Components of Yoghurt Quality Control - Term Paper Example

Components of Yoghurt Quality Control Abstract Yoghurt is made from naturally found bacteria and raw milk. This is a widely used substance and is consumed for its nutritional as well as taste and texture values. Understanding how yoghurt is manufactured leads to questions on the components of quality control. To explore quality control of yoghurt, this study will examine case study research and prepare results based on the common relationships of previous research and the yoghurt manufacturing process. This allows the research to use a descriptive analysis and form the resulting conclusions that explore the important concepts in the quality control of yoghurt. Many diseases and disorders prevalent in Europe today can be linked to poor food quality. Food quality control is the improvement, validation and harmonisation of reliable and cost-effective sampling and measurement strategies. Food contaminated with pathogenic microorganisms or other agents capable of causing illness, food insecurity can result. Food quality control experts aim to improve the quality of food so that it is fit for the purpose it was intended. Food safety may be defined as all preventative measures taken during production, processing, storage, distribution and preparation of food to ensure that the food does not represent any appreciable health risk. The object is to recognise and remove chemical contaminants and microorganisms with the goal to control the safety of the food and feed supply and ensure accurate data for risk analysis. Production and processing technology, as well as distribution systems, rigorously control pathogens and contaminants, yet new food safety concerns may occur outside of the control of the manufacturer. Foodstuffs often come from more than one source, and are often combinations of raw materials from different production systems. Yoghurt may come from the dairy, but also includes foods from orchards and farms, and is then transported to the store and purchased by the end customer. Yoghurt has been used for many centuries, and in different forms throughout the world. Yoghurt is a unique milk product because of the symbiotic fermentation involved in its manufacturing. In Turkey, day-old yoghurt is used as a starter culture for the production of yoghurt. Globally, yoghurt made at home is fairly close to manufactured yoghurt. These variances remove full quality control from the dairy manufacturer, and therefore require an examination of quality control techniques. To make yoghurt, the milk is heated to approximately 87 °C. This kills unwanted organisms and bacteria found in milk (Fuller 1994). The milk is then cooled to 46° to 48°C (Fuller 1994), which prevents the mesophilic lactobacilli from dying and encourages the growth of Streptococcus thermophilus, a thermophile that rapidly ferments lactose (milk sugar) to lactic acid (Cichoke 1998). Lactose is a disaccharide (2 covalently linked sugars) composed of glucose and galactose which are connected by a glucosidic bond (Cichoke 1998). Lactose is transported into the cell and the glucosidic bond is broken by the enzyme beta-galactosidase (Cichoke 1998). After the lactose is broken into galactose and glucose, both sugars are converted to glucose-6-phosphate (Cichoke 1998). Then, S. thermophilus oxidizes glucose-6-phosphate to lactic acid using the Embden-Meyerhoff-Parnas (EMP) pathway (Cichoke 1998). Active yoghurt culture is inoculated into the cooled milk (Fuller 1994). The bacteria present in commercial yogurt with "active cultures" are Streptococcus thermophilus and Lactobacillus bulgaricus. Streptococcus thermophilus is called a homolactic acid bacterium, as are all of the streptococci that ferment sugars (Cichoke 1998). Homolactic acid bacteria ferment sugars using and carbon atoms in glucose end up in the excreted lactic acid molecules (Cichoke 1998). This excreted acid increases the hydrogen-ion concentration thus lowering the pH. Milk directly from the cow has a pH of 6.6, and the milk protein casein is suspended until the streptococci excrete lactic acide and react with calcium casenite to form calcium lactated and soluble casein (Cichoke 1998). As the pH level lowers to 4.6, casein will coagulate and form a semisolid curd (Fuller 1994). The temperature is then cooled and the growth of thermophile slows, and Lactobacillus bulgaricus begins to ferment the lactose in the milk (Fuller 1994). Lactobacilli are more acid resistant than other lactic acid bacteria and are important in the final stages of lactic acid fermentation (Cichoke 1998). Lactobacillus bulgaricus also carries out a homolactic fermentation using the EMP pathway to ferment lactose to lactic acid (Cichoke 1998), but will