Evaluation and storage stability of potato chips made from different varieties of potatoes cultivated in Pakistan

Effect of harvest-to-cooling delay and precooling on Kufri Jyoti (Solanum tuberosum) potato quality

Precooling is the rapid removal of field heat in harvested crops to preserve their quality and increase their shelf life. The following study was conducted to understand the importance of precooling and to optimize the precooling condition to extend the storage life of potatoes. Therefore, the study was divided into two components. In the first part, the Kufri Jyoti potatoes were subjected to field heat for 0-64 h, then were precooled for 48 h before sending to cold storage for 60 days. The results demonstrated that when the time delay was doubled, starch content (SC) decreased by 15.86%, reducing sugar content (RSC) increased by 32.71%, ascorbic acid content (AAC) decreased by 5.94% and total plate count (TPC) increased by 20.06%. Microstructural changes in potatoes due to the exposure to field heat were visible in SEM images. These results suggested a decrease in the quality of potatoes with an increase in time delay between harvest and cooling. In the second part of the study, the potatoes were precooled for 48 h at different temperatures (T) (6 °C, 8 °C, and 10 °C) and relative humidity (RH) (87%, 91%, and 95%), and their effect was studied on the same quality parameters after storage. Regression models were developed for each response, and models with non-significant lack of fit were selected for optimization. The analysis of the observations has shown that precooling aided in better quality retention of potatoes during cold storage.

Fungal composition, quantification of mycotoxins, and enzyme activity in processed Solanum tuberosum Linn (potato) products stored at different relative humidity

AIM

Postharvest loss of potatoes at the peak of harvest is of global concern. This study aimed to determine the quality of stored processed potato products based on fungal composition, mycotoxin contamination, and fungal enzyme activity.

MATERIALS AND METHODS

Potato products from three cultivars (Caruso, Marabel, and Nicola) were grouped as peeled or unpeeled, oven- or sun-dried, and all samples were in flour form. Samples were incubated separately for 6 weeks at 25%, 74%, and 87% relative humidities (RH) at 25°C. The pH, moisture content (MC), visible deterioration, mycotoxin, fungal identity by DNA sequencing, and enzyme activity were determined.

RESULTS

Results of grouped products (based on variety, drying, and peeling method) revealed that MC increased in the oven-dried samples and the pH value reduced after incubation. About 26% of the products at 87% RH showed visible deterioration, low amounts of fumonisin were detected in fermented potato product and nine fungal genera were identified across the three RH levels. Enzyme activities by Aspergillus niger, Fusarium circinatum, and Rhizopus stolonifer isolates were confirmed.

CONCLUSION

RH influenced deterioration and fungal activities in some stored processed potato products. Low levels of fumonisin were detected.

Extraction and characterization of starch from low-grade potatoes and formulation of gluten-free cookies containing modified potato starch

Potatoes are among the leading staple crops due to nutritional value and high demand. The undersized and damaged potatoes are considered low grade and mainly dumped as a waste or used in animal feed. The study aimed to extract starch from low grade potatoes, its modification to improve the starch properties and formulation of gluten free cookies using modified starch (MS). The starch was extracted from low-grade potatoes of three varieties known as Asterix, Kruda and Mosaic, using the water steeping method. The native starch (NS) was modified using lintnerization and repetitive autoclaving. MS contains high amylose content which is associated with health benefits. NS and MS were characterized for amylose content, color attributes, granular morphology, water solubility index (WSI), water absorption index (WAI), thermogravimetric analysis (TGA) and Fourier transform infrared spectrometer (FTIR) analysis. Gluten-free cookies were formulated by adding potato NS and MS. The cookies were characterized by sensory evaluation, proximate and textural analysis. The starch yield extracted from three different varieties of potatoes i.e. Asterix, Kruda, Mosaic was 11.53%, 11.32% and 11.24%, respectively. The amylose content of potato starch was significantly (p < 0.05) increased for all varieties (33.61-37.74%) after modification of NS, which was in the range of 25.71-26.60% for different potato varieties. The granules of MS were observed as amorphous structures in comparison to NS granules with smooth surfaces. The addition of MS significantly (p < 0.05) decreased the hardness of the cookies in comparison to NS. Overall, no significant difference was observed in the sensory attributes of control, NS and MS containing cookies. Therefore, in comparison to other dietary fibers, MS can be used as a functional ingredient in food products without compromising the texture and sensory attributes.

Dry Matter, Starch Content, Reducing Sugar, Color and Crispiness Are Key Parameters of Potatoes Required for Chip Processing

To make potato production more sustainable for smallholder farmers, product diversification through processing is critical. On the other hand, the processing sector mandated some stringent standards in order to maintain product quality, hence potato quality evaluations are required for chip processing industries. Specific gravity, starch, reducing sugars, tuber dry matter, and chip color are all important characteristics to consider for processing. This study was designed to find suitable potato varieties with satisfactory attributes for processing chips, in comparison with other processing potato varieties. Keeping this in mind, the study was performed during the winter season of 2019–2020 and 2020–2021 in Bangladesh. Six processing types of potato varieties viz. BARI Alu-25 (Asterix), BARI Alu-28 (Lady Rosetta), BARI Alu-29 (Courage), BARI Alu-68 (Atlantic), BARI Alu-70 (Destiny), and BARI Alu-71 (Dolly) were evaluated for different quality parameters (specific gravity, dry matter, starch content, reducing sugar, chip color, and crispiness). The result of the study showed an ample variation in the studied parameters among the potato varieties. Among the varieties, BARI Alu-28 (Lady Rosetta) and BARI Alu-29 (Courage) were found better for all the quality parameters, such as dry matter, starch, reducing sugar, chip color, and crispiness, and could be recommended for the processing industries.

The Physico-Chemical and Sensory Characteristics of Coloured-Flesh Potato Chips: Influence of Cultivar, Slice Thickness and Frying Temperature

Coloured potato chips, due to a higher concentration of bioactive compounds, may be healthier compared to traditional chips. This study examined the effect of cultivar and different slice thicknesses and frying temperatures on the physico-chemical and sensory characteristics of coloured potato chips. Potatoes chips were prepared from three coloured potato cultivars. Frying experiments were conducted at 160 and 180 °C using potato slices with thicknesses of 1.00 and 2.00 mm. The quality of the raw potatoes tubers and chips were estimated. A principal component analysis was applied to describe the differences in the physico-chemical characteristics between the potato chip samples processed with different conditions. The results showed that, significantly (p < 0.05), the highest amounts of total phenolic content, total anthocyanins, dry matter and starch were accumulated in raw tubers of potato cv. Blaue Anneliese. The highest amount of total phenolic content and anthocyanins was found in 1 mm chips of cv. Blaue Anneliese fried at 160 °C. An increased frying temperature significantly (p < 0.05) decreased the content of these compounds. The amount of fat in the chips was higher when they were fried at 160 °C than at 180 °C. Chips processed from potatoes cvs. Blaue Anneliese and Rosemarie showed a typical colour as a raw material. The hardness of the chips significantly (p < 0.05) increased with an increase in slice thickness. The flavour, odour and colour of the 1 mm chips of cv. Blaue Anneliese fried at 180 °C gained the highest rating.