žMaking yogurt

žLactic Acid Fermentation      

žIntroduction

žYogurt production demonstrates fermentation by Streptococcus thermophilus and Lactobaacillus bulgaricus

žHeated milk is inoculated and maintained at a given temperature causing bacteria to grow and ferment lactose, the suger in milk

žThe bacteria produce lactic acid which causes the milk to coagulate

žMateriales

žFood grade containers, washed

žFood grade thermometer

žHotplate

žBeaker tongs

ž2 cup of milk

ž1/3 cup nonfat dry milk

ž2 table spoons yogurt

žpH meter

žProcedure

žCombine milk with nonfat dry milk and heat in water bath to 87ºC

žHold at that temperature for 10 to 20 minutes

žCool to 46ºC and record the pH of the mixture

žPlace the plain yogurt in jar and gradually blend in the warm milk

žCover and place in oven or incubator at  45ºC

žAllow to stand undisturbed until the mixture is firm when the jar is gently wiggled

žThis may take as long as 6 to 8 houres

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ÖZET  

Bu  çalışmanın  esası  yoğurt  üretiminde  HACCP  organizasyonuna  dayanmıştır.  Bu   çalışmada günlük 80-100 ton süt işleme kapasitesine sahip bir tesisin yoğurt üretim hattında   HACCP sistemi kurulmuştur. Çalışmada   metot   olarak   7   temel   HACCP   prensibinden   baz   alınarak   geliştirilen mantıksal HACCP  organizasyon  şeması  kullanılmıştır  (Ünlütürk  ve  Turantaş,1998;  Karaali,   2003; Anonymous, 2005).  Şirketin HACCP Planının geliştirilmesinde Kanada Gıda Denetim   Kurumunun jenerik HACCP modellerinden yararlanılmıştır.         Çalışmada  ilk  olarak  söz  konusu  planı  gerçekleştirebilecek  bilgi  ve  uzmanlığa  sahip   üçü  fabrikanın  farklı  kademelerinde  görev  yapan  beş  kişilik  bir  ekip  oluşturulmuştur.  Ekip   tarafından ürünün tanımı yapılmış ve sürece etkileyen önemli ürün özellikleri (pH, minimum   yağ  ve  yağsız  kuru  madde  yüzdeleri  vb.)  belirlenmiş,  ürün  ingredientleri  ve  hammaddeleri   listelendikten sonra bir proses akış şeması hazırlanmıştır. Ürünün   hammaddesinden   son   ürüne   kadar   tüm   aşamalarda   ortaya   çıkabilecek   tehlikeler bilimsel kaynaklardan araştırılmış ve oluşturulan HACCP  ekibi ile   değerlendirilmiştir. Hammaddeden (çiğ süt) başlayarak ürünün dağıtımına kadar ortaya konan   her bir potansiyel tehlike kritik kontrol noktası karar ağacına tatbik edilmiştir. Çalışmamızda   6  farklı  kritik  kontrol  noktası  tespit  edilmiş  olup,  söz  konusu  işlem  aşamaları  şu  şekilde   sınıflandırılmıştır:  1)  Hammadde  (Çiğ  süt  ve  süt  tozu);  2)  Çiğ  süt  soğutma  ve  depolama; 3)  Pastorizasyon;  4)  Starter  kültür  alımı  ve  ilavesi;  5)  Kaselere  dolum;  6)  İnkübasyon  /   Soğutma HACCP  çalışmasının  güvenirliğini  artırmak  için  kritik  kontrol  noktalarının  asgaride   tutulmasına  dikkat  edilmiştir.  Kritik  kontrol  noktaları  dışında  kalan  kontrol  noktalarının   güvenliği      alım     spesifikasyonları,        standart     operasyon   prosedürleri, GMP (İyi    Üretim   Uygulamaları) ve GHP (İyi Hijyen Uygulamaları) benzeri ön şart programları ile sağlanmıştır. 2007, 67 sayfa