use other minor pathways to produce volatile organic compounds that give yogurt its characteristic flavor and aroma (Fuller 1994). This continues until the temperature falls below the point of active metabolism of the lactobacilli. The finished yoghurt product does not need to be refrigerated because the acid prevents growth of other bacteria (Fuller 1994). Historical Methodology To find information regarding the compontents of quality control in yoghurt, secondary research data will be collected. This allows for an evaluation of results to be made on the empirical views and new information to be gathered in a timely and inexpensive manner based on information that is already in existence, and followed by creating a hierarchy of important characteristics of yoghurt. The most common information sources of it are interviews, questionnaires, and observations etc. compared with quantitative approach, qualitative approach is more flexible but seems incapable in analyzing research data. Qualitative data will be collected due to some components of the study not having material outputs. Collection of information will be by multiple sources to include documents and previous journal research. This will allow the research to develop beyond core statistics into recorded responses. This method is particularly important, as qualitative information will allow for an opportunity the survey method does not; it will allow the researcher to respond to the comments, studies and suggestions through the investigation. Qualitative document study will include case study analysis, because the case study is a helpful way of establishing valid and reliable evidence for the research process as well as presenting findings result from the research (Kasanen and Suomi 1987). In the case study, documentation on the quality control of yoghurt will be analyzed. The result will come from an analysis of all-available experiences, processes and recommendations. Case study research is very common as a qualitative method. The scope is to develop an empirical inquiry that investigates the content and context of yoghurt. Yin (1993) has identified some specific types of case studies: Exploratory, Explanatory, and Descriptive. This will be a descriptive case study analysis. The case study allows for a multi-perspective analysis, where multiple sources of data are examined to come to a conclusive meaning in relationship to the accounting methods. While the case study analysis has sometimes been considered a generalisation, Yin (1993) describes this method as a template to develop empirical results, but asserts that there is a caution towards generalisation. This means that not evidence from a case study can be lumped into one category because of various factors, such as organisational behavior and management strategy that would affect the outcome of the case study. Yin (1993) further identifies sources of evidence for data collection in the case study protocol: documentation, archival records, interviews, direct observation, participant observation, and physical artifacts. For this research, the primary focus is on documentation within the case study analysis. Analysis Quality Control of Yoghurt Esteve (et. al. 2002) found that diacetyl permits the detection of microbial growth in the processing of citrus fruit before the appearance of other organoleptic, chemical or microbiological changes. It also makes it possible to detect a break in the cold chain during distribution and sale (Esteve et al 2002). The study proposed a polarographic method for the determination of diacetyl that allowed routine analysis with the aim of detecting possible contamination in the citrus juice manufacturing chain (Esteve et al 2002). The same method was also applied to butter and yoghurt with detection limits of and 0.4 ng g[sup -1] (Esteve et al 2002). Yoghurts from cow's milk containing 2 kg milk fat/100 kg or 2 kg of an oat-maltodextrin/100 kg (maltodextrin included 5 kg b-glucan/100 kg), were weighed on a laboratory scale and stored in refrigerator conditions for 21 days (Domagal et al 2005). Non-fat yoghurt without the addition of maltodextrin was used as a control product (Domagal et al 2005). The yoghurts were analysed after 1, 7, 14, and 21 days of storage (Domagal et al 2005). Sensory evaluation, instrumental texture profile analysis, and rheological investigations were carried out (Domagal et al 2005). They included the determination of the flow curves and the description by Ostwald de Waele and Casson models as well as an account of the apparent viscosity (Domagal et al 2005). Differences in the sensory quality of yoghurts containing milk fat or maltodextrin were not found, whereas these yoghurts were characterized by better sensory quality than