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Analysis of bamboo shoots packed using cluster level processing technology
Analysis of samples of bamboo shoots packed using NMBA cluster level processing technologies was carried out by Midlands Fruit and Vegetable Products (India) Private Limited, Delhi.
Cluster level Shoot Processing technology – The processing technology for shoots is an innovative break through for backward linkage before processing such as canning. Using this process, the shoots can be processed hygienically to stay close to fresh for 10 days. In this process, the raw shoots are cut, soaked in water to remove the bitter components and then drained the next morning. After draining, the cut shoots are packed in nylon based packages and then potable water is added to keep the cuts soaked in water. After sealing, the packs are labeled for date of packing and price of the packs. The processing cost is low, the process is hygienic and the product is suitable to be ideal to be sold to:
- Processors for further processing e.g. canning and freezing
- To meet the demand of institutional market
- For meeting local consumption and meeting self requirements
The samples were prepared and tested by varying the following parameters:
- Packaging material (two packaging materials – Nylon 90 microns and Poly Propylene 40 microns
- Presence or absence of water in the pack
- Temperature of storage (the products were kept at three temperatures – 5, 37 and 55 degree Centigrade)
The fresh bamboo shoot was also tested.
The tests carried out were:
Microbiological tests (M) Total Viable Count
Salmonella
Shigella
E. coli
Coliforms
Chemical tests( C) Brix
Acidity (%)
Salt
pH
Hydrocyanic Acid (%)
Benzoic Acid Percentage (%)
Organoleptic tests (O) Texture
Appearance
Taste
The schedule of the testing was (due to limited availability of the samples, the schedule had to be modified slightly):
Sample details |
Testing Days |
Temperature of storage |
Tests to be carried out |
Bamboo shoot + water packed in Nylon based pouches |
D4, D7, D10, D12, D14 |
37 °C |
M+C+O |
D7, D21 |
5 °C |
M+C+O |
D5 |
55 °C |
M+C+O |
Bamboo shoot + water packed in Poly Propylene based pouches |
D10 |
5 °C |
C+O (Microbiological analysis not done) |
D10 |
37 °C |
M+C+O |
D10 |
55 °C |
M+C+O |
Bamboo shoot without water in Nylon based pouches |
D10 |
37 °C |
M+C+O |
D10 |
55 °C |
M+C+O |
Bamboo Shoot, without water in PP pouches |
D10 |
37 °C |
M+C+O |
D10 |
55 °C |
M+C+O |
Fresh shoot (805 g) |
D 0 |
- |
M+C+O |
Fresh shoot (1205 g) |
D 0 |
- |
M+C+O |
* M = Microbiological Analysis, C = Chemical Analysis, O = Organoleptic Analysis
Additionally, the water sample was also tested microbiologically. Observations on the testing are placed below:
Fresh shoots
- The two samples of shoots of the specie Dendrocalamus asper were tested. The smaller shoot was 805 g and the bigger one was approximately 1200 g. These were tested microbiologically, organoleptically and chemically and the observations are placed below.
- The bigger shoot has a higher content of TPC (Total Plate Counts) and is positive for both Shigella and salmonella. So is the smaller shoot, though has a little less number of TPC (780 TPC/g Colony Forming Units).
- Chemically, the smaller shoot has a lesser content of HCN which indicates that as there is growth, the amount of HCN increases (until it reaches a limiting value). The brix (indicator of total soluble solids) and salt content are higher in the larger shoot, however the acidity is lesser then smaller shoot. (signifies ripening since after ripening, the acidity reduces).
- No Benzoic acid was detected in both the samples which indicate that Benzoic acid is not present in the raw shoot and is formed only after the shoot is peeled/cut/ packed.
- Organoleptically, the bigger shoot is bitterer than the smaller shoot ( a fact also stressed by the content of HCN). This indicates that on ripening, the amount of HCN generated in the shoot increases.
- Color of both the shoots, after peeling is white and the texture is hard, almost at par
Bamboo shoots with water (in Nylon and in PP)
- The shoots were packed in nylon as well as in poly propylene to check the variations due to packaging material. In which the shoots are packed. The samples were kept at three temperatures – 5o C, 37o C and at 55o C .
Bamboo shoots in water with Nylon
- Both the shoot and the water, in which the shoots were packed, were analysed.
- Chemical analysis showed that the TSS (brix) increased on storage, from 4th day to 7th day which indicates aging on storage. However, afterwards, the brix was more or les constant with only minor fluctuations (D 5 – 1.4, D7 - 1.2, D10 - 1.4). This indicates that some biochemical changes take place due to which insolubles are broken down in to solubles, which increases the brix. A possible route is conversion of higher carbohydrates (fibre, cellulose) in to smaller ones (sugars). This also indicated that microbial degradation has started taking place.
- For the shoot in PP based pouches, the brix on D10 was 1.8, (as compared to 1.4 for the nylon sample of the same day). This is indicative of more degradation in PP pouches as compared to the Nylon ones.
