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Research Question How does fermentation time fermented papaya Carica papaya Introduction 0 2 4 6 and 8 days affect the lactic acid concentration of Most food substances range from 2 6 on the pH scale showing that most naturally have either low or high acidity McGlynn 2016 One of the benefits of this is that pathogenic bacteria do not tend to grow on highly acidic foods Microorganisms tend to propagate in pH levels 6 6 7 5 Iowa State University n d Even if a particular fruit or vegetable is only slightly acidic the organic acid level can be further lowered by means of the fermentation process Fermentation is the metabolic process in which molecules of glucose are broken down anaerobically There are two types of fermentation alcohol and lactic acid fermentation The similarity between the two fermentation processes is the passing of electrons from NADH to a specific molecule producing a specific by product lactic acid and ethanol Alcohol fermentation is a two step process that involves the production of acetaldehyde As a carboxyl group is removed from a pyruvate molecule Khan Academy n d electrons in NADH are passed onto acetaldehyde regenerating NAD and forming ethanol On the other hand lactic acid fermentation is a process wherein NADH transfers its electrons to pyruvate the product of glycolysis via oxidation and generates lactic acid as a by product Khan Academy n d C O 3H3 3 pyruvate NADH C3H6 O 3 lactic acid NAD Due to the carboxyl group present in lactic acid it can decrease the pH of a substance It was discovered due to the lack of oxygen the process of fermentation produced lactic acid catalyzed from the hydrolysis of glucose particles heterofermentative lactobacilli bacteria also produces carbon dioxide The low pH present in food is due to the high amounts of hydrogen ions present McGlynn 2016 A popular pickled food is pickled cucumbers and it is said to contain anti hypertensive properties Avant 2019 Pickling is the process of adding an acid to preserve food products vinegar is typically used in this process In salt brining lactic acid produced by fermentation does the preservation action Monta o et al 2016 In the Philippines a fruit that is commonly pickled C papaya Pickled foods can be stored in cool dry places but is papaya fermented food should be stored in temperatures ranging from 20 to 4 C Cabello Olmo et al 2020 Both processes preserve food products so that it can be eaten days after it is made by decreasing the pH thereby increasing the organic acid level of the food and adding a sour flavor In this study I will be monitoring the lactic acid content of papaya C papaya at different fermentation days Research Question How does fermentation time affect the lactic acid concentration of fermented papaya Carica papaya Background of the Study Picking of Fruits and Vegetables Pickling fruits and vegetables is a common culinary practice throughout the world Asia boasts various pickled and fermented food such as the all famous kimchi p oc i tur u and atchara The latter is a famous Filipino relish made with raw green papaya C papaya as well as other add ons such as bell peppers and raisins The main ingredient papaya C papaya is an exotic fruit that is native to Central America However it is also grown in abundance in the Philippines Its health benefits include an improvement of blood glucose control within diabetic people digestion and lowering blood pressure It is also used in numerous local dishes such as tinola and ukoy An increase in free galacturonic acids during ripening is typically associated with the increase in the total acidity of papaya Hewajulige et al 2016 has a pH level of around 6 0 in 50 color yellow fruit and 5 2 The tissue of papaya in 100 color yellow fruit As unripe papaya will be used the pH level is 6 0 Hewajulige et al 2016 C papaya C papaya C papaya C papaya The process of pickling papaya is to shred then brine it in salt to prevent putrefaction Steinkraus 1992 thus the fermentation process begins A syrup made with edible vinegar and spices is then added to the brined papaya and vegetables This particular syrup gives the atchara a mild level of acidity as white vinegar vinegar commonly used in atchara has a pH of around 2 5 Whelan 2019 The initial brining of the vegetables extracts excess liquid acting as a good substrate for the growth of fermentative lactobacilli Since papaya C papaya is a low acid fruit it has an initial total titratable acidity of around 0 1 this is calculated as citric acid Moy 2003 The fermentation time takes about 2 days before one can enjoy the acidity that soaks into the vegetables however some choose to let it stay in the refrigerator more C papaya around days up 10 or to Factors Affecting Lactic Acid Content of Food During Fermentation One factor that affects the acidity of food is temperature lactic acid content decreases in lower temperatures as a study gathered that after 8 weeks the lactic acid content of kimchi filtrate at 4 C was 5 194 9 mg kg and 12 621 2 mg kg at 10 C You et al 2017 Another factor would be an anaerobic environment A study detailing the fermentation process of sauerkraut shows that leuconostoc mesenteroides which aid in the production of lactic acid and carbon dioxide in the cabbage provides an anaerobic environment for fermentation Steinkraus 1992 In terms of fermentation time a study conducted experimented on pickled ginger Zingiber officinale Rosc and tested for the effects of salt concentration and fermentation time on the total acidity level expressed in lactic acid content Susilowati et al 2017 Looking at the data sets with 25 salt concentration the greater the fermentation time the higher the lactic acid content Another study measured the lactic acid concentration of kimchi filtrate to be 188 1 mg kg after 2 weeks and 5195 9 mg kg after 8 weeks You et al 2017 As there is a conversion of the fermentable present in the vegetables into lactic acid This is further evidenced by the fact that around 85 90 of fermentable sugar coming from the different vegetables in atchara is converted into lactic acid as fermentation time increases Siegrist n d Methods of Measuring Lactic Acid Z officinale Rosc There are different methods to measure the relative lactic of atchara or any pickled vegetable or fruit Firstly one could either manually count the lactic acid bacteria colonies or measure the concentration of a basic solution such as NaOH then convert it to lactic acid A study obtained fermented ginger

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HARVARD CHEM 10 - Final Chemistry IA Draft

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