the control product (Domagal et al 2005). The storage time had a significant influence on the sensory evaluation and the texture parameters. During the storage time, the apparent viscosity of yoghurts decreased (Domagal et al 2005). A decrease in consistency index value, in deviation from Newtonian flow, and yield stress was noticed, whereas in Casson's viscosity of the yoghurts, an increase was found (Domagal et al 2005). Cheddar whey obtained from milk from either a Jersey (J) or a mixed (M) herd was used to observe the effect of whey source (WSr) and whey processing (WPr) on dairy product quality (Haque and Ji 2003). These were (i) ultrafiltered, vacuum-evaporated and spray-dried after lactose crystallization (UFVECSD) and (ii) vacuum-evaporated and spray-dried after lactose crystallization (VECSD) (Haque and Ji 2003). These were used to replace non-fat dry milk (NDM) in vanilla-flavoured non-fat yoghurt and non-fat ice cream at 20, 60, 80 and 90% (w/w solids) (Haque and Ji 2003). Physicochemical and sensory properties of products were assessed on days 1, 15 and 30. In yoghurt, regardless of WSr, pH and titrable acidity were similar in treatments compared to control (Haque and Ji 2003). All whey protein concentrates (WPCs) decreased apparent viscosity and syneresis (Haque and Ji 2003). Conversely, penetration increased with increased WPC usage(Haque and Ji 2003). All, except 20% VECSD, detrimentally affected texture. Syneresis was improved by both WSr and WPr but was better improved by WPr; UFVECSD was the best with regard to syneresis reduction (Haque and Ji 2003). Yoghurt flavour appeared WSr dependent with J-WPCs improving it most (Haque and Ji 2003). On the contrary, texture appeared WPr dependent with all VECSDs markedly improving this parameter. Both UFVECSDs at 60% usage level improved melting resistance (Haque and Ji 2003). Body and texture were improved by all VECSDs showing significant influence of WPr. Data indicated that both WSr and WPr impacted different attributes of dairy product quality (Haque and Ji 2003). Fruit flavors are found to slightly impact the pH levels of yoghurt. Fruit-flavoured yoghurt was made by adding 2.5, 5.0, 7.5 and 10.0% mulberry pekmez (MP) into milk (Celike and Bakirci 2003). The effects of the MP on the quality and fermentation process of the yoghurt were determined (Celike and Bakirci 2003). The titratable acidity, pH, viscosity, whey separation and lactic acid bacteria (LAB) counts were determined at weekly intervals for 28 days (Celike and Bakirci 2003). The pH range of the MP yoghurts was 4.65–5.57 and the pH of the plain yoghurt was 4.47 ( P < 0.05) (Celike and Bakirci 2003). The addition of MP led to an increase in the fermentation time and a decrease in the viscosity of the yoghurts (Celike and Bakirci 2003). Statistically significant differences were found between the plain and MP yoghurts in terms of pH (4.01 and 4.35), viscosity (5429 and 3175 cP) and number of LAB (7.07 and 6.48 log cfu) (Celike and Bakirci 2003). During storage, the titratable acidity, viscosity and LAB counts of MP yoghurts were lower and the whey separations higher than those of controls (Celike and Bakirci 2003). Fruit additives also impact the pH levels and subsequently the quality of yoghurt. The dwarf golden apple ( Spondias cytherea Sonn) is an exotic fruit which is mainly consumed in its fresh form but could be processed (Bartoo and Badrie 2005). One study investigated the effects of adding golden apple nectar on the physicochemical and sensory quality of stirred yoghurts from cow's milk (Bartoo and Badrie 2005). Yoghurts with 15% and 20% golden apple nectar were more ( P >0.01) liked than the control (0% nectar) yoghurt in all sensory attributes (Bartoo and Badrie 2005). The appearance and body attribute differed ( P 0.05) changes, in pH, lactic acid, consistency, colour, lactic acid bacteria and yeasts and moulds on storage at 4°C for 4 weeks (Bartoo and Badrie 2005). By week 4 of storage, yoghurts developed a buttery smell and were less dark and yellow (Bartoo and Badrie 2005). A 226g yoghurt serving provided an excellent source of phosphorus and was good in protein (Bartoo and Badrie 2005). Results The resulting data analysis finds the following organisational chart to show the main characteristics of yoghurt quality control: Quality Control of Yoghurt I. Chemical Changes Chemical changes are noted in nearly all previous studies, where the reactions create the taste and texture of the yoghurt. Detection limits are identified as the point at which yoghurt is viable as a food stuff, or subsequently becomes inedible. This is another important concept in quality control of yoghurt manufacturing. pH levels and titratable acidity are the points at which milk becomes