Physico-chemical and sensory attributes in conjunction with multivariate analysis of two potato (Solanum tuberosumL.) cultivars after 90 days of storage: an exploratory authentication study

Determination of the effect of abiotic stress on the oxidative potential of edible potato tubers

Stress factors occurring during the growing season and potato storage, can negatively affect the quality of tubers, including an increased tendency to enzymatic darkening. Abiotic stress due to water shortage is a major factor limiting agricultural production. The purpose of the study was to determine the effect of cultivation technology based on the use of biostimulant, hydrogel and irrigation as well as storage on the propensity to darkening and the content of sugars and organic acids. The results show that genotypic and technological variability in interaction with growing season conditions had a significant (p < 0.05) effect on the oxidative potential (OP) of potato tubers. The Denar cultivar, compared to the 'Gardena', was characterized by a lower tendency to enzymatic darkening. Application of biostimulant and hydrogel generally contributed to lowering the oxidative potential of the tested cultivars. The application of anti-stress agents had no effect on organic acid content. The long-term storage caused an increase in the content of total sugars (TS) (22%), reducing sugars (RS) (49%), chlorogenic acid (ACH) (11%), and loss of ascorbic acid (AA) (6%) in the tubers which contributed to an increase in the oxidative potential of potato tubers (16%). The correlation coefficients obtained (p < 0.05) confirm the dependence of OP on the concentration of organic acids.

Fresh-cut potato quality and sensory: Effect of cultivar, age, processing, and cooking during storage

This work examined the influence of cultivar, tubers' age, antibrowning agent, package atmosphere, and storage time on fresh-cut potatoes' (FCPs) physical, chemical, and sensory properties. Potato slices of cv. Birgit and Lady Claire tubers sampled during the first, fifth, and ninth months of storage were dipped in solutions of (1) sodium chloride (1%) and (2) sodium ascorbate (2%), and stored for 8 days in (1) vacuum and (2) active modified atmosphere (MAP) (10.0% CO₂ , 3.0% O₂ , and 87.0% N₂ ) at 10 °C. During storage, O₂ and CO₂ content (%) within packages was measured and samples were analyzed for weight loss, total solids (TS) and soluble solids (SS), pH, color, texture, and sensory properties of raw, boiled, fried, and baked FCP. Results showed that 9 months' aging had a significant impact on almost all investigated FCP properties, but differences among first, fifth, and ninth months were numerically feeble for some parameters in raw samples: TS changed from 22.14% to 20.98%, SS 5.53% to 6.93%, pH 6.02 to 5.98, L^* 70.10 to 68.87, C^* 35.75 to 36.70, H° 89.29 to 88.15, and firmness 7.25 to 8.13N. Furthermore, 9 months of aging had no significant influence on the characteristic odor of raw, boiled, fried, and baked FCP and characteristic taste of fried and baked FCP, whereas boiled FCP characteristic taste remained unchanged for 5 months of aging. Fried FCP was better sensory evaluated than baked ones, cv. Birgit was more suitable for the FCP production compared to cv. Lady Claire as well as vacuum packaging and sodium ascorbate better preserved samples quality and sensory than sodium chloride and MAP. PRACTICAL APPLICATION: This study could be helpful to fresh-cut potato (FCP) producers because results indicate that for FCP processing, along with the selection of cultivar, antibrowning agent, and packaging type, tubers' age also requires attention. A further contribution of this research is related to the adequate way of FCP cooking, where frying shows the best results according to the quality and sensory assessment.

Effect of steam cooking on the residual enzymatic activity of potatoes cv. Agria

BACKGROUND

The aim of this work was to study the influence of steam cooking on pectin methylesterase (PME) and endogenous α- and β-amylase activities in different tissues (cortex and pith) of raw and heat-treated potatoes cv. Agria. Three different cooking temperatures were chosen (55, 70 and 85 °C). For each cooking trial, time-temperature profiles were recorded and the degree of cooking was expressed in terms of cooking factor.