- Placed below is the chart showing the effect of brix on storage in packages containing bamboo shoots in water, packed in Nylon and PP pouches, and stored at different temperatures:
- This is a significant chart, since it indicates the extent of degradation and higher is the brix in the samples, the faster its shelf life is being reduced. Samples in PP have the highest brix which indicates that they are degrading faster then the one in Nylon packs.
- The thickness of the packaging material also may have a role to play since the nylon pouches have a thickness close to 90 microns and PP pouches are only 40 microns thick.
Effect of storage on acidity:
- The chart below reflects the effect of storage on acidity of the samples from day 4 to day 14 in packages stored at different temperatures.

- For packs in Nylon, stored at 37o C, the acidity is less on 14th day then the value obtained on 4th day. However, all the Nylon packs are stable even after 14 days and are showing good results organoleptically.
- Comparing the acidity on 10th day (Nylon/37 o C) with that of PP pouches stored at 37o C, PP reported a higher value. Also, the values for PP/37 o C and PP/55 o C are higher on 10th day ( though the difference is not significantly high) . PP/ 5 o C has lesser acidity on 10th day then respective Nylon pack, and is organoleptically found to be better then the other PP packs (at 37 o C or 55 o C).
Effect of storage on pH
- Enclosed is the effect of storage on the pH. pH ( a measure of H+ ions) is inversely roportional to acidity. More is the acidity lesser is the pH. The values for nylon/37 o C reflect that the acidity is reducing on storage for 14 days. For Nylon/5 o C, acidity is increasing on storage .
- PP/5 o C was organoleptically not suitable on 10th day, since acidity is very low. This may be a reason for spoilage of the sample. Also, PP/37 o C was also effected by 10th day and had a low acidity this sample was also discolored on 10th day.
- Correlating the acid content and the organoleptic analysis, it may be concluded that more acidity is helping the sample to stay better for longer time.
Effect of storage on HCN content:
- The effect of percentage of HCN on the packages packed in Nylon and PP, at different temperatures are drawn below :

- As can be seen from the values of HCN for Nylon/37 o C and Nylon/5 o C, the values fluctuate and values on D-14 (in case of Nylon/37 o C ) and D 21 (in case of Nylon/5 o C ) are less then the ones at the beginning of storage period (D-4 and D-7 respectively for Nylon/37 o C and Nylon/5 o C).
- The PP samples (5o C, 37o C and 55o C), though have higher values of HCN but still are organoleptically, did not perform as good as Nylon/37o C. This is contradictory since higher HCN content acts as deterrent and should maintain organoleptic quality for more no. of days. A reason for this behavior, independent of Conc. of HCN could be that the difference in the values of HCN is not very significant.
- HCN is naturally found in many fruits and vegetables used extensively for fumigation of bananas and citrus fruit infested with insects. Raw bamboo shoot has HCN in it. The level of cyanogenetic glucosides up to 500 ppm (0.5%) in foods is considered to be of no health hazard. The values of HCN in the above chart indicate that the shoot is safe for consumption. Even the concentrations of HCN in raw shoots (0.03%-0.06%) are well below this level.
Effect of storage on Benzoic Acid
- Benzoic acid and its salts are commonly used as preservatives for foods having lower pH (preferably close to or less then 4.5). Thus it will also act as a preservative for packed bamboo shoots. At this pH, fungi and molds are the common organisms which can spoil the shoot, thus Benzoic acid can act as effective deterrent. The percentage of BA in the Nylon packs vary from 0.0320 – 0.0453% .
- The reported concentrations to kill fungus are in the range of 0.15 – 0.20 % but these are the values for the benzoic acid added to food and not for the one naturally generated (for which the requirements may be lower).

- The Benzoic acid (BA) was not detected in raw shoots and on processing them, the BA concentration increased from 320 to 455 ppm from 4th day to 14th day of storage in Nylon packs. The values of BA in samples stored for 10 days do not differ significantly, though it is slightly lower in PP packs (which reflects at the less resistance and hence more deterioration, which is also observed during Organoleptic tests).
Microbiology of stored shoots
- The shoots in Nylon packs stored at 37 degrees showed good results microbiologically (refer to the chart) and were organoleptically, also suitable. TPC (An indicator of various microbes that are there in food), Salmonella, Shigella and Coliforms (indicators of contamination) were measured.
- On storage, as the antimicrobial substances (HCN, Benzoic Acid etc.) are released in to the pack, the TPC reduces drastically (25 cfu/g). Salmonella, Shigella and Coliforms which was detected in the raw shoots was not found in samples on storage. The reason may be the increase in acidity on storage and the release of antimicrobials in stored samples, which checked the microbes in stored samples.
- As per the chart, the Total Plate Counts (TPC) for PP/55 o C and PP/37 o C (too numerable to count) were high. These samples also did not fare well organoleptically on 10 days of storage. The analysis of PP/5 o C could not be done since the samples was torn and could not be analysed.
