fermented food science of sauerkraut.pptx

Sauerkraut is a traditional fermented food made from finely shredded cabbage. The process begins with selecting fresh, mature cabbage heads, which are then cleaned and trimmed to remove any damaged or dirty outer leaves. The cabbage is finely shredded and layered with salt in a fermentation vessel. The salt draws out water from the cabbage through osmosis, creating a brine that covers the cabbage shreds.

This environment is ideal for lactic acid bacteria, which naturally occur on the cabbage leaves. These bacteria ferment the sugars in the cabbage, producing lactic acid. This acidification process lowers the pH, creating an acidic environment that inhibits the growth of harmful bacteria and preserves the cabbage. The fermentation typically occurs in anaerobic conditions (without oxygen) and lasts 3 to 4 weeks1.

The result is sauerkraut, which has a distinctive sour flavour and a long shelf life. The lactic acid not only preserves the cabbage but also enhances its nutritional value by increasing the availability of certain vitamins and producing beneficial probiotics2. Sauerkraut is a staple in many Central and Eastern European cuisines and is valued for its health benefits and unique taste.

1. sauerkraut

2. INTRODUCTION The term " sauerkraut " translates to "sour cabbage" or "acidic cabbage. " Cabbage, the primary vegetable used in preparing sauerkraut, is an excellent source of ascorbic acid, vitamins, and minerals . It is highly valued for its use in salads and culinary applications. Production of sauerkraut is a simple process , in which only two ingredients cabbage and salt are necessary. The simplicity of the process is reflected by the U.S. Standards, which states that sauerkraut is the “ product of characteristic acid flavor, obtained by the full fermentation, chiefly lactic, of properly prepared and shredded cabbage in the presence of not less than 2 percent nor 2 more than 3 percent of salt.”After fermentation, sauerkraut should contain not less than 1.5% acid (expressed as lactic acid).

3. MANUFACTURE SELECTION OF RAW MATERIAL White cabbage is typically used because it has a mild, slightly sweet flavor and contains 5% or more fermentable sugars They should be fully mature and have few outer leaves. SHREDDING The outer layer and spoiled leaves are washed thoroughly and the core is drilled out. The leaves are then shredded along with the core and segregated according to the weight and then transferred to the tanks where they get ready for salting .

4. SALTING Salting is an important step in the process . It provides optimum condition for discouraging the non lactic acid bacteria to growth which prevent spoilage . Once the pH has been lowered by the production of organic acids, the combination of salt and acid significantly contributes to the long preservation properties of the finished product. Additionally, salt adds a desirable flavor and helps maintain a crisp texture by preventing the softening of the tissues. Typically, between 2% and 2.5% salt is added by weight , which is considered optimal. After mixing the salt with the shredded cabbage, water starts to diffuse from the interior of the plant tissue to the exterior medium through simple osmosis. The resulting brine also contains sugars and other dissolved nutrients that diffuse out with the water. This water phase ultimately serves as the primary site for most microbial activity.

5. MIXING The shredded and salted cabbage is thoroughly mixed to ensure an even distribution of the salt . This prevents any localized concentrations of salt, ensuring that there is neither too little nor too much in any part of the mixture . It is important to note that high salt levels can lead to spoilage just as easily as low salt levels. For instance, the "pink" defect occurs due to the growth of salt-tolerant yeasts, which are usually suppressed by lactic acid bacteria. However, the growth of these beneficial bacteria is inhibited at high salt levels . Traditionally , sauerkraut was fermented in wooden barrels, though now concrete vats lined with fiberglass or plastic are common, holding up to 50,000 kg. The cabbage is covered with a plastic tarp and weighed down with water or brine, which expels air, reduces contamination, and promotes brine formation to cover the cabbage .

6. FERMENTATION The lactic fermentation in sauerkraut occurs in a series of overlapping stages or sequences . The first stage of sauerkraut fermentation, called the initiation or heterolactic phase, involves the growth of Leuconostoc mesenteroides . This salt-tolerant bacteria grows quickly at low temperatures (15°C to 18°C) and ferments sugars to produce lactic and acetic acids, CO2, and ethanol. The acidic environment it creates inhibits non-lactic bacteria and favors other lactic acid bacteria. The CO2 production also helps create an anaerobic environment. However, as the acid concentration reaches 1.0%, L. mesenteroides is inhibited and becomes barely detectable within four to six days. In the next stage , called the primary or homolactic phase , the decline of Leuconostoc coincides with the rise of other lactic acid bacteria, mainly Lactobacillus plantarum and Lactobacillus brevis . These bacteria produce a lot of acid, increasing the acidity to about 1.4% to 1.6%. L. plantarum thrives in this acidic environment and dominates the fermentation. As acidity reaches 1.6% and pH drops below 4.0, only L. plantarum continues to grow. The fermentation process can take one to two months and is complete when acidity is around 1.7% and pH is 3.4 to 3.6.

7. PACKGING At last they are pasteurized and packed for commercial use . Non-pasteurized sauerkraut are also sold , in refrigerated glass jars or sealed plastic bags (polybags). These products have a long shelf-life when kept cold, especially if antimycotic agents like benzoate and sulfite salts are added sauerkraut

8. FLOW CHART FRESH CABBAGE DELEAF, CORE AND TRIM(1mm THICK) SHRED SALT ( 2-3% W/W) FILL INTO VATS COVER AND SEAL IT EXTRACT MOISTURE FROM SHREDDED CABBAGE BY OSMOSIS ; INHIBIT OSMOSIS MAINTAIN CRISP, TEXTURE, FLAVOUR TRADITIONAL OR MODERN METHOD OF CONCREATE

9. FERMENT ( LACTIC ACID BACTERIA ) Ph BELOW – 4 PASTEURIZED LEUCONOTOC MESENTEROIDS AND LACTOBACILLUS PLANTARUM 4 – 8 WEEKS ; 1.7 – 2.3 % TOTAL ACTIVITY

10. ANANYA BSc BIOTECHNOLOGY HONS. THE END