RESULTS

Steam cooking contributed to significantly activate PME at 55 °C and to reduce its activity at the final processing temperature (85 °C), with the highest amount in the cortex (0.3745 ± 0.0007 µmol galacturonic acid (GA) g(-1) fresh weight (FW) min(-1) ) compared with the pith (0.2617 ± 0.0012 µmol GA g(-1) FW min(-1) ). The presence of heat-labile and heat-stable isoforms of PME in the considered potato tissues was also assumed. Heat treatment by steam resulted in a significant decrease in endogenous α- and β-amylase activities in both tissues compared with the raw potato, though without complete deactivation. Starch-degrading enzymes were also found to be differently distributed in the raw tuber.

CONCLUSION

Steam cooking affected in different ways the assessed residual enzymatic activity in the considered tissues of potatoes cv. Agria. Further research is needed to confirm the results obtained.

Studies of sugar composition and starch morphology of baked sweet potatoes (Ipomoea batatas (L.) Lam)

Sugar composition of seven sweet potato cultivars was successfully analyzed. Fresh CYY95-26 sweet potatoes had the highest (8.41%) total sugar content while TNG73 had the lowest (4.5%). For these fresh sweet potatoes, maltose content was very low (0 ~ 0.39%). Because 49.92 ~ 92.43% of total sugars were sucrose, sucrose was the major sugar composition of fresh sweet potatoes. After the baking treatment, the total sugar content of baked sweet potatoes was dramatically increased due to the formation of maltose. The maltose content significantly increased from 0 ~ 0.39% to 8.81 ~ 13.97% on dry weight basis. Therefore, maltose should be included in calculating the total sugar content. Electronic micrographs of fresh sweet potato samples showed that the size of starch granules was generally less than 20 μm. After the baking treatment, starch granules completely gelatinized.

Appropriateness of culinary preparations of potato (Solanum tuberosum L.) varieties and relation to sensory and physicochemical properties

BACKGROUND

Appropriateness of potatoes for culinary preparations is defined as the optimal use of a given variety for a specific culinary preparation. The aim of this study was to examine the sensory attributes and physicochemical characteristics (dry matter content, starch properties, instrumental texture) of 11 potato varieties in relation to their appropriateness for boiling, oven-frying or mashing. The reproducibility of appropriateness was studied by including the effect of two growing conditions and yearly variation combined with internal references.

RESULTS

The potato varieties, tested by 31 evaluators in two years, showed three groupings differing in appropriateness, which could be explained by a few sensory attributes: yellowness, mealiness, creaminess and butter taste. The physicochemical data showed a large variation of 23-25% in dry matter content, amylose content and starch granule size and an extreme variation in texture hardness. High reproducibility was found in the ranking of potatoes across years and culinary preparations. Hence, if a variety was judged well appropriate for boiled potatoes, it was also judged well appropriate as mashed or oven-fried potatoes.

CONCLUSION

This study showed the relevance of using sensory descriptors appropriateness in an objective manner. A few sensory descriptors can be used in consumer-labelling appropriateness of potatoes.

Exploratory sensory profiling of three culinary preparations of potatoes (Solanum tuberosum L.)

BACKGROUND

A consumer-oriented description of potato quality with regard to culinary preparation could increase potato consumption. The aim of this study was to investigate the sensory attributes in 11 potato varieties grown at two locations and used for three culinary preparations.

RESULTS

Sensory evaluation of the potatoes served either as boiled, oven-fried or mashed were performed using 15-19 descriptors for appearance, flavour and texture attributes. A principal component analysis revealed that 45% of the variation in the sensory data was related to variety differences, which was ascribed to variation in appearance, dry matter content and texture. Growing location also significantly affected appearance and texture.

CONCLUSION

The sensory panel judged the sensory attributes 'yellowness', 'hardness', 'adhesiveness' and 'moistness' to be important quality descriptors in all three culinary preparations. Internal references showed the high reproducibility of the sensory evaluations. The potatoes grown in a sandy location had higher content of dry matter compared to those grown in a clay location, affecting the quality. This study showed that it was possible to do reliable and reproducible sensory profiles in a potato material with a large span in quality. Sensory information based on few attributes can be used to describe culinary quality of potato varieties.