). Studies reported in the literature concerning defects were mainly conducted with non-commercial or experimental cow’s milk cheeses with induced defects at laboratory scale. Defects were studied separately and independently rather than investigating interactive effects that could arise amongst them. Ripening is a major factor in determining the quality of small ruminant dairy products (Boyazoglu and Morand-Fehr 2001). It influences development of sensory characteristics of cheeses due to its effect on the chemical composition such as moisture loss, enzymatic activities including degradation of residual lactose, the lipolysis of fat increasing the total amount of free fatty acids and the proteolysis of casein leading to the production of amino acids and flavour precursors (Virto et al. 2003). In the same way, seasonality is a major source of variation especially for farmhouse cheese makers that practise pasture feeding and seasonal milk production (Barron et al. 2001; Farruggia et al. 2014). In those cases, the effects of both changes in feed sources and farm practises are interactive and cannot be separated (Kindstedt 2005). As a result of those sources of variability, a change in the frequencies of occurrence of sensory defects or differences in cheese’s defect profile could be expected. The aim of this study was to describe the main sensory defects that appear in semihard sheep raw milk cheeses, as well as interactions or relationships that may arise Sensory defects in ewe’s milk cheeses 55 amongst them. The frequency of occurrence of relevant sensory defects in cheeses with different ripening times and those manufactured in different seasons was also investigated. 2 Materials and methods 2.1 Sample collection Samples were collected during the annual sensory quality control of a semi-hard sheep’s raw milk cheese variety over five consecutive years (2006–2010). Commercial cheeses were manufactured in 126 different dairies in a similar manner. Milk was acidified by starter cultures and coagulated by the addition of rennet (commercial or traditional lamb rennet paste) at 25–35 °C. The resulting curd was cut into rice-sized grains and heated to 35–37 °C. Then, the curd was introduced into cylindrical 1–2 kg moulds, pressed and salted with saturated sodium chloride brine at 10–12 °C for 16–24 h. Cheeses were ripened at 8–10 °C for at least 2 months. Cheese samples with at (...truncated)