Anahtar kelimeler: Gıda güvenliği, HACCP, Yoğurt

SUMMARY  

The  foundation  of  this  study  is  based  on  the  HACCP  organization  in  yoghurt   production. In this study, HACCP system was set up in the yoghurt production line of a dairy   plant which has a daily capacity of 80 – 100 tonnes of milk. The logic sequence for application of HACCP which had been developed basing on 7   basic principles (Unlütürk and Turantas,1998; Karaali, 2003; Anonymous, 2005) was used as   a method in this study. In the development of the company’s HACCP plan, generic HACCP   models of Canadian Food Inspection Agency (CFIA) were been utilized. Initially  a  team  consisting  of  five  persons  three  of  whom  are  employed  in  different   positions of the company and who had sufficient knowledge and expertise to be able to carry   out the plan in question were assembled. The definition of the product was made by the team,   and important product characteristics those effect on the process (pH, minimum fat and SNF   percentages etc.) were determined and after  the product ingredients and raw materials have   been listed a process flow diagram was prepared. The hazards that could arise from the raw  material of the product to the end product   were researched and they were been evaluated by the assembled HACCP team. Each potential   hazard  that  have  been  put  forward  from  raw  material  (raw  milk)  to  the  distribution  of  the   product was been applied to the critical control point decision tree. 6 different critical control   points  was  determined  and  the  process  stages  in  question  were  been  classified  as  follows: 1)   Raw   material   (Raw   milk   &   Milk   powder);   2)   Raw   milk   cooling   and   storage; 3) Pastorization; 4) Purchase  and addition of starter cultures; 5) Packaging; 6) Incubation /   Cooling                In order to enhance the reliability of the HACCP study, it was paid attention to keep   the critical control points at the minimum level. The safety of the control points other than the   critical   control   points   were   assured   by   the   prerequisite   programs   such   as   purchase   spesifications, standard operation procedures, GMP (Good Manufacturing Practices) and GHP   (Good Hygiene Practices). 2007, 67 pages

Keywords: Food safety, HACCP, yoghurt

Fermentation of yoghurt is the most important part of the production.For fermentation process ,streptecoccus thermophilus and lactobacillus bulgaricus are added at 1:1 ratio as starter culture.There are also other bacterias in the product such as mold and yeast ,lactic acid bacteria etc. Detection of these microorganisms has an important role for safety of products. In this experiment we have used two kinds of yoghurt sample prepared in aceptic conditions and in open environment.We have examined the differences in the number of microorganisms in these samples.We have used different agars fort hat purpose.That is because,total lactic acid bacteria can be determined with MRS agar ,s.thermophilus and lactobacillus bulgaricus can be differentiated by using lee’s agar. Because , s.thermophilus ferment sucrose and produce yellow color but l.bulgaricus can’t so that we can differentiate them from each other by using lee’s agar.In M-17 agar, reproduction of s.thermophilus bacterias is observed.In PCA agar, at 30 °C microorganisms other than lactic acid bacterias can be detected.Also during sample preparation, we diluted our sample with a different way because that our sample was solid so we took 25 gr and dissolved it in 225 ml of sterile water to obtain a well mix.In the results,the number of microorganisms in open yoghurt are greater than the number in pasteurized yoghurt. That is because,in pasteurized yoghurt,the yoghurt product is pasteurized during the production so the number of microorganisms is reduced because of heat threatment and aceptic packaging.But in open yoghurt,it is produced in open environment so the product is exposed to air and other factors such as human interferences and non aceptic packaging.However,we have also observed that the results are a bit strange and unacceptable.Because when yoghurt samples are diluted and inoculated ,the obtained number of microorganisms are greater in so diluted samples such as 10-5 such as 10-2 because of wrong calculations or careless experiment work etc. or 10-6 than less diluted samples or 10-3 .This is not an expected case.This mistakes may be

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