**3.2. Postharvest pod handling and kernel moisture content**

Moisture content of groundnut kernels greatly influences the growth of toxigenic fungi and subsequent aflatoxin contamination. The study has shown that different drying methods had different influences on the total kernel moisture losses at different experimental sites at different harvesting times. Moisture content of kernels from the A-Frame at both sites decreased from an average of 38–7%, within a 4-week period (**Figure 1**). These moisture contents were significantly different at (P ≤ 0.05) from each other. It was observed that kernel moisture loss was rapid just after harvesting compared to the other following weeks. This was attributed to the high water activity in the seeds just after harvesting than the following weeks, which resulted into increased diffusion rate of water from the seeds to the environment through evapotranspiration and thus leading to rapid loss of water.

Significant differences (P ≤ 0.05) were also recorded in kernel moisture loss of tarpaulin dried pods. The moisture content decreased from an average of 38–7%, within a 2-week period (**Figure 2**). It has been established that, using the tarpaulin drying method, kernel moisture loss was more rapid compared to using the A-Frame drying method. The reason behind this was that, with tarpaulin drying, pods were exposed to direct sunlight which resulted into rapid losses of kernel moisture within a short period of time, while for the A-Frame method, the kernels took a longer time to dry because the pods were facing inwards and away from the sunlight and soil and were covered by leaves. This ensured a good air circulation and slow but effective drying.

The study also revealed that the variety *JL-24* took a shorter period of time to dry compared to the other two varieties irrespective of the drying method. This could be attributed to the lower

**Figure 1.** Kernel moisture loss when using the A-Frame.

moisture content of the variety and the thinner layer of the shell. The variety *ICGV-SM-01514* took the longest time to dry irrespective of the drying method and this could be attributed to the thicker shell of the variety which led to slower moisture loss.

#### **3.3. Effect of harvesting time on groundnut aflatoxin contamination**

However, significant higher rainfall fell during H1, while H2 and H3 experienced a prolonged end of season drought. The mean daily air temperatures during the pod-filling period at PAN were higher ranging from 30 to 35°C by H1 to H3. Additionally, the location experienced very

Moisture content of groundnut kernels greatly influences the growth of toxigenic fungi and subsequent aflatoxin contamination. The study has shown that different drying methods had different influences on the total kernel moisture losses at different experimental sites at different harvesting times. Moisture content of kernels from the A-Frame at both sites decreased from an average of 38–7%, within a 4-week period (**Figure 1**). These moisture contents were significantly different at (P ≤ 0.05) from each other. It was observed that kernel moisture loss was rapid just after harvesting compared to the other following weeks. This was attributed to the high water activity in the seeds just after harvesting than the following weeks, which resulted into increased diffusion rate of water from the seeds to the environment through

Significant differences (P ≤ 0.05) were also recorded in kernel moisture loss of tarpaulin dried pods. The moisture content decreased from an average of 38–7%, within a 2-week period (**Figure 2**). It has been established that, using the tarpaulin drying method, kernel moisture loss was more rapid compared to using the A-Frame drying method. The reason behind this was that, with tarpaulin drying, pods were exposed to direct sunlight which resulted into rapid losses of kernel moisture within a short period of time, while for the A-Frame method, the kernels took a longer time to dry because the pods were facing inwards and away from the sunlight and soil and were covered by leaves. This ensured a good air circulation and slow but effective drying. The study also revealed that the variety *JL-24* took a shorter period of time to dry compared to the other two varieties irrespective of the drying method. This could be attributed to the lower

high relative humidity ranging from 75 to 85%.

30 Mycotoxins - Impact and Management Strategies

**3.2. Postharvest pod handling and kernel moisture content**

evapotranspiration and thus leading to rapid loss of water.