- The packs kept in PP showed a high microbial load, the sample at 37 o C degrees showed high TPC and high coliforms (which indicate contamination through touching and handling). This sample organoleptically was not adjudged as a good one since it showed discoloration on 10 days of storage.
- PP pack stored at 55 o C also showed high total viable counts and was discolored by 10th day.
- However, considering the similarity of figures in terms of acidity, HCN and Benzoic Acid, similar quantities are being generated in the two kinds of packs, the Nylon and the PP ones. But the samples in PP are degrading faster which indicates that the packaging material is not a good protector and is permitting the growth of microbes in the pack, leading to degeneration. Also, contamination during packaging could be another reason, as there were many people around while packaging (particularly during the handling of the packs of PP).
Organoleptic studies
- The samples were analysed organoleptically after fixed time intervals. Colour was noticed visually, the sample was eaten in raw form for noting the taste and texture was noted by touching with hand.
- The nylon packs (37o C up to 14 days, 55o C up to 5 days and 5o C for 21 days) were suitable organoleptically and did not show any digression from the organoleptic behavior of fresh shoot, which is slightly bitter, white in appearance and good in texture. Whereas the samples stored in PP pouches were not suitable on 10 days of storage.
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Among the three samples of PP, the one stored at 5o C was the best (only slight discoloration) then the other two (PP at 37o C and 55o C), which were completely discolored. This indicates that
- A higher thickness of PP should be used to preserve shoots
for 10 days
- Shoots if need to be preserved in this kind of PP (of 40 micron thickness) , should be kept for less number of days, the optimum time may be seven days and preferably should be stored at lower temperatures
Shoots without water
- Shoots without water were stored in Nylon and PP packs and were observed for changes in microbial, chemical and organoleptic parameters over a period of 10 days. All the samples were bitter in taste.
- Bamboo Shoots without water showed slight discoloration over a period of 10 days and the texture was also soft as compared to the normal, slightly hard texture, as observed in the packs kept in nylon pouches, with water. PP samples (both at 37o C and at 55o C) deteriorated and the one at 37 o C was only slightly discolored (creamy discoloration) whereas the one at 55o C was totally discolored (yellowish) and both softened on 10th day of observation. There was also formation of gas in the PP at 55 o C.
- Microbiologically, the TPC was higher in both the Nylon (130) and in PP (220) kept at 55o C. The least TPC was in Nylon/37o C (80) and PP/37o C reported a slightly higher value (95). No coliforms, salmonella and Shigella were detected in any of the samples.
- Nylon/37o C reported the highest acidity (0.38%) and the lowest HCN content (0.037%) . The acidity of other samples was very close to each other (0.27 %, 0.24 %, 0.26%). The Benzoic Acid content was also in close range for the four samples (417 – 479 ppm). The nylon packs had higher benzoic acid content then PP packs, similar to the pattern observed in nylon packs with water.
Microbial and chemical analysis of potable water
- The potable water was tested microbiologically and it showed a very high TPC count and also indicated the presence of E . coli. Salmonella and Shigella were also present I in this sample. Thus the water was not of good quality microbiologically and may have hastened the spoilage process. Chemically, it was high on hardness (255 mg/litre) and had high total dissolved solids.
- It should be taken into account that the water which is to be used for packing should be clean, potable and preferably fresh water.
Conclusions:
Bamboo Shoots in water can be stored at room temperatures (37 degrees), in Nylon packs for more than 14 days without any loss of texture, flavour and colour while retaining their natural bitter characteristic taste. Such samples if stored at 5o C can stay good for 21 days without any change in organoleptic parameters.
- On comparing the packs in Nylon with that of PP, the chemical components (acidity, Benzoic acid and HCN content) don’t show huge variations (though acidity and Benzoic Acid are visibly higher in Nylon packs) whereas there is a significant difference in the microbial profile; the TPC is very high for the PP packs.
- The shoots are no longer toxic on storage, even on the fourth day of storage since the HCN content is well below limit. Even the raw shoot doesn’t have HCN in enough quantity to cause any toxic effects.
- HCN and Benzoic Acid together act as effective antimicrobials and prevent the packed shoot from spoilage.
- Shoots packed in PP, though in this study, could not stand storage for 10 days but a packaging material of thickness at par with Nylon (90 micron) used in the study, may remain stable for at least 10 days. This is important since the cost of PP is very less as compared to that of Nylon based packaging material. Shoots, if need to be preserved in this kind of PP (of 40 micron thickness) , should be kept for less number of days, the optimum time may be seven days and preferably should be stored at lower temperatures.
- Between raw shoots, the bigger one (1200 g) had a higher content of HCN then the smaller one, which indicates that on aging the amount of HCN goes on increasing. Also, the bitterness increases with the size, since the larger shoot was found to be bitterer. Also the bigger shoot had lesser acidity then the smaller shoot.
- Packs, without water, both in Nylon and in PP were not stable organoleptically on 10 days of storage and thus shoots should only be packed in water. This observation reiterates the fact that the shoots need to be prevented from oxidation by gases, which can lead to spoilage.
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