Effect of cultivar and storage time on the volatile flavor components of baked potato

The Impact of the Foliar Application of Amino Acid Aqueous Fertilizer on the Flavor of Potato Tubers

The quality of the flavor of potatoes is a crucial determinant in the commercial success of a potato variety. Plant nutrition promotes the synthesis of amino acids, and the application of exogenous amino acids has the potential to enhance the flavor quality of potatoes. In this experiment, Dian Shu 1418 and Dian Shu 23 were used as the materials, and different amino acid foliar spray trials were designed. The free amino acid content in potato tubers is determined based on high-performance liquid chromatography, and volatile tuber flavor compounds are detected using gas chromatography-mass spectrometry. The results showed that the amino acid foliar spray effectively increased the content of glycine, methionine, and phenylalanine in the tubers, subsequently increasing the levels of 2,3-dimethyl-pyrazine and 2-ethyl-3-methyl-pyrazine, enhancing the roasted fragrance characteristics of the potatoes. The experimental results provide a reference for cultivating flavor enhancement in potato tubers.

The Impact of the Individual and Combined Application of Phosphorus and Sulfur Fertilizers on Potato Tuber Flavor

Sulfur and phosphorus are important plant nutrients required for potato growth, influencing the synthesis of primary metabolites that serve as the material foundation of potato flavor quality. However, little is known about the effects of sulfur and phosphorus application on potato tuber flavor. This study experimentally compared the effects of the individual and combined application of phosphorus and sulfur fertilizers on the flavor of potato tubers. The research examined the sensory characteristics of flavor under various fertilization methods, investigated changes in the types and contents of volatile flavor compounds, and conducted analyses on flavor precursor compounds. The experimental results showed that the application of phosphorus and sulfur fertilizers, either individually or in combination significantly increased the content of linoleic acid and linolenic acid. After the combined application of phosphorus and sulfur fertilizers, the starch and the reducing sugar content also significantly increased. (E,E)-2,4-Nonadienal and Decanal are closely correlated with fatty acid content. Dimethyl sulfide and Trimethyl sulfide contents are significantly related to methionine content. This also significantly enhances the fatty taste characteristics of the tubers but weakens the potato flavor characteristics. Hence, the application of phosphorus and sulfur can affect the accumulation of primary metabolic products in tubers, thereby affecting flavor quality. Compared with the individual application of phosphorus or sulfur fertilizers, when phosphorus fertilizer is applied at 180 kg·ha-1 and sulfur fertilizer at 90 kg·ha-1 in combination, it can further enrich the roasted flavor characteristics of potatoes and maximize the enhancement of potato flavor quality. This provides valuable theoretical support for achieving high-quality agricultural development.

Development and Quality Characteristics of Elderly-Friendly Pulpo a La Gallega Prepared Using Texture-Modified Octopus (Octopus vulgaris) Arms

Considering the need for developing new senior-friendly processed seafood, this study aimed to develop octopus pulpo with high preference and excellent quality characteristics for elderly individuals by optimizing the vinegar immersion and sous vide softening treatment conditions for octopus (Octopus vulgaris) arms. The optimal sous vide heating temperature (70.0-100.0 °C), time (69.5-170.5 min), and vinegar concentration (0.2-0.8%) were established using response surface methodology (RSM). The pulpo prototype was produced using an octopus arm softened under optimal conditions and seasoned with a potato and olive oil sauce. The physicochemical and nutritional properties of the prototype were evaluated, followed by sensory evaluation and safety assessments. The hardness of softened octopuses obtained by 0.48% vinegar immersion and sous vide treatment (84.3 °C, 139.8 min), determined using RSM, was 394.5 × 1000 N/m2, showing a reduction of 83.0%; this was confirmed by electron microscopic observation. The texture of the pulpo prototype with softened octopus arms showed the highest preference (8.4 points) and high physicochemical and nutritional properties. Overall, the octopus pulpo a La Gallega prototype produced using texture-modified octopus arms was suitable for consumption by elderly people with chewing disorders and could help improve their quality of life.