**Figure 1.** Kernel moisture loss when using the A-Frame.

Aflatoxin contamination levels among groundnut varieties at different harvesting times are presented in **Figure 3**. Significant differences (P ≤ 0.01) were observed in the mean aflatoxin contamination levels with physiological maturity (H2) having the lowest aflatoxin contamination levels (≤10 ppb). The highest aflatoxin contamination levels were recorded when

**Figure 2.** Kernel moisture loss when using tarpaulins.

**Figure 3.** Aflatoxin levels in groundnuts as affected by harvesting time.

harvesting was executed 10 days after physiological maturity (H3) (≥20 ppb) compared to when harvesting was executed 10 days before physiological maturity (H1) (≤15), which had considerably lower aflatoxin levels.

at the two study locations (**Tables 3** and **4**). The results showed that aflatoxin contamination of

Effect of Harvesting Time and Drying Methods on Aflatoxin Contamination in Groundnut in Mozambique

At Mapupulo Agricultural Research Center, the lowest aflatoxin contamination levels were found to be 3 and 4 ppb for the A-Frame and tarpaulin drying methods, respectively, harvested at physiological maturity. For Nampula Research Station, the lowest levels of aflatoxin contamination were found to be 2 ppb for both drying methods harvested at physiological maturity. Higher aflatoxin levels (≥25 ppb) were recorded when harvesting was executed 10 days after physiological maturity (H3) with respect to the drying methods. In summary, it has been established that the interaction of delayed harvesting and tarpaulin drying method resulted in higher aflatoxin contamination among the groundnut varieties than the interaction of delayed harvesting and A-Frame drying method. Overall, the interaction of harvesting time and A-Frame drying method resulted into lower aflatoxin contamination levels than the inter-

**H1 H2 H3**

http://dx.doi.org/10.5772/intechopen.77300

33

**H1 H2 H3**

ICGV-SM-01514 10bc 3c 25a JL-24 4c 4c 19ab

ICGV-SM-01514 17bc 10cd 42a JL-24 9cd 13c 25b

ICGV-SM-01514 2c 2c 21ab JL-24 10bc 1c 12b

ICGV-SM-01514 8bc 8bc 33a JL-24 19b 2c 22ab

the nuts started at H1 and significantly increased with delayed harvesting time (H3).

action of harvesting time and tarpaulin drying method.

**Drying method Variety Harvest timing**

A-Frame ICGV-SM-99568 3c 7bc 17b

Tarpaulin ICGV-SM-99568 16bc 4d 40ab

Means within a column followed by the same letter are not significantly different based on Tukey's test (**P < 0.01**).

**Table 3.** Groundnut aflatoxin levels as affected by the interaction of harvesting time and drying method at CIAM.

A-Frame ICGV-SM-99568 3c 2c 27a

Tarpaulin ICGV-SM-99568 18b 4c 32a

Means within a column followed by the same letter are not significantly different based on Tukey's test (**P < 0.01**).

**Table 4.** Groundnut aflatoxin levels as affected by the interaction of harvesting time and drying method at PAN.

Mean ± SE A-Frame 9 ± 4.03 Tarpaulin 16.5 ± 5.6

Mean ± SE A-Frame 10 ± 3.77 Tarpaulin 21 ± 5.17

**Drying method Variety Harvest timing**

The study also revealed significant differences in aflatoxin levels among the three groundnut varieties. The variety *JL-24* had the lowest mean aflatoxin contamination levels compared to the other two varieties. This could be attributed to the lower moisture content of the *JL-24* and the thin shell of the variety which led to rapid drying and minimized fungal invasion and subsequent aflatoxin contamination.

The study also revealed significant differences in aflatoxin levels among the three groundnut varieties. The variety *JL-24* had the lowest mean aflatoxin contamination levels compared to the other two varieties. This could be attributed to the lower moisture content of the *JL-24* and the thin shell of the variety which led to rapid drying and minimized fungal invasion and subsequent aflatoxin contamination. Furthermore, it was observed that at CIAM, the mean aflatoxin contamination levels of *ICGV-SM-99568* (14.5 ppb) were significantly lower compared to that of *ICGV-SM-01514* (17.9 ppb). A similar trend of results was observed at PAN; however, at this location, *ICGV-SM-01514* had the lowest mean aflatoxin contamination levels (12.3 ppb) compared to (14.3 ppb) for the variety *ICGV-SM-99568*.

