Sensory and Microbiological Properties of Pickled Bamboo Shoots (Bambusa vulgaris)

Most people currently preserve bamboo shoots (Bambusa vulgaris) that have been harvested using alum which has an adverse effect on the human body. Alternative preservation of bamboo shoots can be done by making bamboo shoots using a solution of sugar and salt solution. This study aims to determine the effect of salt and sugar concentrations on the sensory and microbiological properties of pickled bamboo shoots. The design used was the factorial method in the basis of a completely randomized designs (CRD) using two factors, namely salt solution and sugar solution. The formulation used were sugar concentration 1%; 2%; 3% and salt concentration 10%; 12.5%; 15% Sensory test results showed that the concentration of sugar and salt affected the hedonic test values of color, aroma, and texture. Whereas microbiological analysis showed that there is an increase in the total plate count by increasing fermentation time


Introduction
Bamboos are a unique group of giant arborescent grasses in which the woody culms arise from underground rhizomes [1]. Bamboo shoots (Bambusa vulgaris) have long been known by people as a food ingredient, especially for traditional cuisine, but the development of these food ingredients has not been so good. Bamboo shoots can be used as a single vegetable or can be mixed with other food ingredients [2]. Bamboo shoots have important benefits in society, such as in several Eastern Asian countries such as China, Taiwan, Korea and Japan, so that cultivation and processing technology has developed. At present bamboo shoots have become an international trade commodity and have been processed into canned food. Bamboo shoots contain carbohydrates that have the potential to be processed as fiber-rich bamboo shoots. Bamboo shoots that have been used are bamboo shoots that are around 1-5 months old because at that age shoots can be consumed which are thought to have the best age and for flour making. The shoots are usually harvested when they attain the height of 15-16 cm [3]. If the age is too young or too old, it will affect the yield of bamboo shoot flour.
Efforts to increase added value and to extend the shelf life of products, processing bamboo shoots into pickled can be used as an alternative in processing. Pickled is the result of processing fruit or vegetables using salt and preserved with acids, with or without the addition of sugar and spices as seasonings [4]. Pickling with salt is a familiar practice and it generatesmost shelf-stable and organoleptically sound foods [5]. Bamboo shoots has a harvest during the rainy season while in the dry season it cannot be harvested. Bamboo shoots are used as traditional food, such as in Semarang used as spring rolls. Most people preserve bamboo shoots that have been harvested using alum, which has adverse effects on the human body such as impaired liver and kidney function. In this research, pickling will be done by using a sugar solution and a salt solution. The purpose of this study was to determine the effect of salt and sugar concentrations on the sensory and microbiological characteristics of pickled bamboo shoots

Method
Bamboo shoot fermentation begins with the preparation of sugar and salt solution. The bamboo shoots are peeled and washed and then weighed as much as 1 kg for each treatment. The main treatment procedures for making bamboo shoots are as follows: fresh sorted bamboo that is not deformed, washed and peeled. After the shoots are peeled, the shoots are made into cubes with a size (1x1x1 cm). Then, prepare the fermentation container including washing and sterilizing glass jars for 15 minutes by boiling in boiling water for 15 minutes. Then the bamboo shoots are put into a sterilized glass jar, then mixed with a salt solution with a concentration of 10%, 12.5%, and 15% in each treatment into a sterile glass jar containing bamboo shoots and 1%, 2%, 3% sugar solution with a ratio of bamboo shoots 200 grams and 250 ml solution. Then fermented in a sterile glass jar, covered and fermented to become bamboo shoots and analyze until the 7 th and 14 th day.

Research Design
The study was conducted using a factorial design on the basis of a completely randomized design (CRD) using two factors, namely the concentration of salt solution and sugar solution. There are two control used in this research, namely control 1 (sugar 0%, salt 0%) (K1) and control 2 (alum 3%) (K2). Data were analyzed using Diversity Analysis (ANOVA). If there are differences, the Duncan's Multiple Range Test (DMRT) is continued with a 95% confidence level. Data analysis using SPSS version 21 computer software.  Table 2 showed the results of the highest color hedonic bamboo shoot test, namely 3.93 in bamboo shoots fermentation with 3% sugar solution and 10% salt solution. Panelists tended to prefer bamboo shoots with lower salt concentrations, this was due to the higher concentration of salt solution used in the color of bamboo shoots produced so the panelists less liked it. The change in color produced by the pickled bamboo shoots was influenced by the concentration of sugar and salt used, high salt concentrations will inhibit the fermentation process, causing the pickled color to turn yellow. Whereas the untreated bamboo shoots produced blackish brown color, this was due to the absence of treatment and cause spoilage of the bamboo shoots. Whereas the lowest hedonic shoot color test results were in control one which did not do any treatment, it happened because the shoots did not undergo fermentation, causing the bamboo shoots to store decay and brown color.   Table 3 it can be seen that the concentration of the sugar and salt solution used was significantly different from the hedonic test of pickled bamboo shoots produced. On the 14 th day pickled bamboo shoots experienced a more yellowish color change compared to the 7 th day. Panelists tend to prefer pickled bamboo shoots with lower concentrations of sugar and salt solutions, because adding a solution of sugar and salt that is too high will cause the surface of pickled bamboo shoots to turn yellow, whereas pickled bamboo shoots without treatment are not preferred by panelists because of their black surface. Organoleptic test results of pickled bamboo shoots from day 0 to day 14 for 30 panelists can be seen in Figure 1.