yoghurt, note previously that the pH of milk is around 6.6, where the pH levels of yoghurt are around 4.5. The pH level of yoghurt is also related to the time-sensitivity of yoghurt manufacturing, where the majority of studies revealed a specific amount of time to record and analyse the chemical changes and properties of yoghurt. Additives such as fruit, diacetyl, maltodextrin and whey also impact the quality of yoghurt, as noted in the previous studies. The quality and chemical properties such as acidity change with the additives. II. Microbial Growth Bacteria are single celled organisms that can only be seen with the aid of a microscope and are neither plant nor animal. Only select groups are of concern to the dairy industry. Thermoduric bacteria are a miscellaneous group of bacteria that are capable of surviving pasteurization or other heat treatments. Thermodurics in milk are found in poorly cleaned equipment and may contaminate. Microbial growth was noted to have a serious impact on quality control in all studies. The foundation of yoghurt development is the growth of bacteria, and the amount of bacteria per mL establishes the contamination level of the yoghurt, where too much bacteria shows bad or poor yoghurt quality, and too little bacteria will not manufacture tasty and texture appropriate yoghurt. III. Physicochemical The most important components of quality control in yoghurt can be identified as having physicochemical properties. This is the commutation of the chemical and microbial changes as well as the sensory evaluation of yoghurt, such as texture and viscosity. The cummulation of the above components develops the texture and viscosity of quality yoghurt. Conclusion In conclusion, the manufacturing process of yoghurt is nearly the same in home and factory development of the dairy product. Yoghurt is essentially made from milk inoculated with specific bacterium to form the chemical changes, especially in the lactose and glucose as well as the structure of carbons within the yoghurt. Controlling the temperature under time-sensitive conditions is used to manufacture yoghurt and increase its shelf-life. This is only one component necessary to develop adequate yoghurt, other properties of quality control include monitoring and developing the chemical changes that occur. This includes additives such as fruits and whey to change the flavour and texture of yoghurt. A quality end product is made from the control of the microbial, chemical and physicochemical properties as it is manufactured, as well as finding new ways to enhance the flavour, texture and viscosity of yoghurt. Understanding the components of the quality control of yoghurt will help in future research to determine better methodologies and decrease risk of contamination. Future research should look towards preventing contamination by unhealthy bacteria, as well as improving the ‘good’ bacteria used in yoghurt with the implications towards the nutritional value. This includes finding better additives and decreasing risk of negative chemical reactions from such substances. . References Bartoo, Shelly Ann; Badrie, Neela. (2005) Physicochemical, Nutritional And Sensory Quality Of Stirred ‘Dwarf’ Golden Apple ( Spondias Cytherea Sonn) Yoghurts. International Journal of Food Sciences & Nutrition, Sep2005, Vol. 56 Issue 6, p445-454, 10p Celik, Serafettin; Bakirci, Ihsan (2003) Some Properties Of Yoghurt Produced By Adding Mulberry Pekmez (Concentrated Juice). International Journal of Dairy Technology, Feb2003, Vol. 56 Issue 1, p26-29, 4p Cichoke Anthony J The Complete Book of Enzyme Therapy Publisher: Avery; 1 edition (November 15, 1998) Domagala, Jacek; Sady, Marek; Grega, Tadeusz; Bonczar, Genowefa (2005) The Influence of Storage Time on Rheological Properties and Texture of Yoghurts with the Addition of Oat-Maltodextrin as the Fat Substitute. International Journal of Food Properties, Jul2005, Vol. 8 Issue 2, p395-404, 10p, 4 charts, 2 graphs Esteve, M. J.; Frígola, A.; Rodrigo, M. C.; Rodrigo, M.. (2002) Use Of Polarography As A Quality-Control Method For Determining Diacetyl In Citrus And Vegetable Juices, Yoghurt And Butter. Food Additives & Contaminants, Jun2002, Vol. 19 Issue 6, p519-523, 5p Fuller, Linda K. (1994) Yogurt, Yogourt, Youghourt. Publisher: Food Products Press. Haque, Z. U.; Ji, T (2003) Cheddar Whey Processing And Source: II. Effect On Non-Fat Ice Cream And Yoghurt[Sup 1]. International Journal of Food Science & Technology, Apr2003, Vol. 38 Issue 4, p463, 11p Kasanen, Eero - Suomi, Reima (1987) The Case Method In Information Systems Research. Vammala. Vol. 36 No. 4, 323-338. Yin, Robert (1993) Case Study Research : Design and Methods (Applied Social Research Methods) Sage Publications, Inc; 2nd edition Read More