### **3.4. Effect of drying method on groundnut aflatoxin contamination**

Significant differences were observed in aflatoxin contamination levels among the groundnut varieties as a result of drying method. Lower levels of aflatoxin were recorded by the use of A-Frame compared to the tarpaulin drying method (**Figure 4**). However, except for the variety *ICGV-SM-01514* (26 ppb) at CIAM, the aflatoxin contamination levels for the groundnut varieties were lower than 20 ppb as a result of both drying methods, and thereby, showing the effectiveness of the two drying methods in prevention of aflatoxin contamination.

Significant differences in aflatoxin contamination levels were also observed among the groundnut varieties as a result of the interaction between harvesting time and drying methods

**Figure 4.** Effect of drying method on groundnut aflatoxin contamination.

at the two study locations (**Tables 3** and **4**). The results showed that aflatoxin contamination of the nuts started at H1 and significantly increased with delayed harvesting time (H3).

harvesting was executed 10 days after physiological maturity (H3) (≥20 ppb) compared to when harvesting was executed 10 days before physiological maturity (H1) (≤15), which had

The study also revealed significant differences in aflatoxin levels among the three groundnut varieties. The variety *JL-24* had the lowest mean aflatoxin contamination levels compared to the other two varieties. This could be attributed to the lower moisture content of the *JL-24* and the thin shell of the variety which led to rapid drying and minimized fungal invasion and

The study also revealed significant differences in aflatoxin levels among the three groundnut varieties. The variety *JL-24* had the lowest mean aflatoxin contamination levels compared to the other two varieties. This could be attributed to the lower moisture content of the *JL-24* and the thin shell of the variety which led to rapid drying and minimized fungal invasion and subsequent aflatoxin contamination. Furthermore, it was observed that at CIAM, the mean aflatoxin contamination levels of *ICGV-SM-99568* (14.5 ppb) were significantly lower compared to that of *ICGV-SM-01514* (17.9 ppb). A similar trend of results was observed at PAN; however, at this location, *ICGV-SM-01514* had the lowest mean aflatoxin contamination levels

Significant differences were observed in aflatoxin contamination levels among the groundnut varieties as a result of drying method. Lower levels of aflatoxin were recorded by the use of A-Frame compared to the tarpaulin drying method (**Figure 4**). However, except for the variety *ICGV-SM-01514* (26 ppb) at CIAM, the aflatoxin contamination levels for the groundnut varieties were lower than 20 ppb as a result of both drying methods, and thereby, showing the

Significant differences in aflatoxin contamination levels were also observed among the groundnut varieties as a result of the interaction between harvesting time and drying methods

effectiveness of the two drying methods in prevention of aflatoxin contamination.

(12.3 ppb) compared to (14.3 ppb) for the variety *ICGV-SM-99568*.

**Figure 4.** Effect of drying method on groundnut aflatoxin contamination.

**3.4. Effect of drying method on groundnut aflatoxin contamination**

considerably lower aflatoxin levels.

32 Mycotoxins - Impact and Management Strategies

subsequent aflatoxin contamination.

At Mapupulo Agricultural Research Center, the lowest aflatoxin contamination levels were found to be 3 and 4 ppb for the A-Frame and tarpaulin drying methods, respectively, harvested at physiological maturity. For Nampula Research Station, the lowest levels of aflatoxin contamination were found to be 2 ppb for both drying methods harvested at physiological maturity.

Higher aflatoxin levels (≥25 ppb) were recorded when harvesting was executed 10 days after physiological maturity (H3) with respect to the drying methods. In summary, it has been established that the interaction of delayed harvesting and tarpaulin drying method resulted in higher aflatoxin contamination among the groundnut varieties than the interaction of delayed harvesting and A-Frame drying method. Overall, the interaction of harvesting time and A-Frame drying method resulted into lower aflatoxin contamination levels than the interaction of harvesting time and tarpaulin drying method.


Means within a column followed by the same letter are not significantly different based on Tukey's test (**P < 0.01**).

**Table 3.** Groundnut aflatoxin levels as affected by the interaction of harvesting time and drying method at CIAM.


Means within a column followed by the same letter are not significantly different based on Tukey's test (**P < 0.01**).

**Table 4.** Groundnut aflatoxin levels as affected by the interaction of harvesting time and drying method at PAN.