Fig. 1. Color hedonic test results of pickled bamboo shoots
Based on Figure 1, it can be seen that the hedonic test or preference test on pickled shoots on day 0 showed results that are not significantly different. Panelist response to the color of bamboo shoots produced decreases with increasing fermentation time.
Panelists prefer pickled bamboo shoots fermented with 3% sugar solution and 10% salt solution. This happens because the color change produced by pickled bamboo shoots is influenced by the concentration of sugar and salt used, high salt concentrations will inhibit the fermentation process, causing the color of the pickled to be more yellow. Discoloration occurs due to the addition of too much salt which can inhibit the growth of hetero fermentative lactic acid bacteria and cause normal fermentation to not take place [6]. The higher the concentration of salt solution, the optimum fermentation will occur which causes the color of pickled shoots to turn yellow.

Aroma Hedonic Test
The concentration of the sugar and salt solution used is not significantly different whereas the samples that were not treated were significantly different, some panelists tended to rather like the scent produced on pickled bamboo shoots while those on untreated bamboo shoots were not liked by panelists a foul aroma.  Based on Table 5 it can be seen that the concentration of the sugar and salt solution used is not significantly different at the panelist preference level. Referring to the response given, it can be seen that the panelists do not have a particular preference for treatment in each group. However, it can be concluded that panelists prefer pickled with the addition of sugar and salt solutions compared to pickled stored in alum solution. Pickled is made by fermenting the ingredients in a 10-15% salt solution, adding salt can be done in stages or all at once. Addition of salt as much as 10% has better organoleptic reception than 15% salt solution.

Fig. 2. Aroma hedonic test results of pickled bamboo shoots
Based on Figure 2, it can be seen that the hedonic test or preference test on pickled shoots on day 0 showed results that are not significantly different, panelists tend to like the smell of bamboo shoots on day 0 which has not been treated. The panelists' preference scale for the highest aroma of pickled bamboo shoots on the 7 th day was obtained on pickled bamboo shoots with high concentrations of sugar and salt solutions. Whereas on the 14 th day the panelists' favorite scale of aroma was obtained in pickled shoots with a concentration of 10% salt solution and 3% sugar solution. Some panelists thought they liked the aroma in some pickled bamboo shoots. The smell of pickled bamboo shoots that is produced is rather aromatic and slightly aromatic. The results of the panelists' assessment of the aroma of pickled bamboo shoots showed that the addition of salt affected the preference level of panelists on the aroma of pickled bamboo shoots produced. Lactic acid bacteria are known to produce various aroma component, bacteriocins and exopolysaccharides which contribute to the development of some characteristic properties such as taste, visual appearance, texture, shelf life and safety

Texture Hedonic Test
Based on Table 6 it can be seen that the concentration of the sugar and salt solution used was significantly different at the panelist preference level. The highest level of preference for texture was pickled bamboo shoots with 15% salt concentration and 2% sugar with the average hedonic panelist rating of pickled bamboo shoots ranging from 2.40-3.23, this can be occured because the high concentration of salt solution will cause more and more nutrients to be attracted from the shoot through a semi-selective membrane selectively to a more concentrated solution and will produce a soft bamboo shoot texture [7].  Based on Table 7 it can be seen that the concentration of the sugar and salt solution used was not significantly different at the panelist preference level, but significantly different from control 1 that was not treated. The average hedonic panelist's assessment of pickled bamboo shoots ranged from 2.23 to 3.00 (rather like to neutral). The highest level of preference in texture is pickled bamboo shoots with salt concentrations of 12.5% and 15%, the concentration of salt solution given affects the texture of pickled bamboo shoots. The concentration of salt and microorganisms that help in softening vegetable tissue affects the texture of a fermented vegetable product. The results of the hedonic texture test from day 0 to day 14 can be seen in Fig. 3.   Fig. 3. Texture hedonic test results of pickled bamboo shoots Based on Figure 3, it can be seen that the hedonic test or preference test on pickled bamboo shoot day 0 shows results that are not significantly different, the average hedonic panelist assessment of pickled bamboo texture ranges from neutral to like. On the 7 th day the highest preference scale was 3.23 in bamboo shoots with a concentration of 15% salt solution and 2% sugar which showed a neutral to like value. Whereas on the 14 th day the highest preferred scale was 3.00 on pickled shoots with a concentration of 12.5% salt solution and 1% sugar which showed a neutral value.

