Fermentation Process: Making Cassava Tape Fermentation

If observed after 24 hours of fermentation, the tape is white, has a slightly sweet and slightly sour taste with a pH of 4, and has a distinctive sharp tape aroma and a slightly soft texture. Tape fermented for 48 hours has a creamy colour, slightly sweet and slightly sour taste with a pH of 5, the characteristic aroma of tape is more prominent than 24 hours tape, and the texture is softer. Meanwhile, the fermentation time of 72 hours gives the tape a creamy color, sweet and slightly sour taste with a pH of 5, a characteristic sharp tape aroma, and a soft texture.

Observation results show that the length of cassava fermentation affects various parameters of final product quality, including color, taste, aroma, texture and pH. This is probably because the longer the fermentation time will increase the enzymatic activity of microorganisms which will degrade natural cassava root components, changing them and causing changes in the sensory and physicochemical properties of the tape. For example, increased microbial fermentation results in the production of organic acids that lower the pH and the production of new volatile compounds that change the aroma. Texture changes can also be caused by enzymatic degradation of tape and structural components.  In particular, long fermentation times will affect the alcohol content of the tape, because fermenting microorganisms such as yeast produce ethanol through sugar metabolism. The average ethanol content of cassava tape was 0.844% after 24 hours of fermentation, 2.182% after 48 hours of fermentation, and 4.904% after 72 hours of fermentation. The more than two fold increase in ethanol from 24 to 48 h and a further increase after 72 hours indicate that alcohol production continued over the long fermentation times. 

The accumulation of ethanol on the tape had a significant influence on the fermentation time, and the alcohol content gradually increased from 1 to 7 days of fermentation. However, after 7 days, the ethanol content decreased. This phenomenon can be linked to the population dynamics of Saccharomyces cerevisiae, the main alcohol-producing microbial yeast. If fermentation continues for more than 7 days, this yeast enters a quiescent phase and its growth rate decreases due to lack of nutrients and accumulation of waste products. Therefore, S. cerevisiae is reduced, fermentation capacity and ethanol synthesis are reduced. 

In contrast to ethanol, the research results showed that there was no real influence of yeast concentration and fermentation time on cassava tape glucose levels. This lack of change may be explained by the high initial concentration of fermentable cassava starch, a substrate that is converted to glucose by amylase. With this abundant substrate, metabolic processes may take even longer beyond the time points tested. Apart from chemical components such as acids and alcohol, microbial activity during fermentation also has a significant influence on the physical properties of tape products. This includes noticeable effects on texture. For example, for purple sweet potatoes, the longer the fermentation time, the softer the texture of the tape. After 72 hours, the tape becomes completely soft and has a smooth texture. In contrast, a short fermentation of 24 to 48 hours produces a firmer, chunkier texture. 

The biochemical basis of the texture change of fermented tape is the breakdown of complex starch molecules into simpler dextrin and sugars in a process known as enzymatic hydrolysis. Sources of amylase and other enzymes that degrade polysaccharides include fungi, yeast, and bacteria that form mixed starter cultures. By breaking down macrostructure determining components such as starch, the entire matrix is softened by extensive enzymatic action. 

In addition to the preservative effect, the digestibility of the starch produced by this fermentation also contributes to the attractive sensory properties, easy digestion, and higher nutritional value of the final product. The increase in taste and aroma of ribbons can be caused by microbial synthesis of new volatile compounds and increased release of aromatic compounds from the fermented substrate. Additionally, the partially degraded contents of the tape are more easily accessible to consumers' digestive enzymes, thereby increasing digestibility. From a nutritional perspective, monosaccharides and dextrin formed through fermentation hydrolysis are more easily absorbed than original starch. 

Biochemical analysis showed that the fermentation time was correlated with an increase in the acidity of the tape product, which was indicated by a decrease in the pH value. This is related to the production of various volatile fatty acids by microorganisms during fermentation. These include lactic acid from lactic acid bacteria, as well as acetic acid, formic acid, butyric acid, and propionic acid. This acid is produced by the metabolism of carbohydrates and alcohol in cassava. Increased sour taste was noted in sensory analysis of longer fermented tape. It also lowers the pH, because the increase in hydrogen ion concentration is accompanied by an increase in acidity. 

Previous research is consistent with the trend of increasing alcohol content observed with prolonged steaming and fermentation. Although the measured increase was not statistically significant, it suggests a positive relationship facilitated by the longer reaction time of microbial enzymatic processes. During the fermentation period, there are more opportunities for catabolic transformation cascades to occur, which increase the content of final products such as ethanol. These include the direct synthesis of alcohol by yeast and the formation of ethanol from intermediate compounds such as acetaldehyde. 

The choice of culture temperature influences the specific microorganisms that can grow and ferment. For tape, the optimal temperature range for microbial activity is 35C to 40C. If the value is too low then microbial growth will be slow, and if the value is too high there will be negative impacts such as protein denaturation. Acidity, which is regulated by acid accumulation, also influences fermentation microorganisms, with the optimal pH for growth being between 3.5 and 5.5. Since oxygen availability depends on the air tolerance of microorganisms, their activity requires primarily anaerobic conditions, so the space required for movement and contact with air is limited. Finally, the specific strains of yeast, bacteria, and fungi included in the starter inoculum have specific enzymatic capabilities that shape the pattern of acidification, structural damage, and chemical changes that underlie the final characteristics of the tape. 

By adjusting these interdependent parameters, the fermentation progress and quality characteristics of the resulting tape product can be adjusted. For example, if the starter contains too much yeast, microbial activity will become uncontrolled and the tape will become too soft. Overall, this framework of complex interactions between processing methods, environmental factors, and microbial growth highlights the balance required to achieve desired sensory and nutritional properties in fermented foods such as tape. Subtle changes can produce very different tapes, when the tape is fermented for 24, 48, and 72 hours. 

The production of tape is considered traditional biotechnology as it uses limited conventional methods. When producing tape, yeast consumes the glucose contained in cassava as food for growth. This softens the cassava and allows the mushrooms to convert glucose into alcohol. During fermentation, the yeast Saccharomyces cerevisiae produces enzymes that break down carbohydrates in cassava into simple sugars. This means that ripe tape is sweet without the need for added sugar. Fermentation time on influence the alcohol content, pH, and sensory properties of cassava tape, such as taste, aroma, and texture. This indicates that fermentation time influences physicochemical and sensory properties. On the other hand, yeast concentration affects moisture more than sugar content.