Microbiological Properties
The total plate count on pickled bamboo shoots on the seventh day had significantly different results, the highest total plate count results are in control one or shoots that are not treated with the addition of salt and sugar solution that is equal to 8.425 cfu/ml so that the shoot will experiencing decay and microbes will grow a lot, the cause of microbial contamination in food can be caused by the initial number of microbes in food affecting the number of further microbes that will increase the number of microbial contamination in the product. Lactic acid bacteria are the dominant microorganisms in ethnic fermented vegetables and bamboo shoot products [8]. While the lowest total yield of pickled plate count bamboo shoots with 15% salt solution immersion is 6.992 cfu/ml, the results showed the higher the salt concentration, the lower the microbes produced. Salt concentrations that are too high will reduce acid production. Salt concentration caused lactic acid bacteria to be less able to convert sugar and cause yeast growth.   Table 9 can be seen that the total plate count on pickled bamboo shoots on the seventh day has significantly different results, the highest total plate count results are in control one or shoot that is not treated with the addition of salt and sugar solution that is equal to 8.518cfu / ml, in the control one bamboo shoot has decayed because no preservation was done with a solution of salt and sugar. While the lowest total yield of pickled plate count shoots with 15% salt solution immersion and 1% sugar is 8,155cfu / ml. Based on Figure 4, it can be seen that the microbiological analysis of total plate count on pickled shoots on day 0 shows results that are not significantly different, on day 0 or shoots that have not been treated, resulting in lower microbes that is 5.75 x 105 cfu/g. On the 7 th day there was an increase in microbes in pickled shoots, due to fermentation by lactic acid bacteria. Salt with the resulting acid will inhibit unwanted microbes. At this stage lactic acid bacteria begin to play a role and will reach peak growth on the first day of fermentation. Changes in the amount of lactic acid produced each day are influenced by microbial activity that grows. Bacterial growth is generally characterized by four phases: an initial non-growth period called the adaptation phase (lag phase), followed by a period of rapid growth (logarithmic/exponential phase), then leveling off (static phase), and finally followed by a decline in population living cells (phase of death or decline).

Fig. 4. Microbiological test results of pickled bamboo shoots
Salt concentration and type of fermentation media used affect the level of lactic acid produced. The higher the sugar content in the fermentation media, the higher the lactic acid produced. The higher the salt concentration, the lower the levels of lactic acid produced. Salt functions to remove certain substrate, especially sugar which is needed for the growth of lactic acid bacteria. Salt can draw water and nutrients from vegetables that will complement the substrate for the growth of lactic acid bacteria. Salt along with the acid are produced by fermentation inhibits the growth of undesirable organisms and delays softening of the shoot tissue due to the action of enzymes by pectinolytic bacteria. Salt levels must be considered because too high salt levels will delay natural fermentation and allow the growth of yeast.
On the 14 th day, pickled bamboo fermentation increased. The increase number of microbes is due to microbes experiencing growth in the form of an increase in the number of cells. Microbes make the use of nutrients (carbohydrates) that have been broken down into simple sugar to carry out growth activities and cause microbial growth to increase. This is supported by the results of the analysis of total sugar levels which are increasingly decreasing fermentation. But the total increase in microbes does not occur continuously. The longer the fermentation, the total microbes experienced an insignificant increase as at the beginning of fermentation. This is due to microbial succession. Microbes that have long been growing will experience death and be replaced with new microbes. Death from microbes occurs because the nutrients in the medium are used up, and the energy reserves in the cell are depleted. Based on the average results of total microbes, microbial growth during the study, has not shown signs of entering the static phase, because there is still an increase in total microbes.

Conclusions
The hedonic test results of color, aroma, and texture showed that the panelists on average gave a neutral value to the sample by fermentation treatment. Whereas in the sample without treatment, the average panelist gave the lowest value. The results of microbiological analysis showed significant differences in results on the 7th day. The results of the total plate count showed that the sample without treatment contained 8,425 cfu/ml microbes, more than the fermented bamboo shoot sample.