Development of a Flavor Fingerprint Using HS-GC-IMS for Volatile Compounds from Steamed Potatoes of Different Varieties

The variations in flavor substances across different varieties of steamed potatoes were determined by headspace-gas chromatography ion mobility spectrometry (HS-GC-IMS) combined with sensory evaluation. Results showed that 63 representative compounds, including 27 aldehydes, 14 alcohols, 12 ketones, 4 esters, 2 furans, 1 acid and others, together acted as contributors to the flavors in steamed potatoes. Analysis found that species and concentrations of aldehydes, alcohols and ketones in six varieties were the most abundant. In addition, esters, furans and acid were also responsible for flavor. PCA results showed that volatile compounds in Atlantic, Longshu No. 23, Longshu No. 7 and Longshu No. 14 were similar, while Russet Burbank and Longshu No. 16 had distinct characteristic volatiles, which was consistent with sensory evaluation. The combination of sensory evaluation and HS-GC-IMS provided useful knowledge for charactering volatile compounds of steamed potatoes from different varieties, and also demonstrated the promising application of HS-GC-IMS in the detection of potato flavor with various cooking methods.

Comparison of the Effects of Potassium Sulphate and Potassium Chloride Fertilisation on Quality Parameters, Including Volatile Compounds, of Potato Tubers After Harvest and Storage

Potatoes are an important staple food with high yield potential and great nutritional value. Potassium (K) fertilisation can increase both tuber yield and quality, but its effects differ depending on the K fertilisation form. Potatoes are known to be chloride sensitive, since chloride ions can influence, for example, the starch content. Therefore, fertilisations shortly before planting using potassium sulphate (K₂SO₄) are often recommended instead of potassium chloride (KCl). However, the use of different fertilisation forms is contradictory, and the chloride sensitivity of potatoes remains unclear. To examine this issue in more detail, a 2-year field experiment using two cultivars, "Laura" and "Marabel," was conducted. K fertilisation with 240 kg K₂O as K₂SO₄ and KCl was applied, and the control remained unfertilised. Quality traits, including internal and external parameters, were analysed after harvest and after 5 months of storage at 6°C. The results revealed minor effects on yield, but the starch content and ascorbic acid concentration were reduced due to the KCl supply. Furthermore, the reducing sugar concentration in tubers increased during storage more after KCl compared to K₂SO₄ fertilisation. Moreover, volatile compounds were affected by the K fertilisation form, with higher levels of lipid-derived off-flavour compounds after KCl application. However, the effects of cultivation year, cultivar, and storage interacted with the influence of the fertilisation form. In summary, KCl fertilisation can disadvantageously influence several quality traits, but the use of potato cultivars should also be considered when recommending fertilisers.

Determination of 3-Alkyl-2-methoxypyrazines in Green Coffee: A Study To Unravel Their Role on Coffee Quality

Although a high concentration of some 3-alkyl-2-methoxypyrazines in green coffee has been associated with an off-flavor described as potato taste defect (PTD) or "peasy" defect, affecting the product quality, the natural concentration of these compounds in good quality coffee beans has never been the subject of a detailed study. 3-Isobutyl-2-methoxypyrazine (1), 3-sec-butyl-2-methoxypyrazine (2), 3-isopropyl-2-methoxypyrazine (3) concentrations were determined on a range of selected, good quality green coffees of different botanical species (arabica and robusta) and geographical origin. The presence of the three methoxypirazines was confirmed in all samples; the concentration of compound 1 was significantly higher than those of compounds 3 and 2, showing a geographical-origin-dependent variability. This whole set of experimental data was then used as a reference to ascertain the PTD occurrence in "suspected PTD" and insect-damaged samples. Compound 3 was the main indicator of defectiveness, with a main variability in its concentration in insect-damaged samples, suggesting that the insect-induced damage is not a sufficient condition to induce the off-flavor. The analysis in fresh potatoes, carried out to disclose the origin of the term used to describe the PTD in coffee, showed a very low concentration of 3-alkyl-2-methoxypyrazines. However, the relative prevalence of compound 3 on the total of 3-alkyl-2-methoxypyrazines could be related to the characteristic "potato" flavor frequently evoked to describe the sensory perceived defect in coffee.

Effects of plasma treatment on the oxidative stability of vegetable oil containing antioxidants

Plasma, the fourth stage of matter, is a partially or wholly ionized state of gas. Degree of lipid oxidation and effects of antioxidants were evaluated in bulk oils at plasma treatment. Significant changes in the conjugated dienoic acid were induced after 10 min of plasma treatment, which corresponded to treatment for 2.5 h at 100 °C and 48 h at 60 °C. Tocopherol stability in the stripped corn oil was significantly higher than that in medium-chain triacylglycerol after the plasma treatment. The antioxidant capacities of 10 μM of α-tocopherol and sesamol were higher than that of β-carotene, and synergistic effects among α-tocopherol, sesamol, and β-carotene were not observed. Added α-tocopherol and sesamol decreased CDA formation by 33 and 30% compared to control samples after plasma treatment. Moisture content in oils decreased significantly about 20% moisture after 6 min plasma treatment. Lipid oxidation could be an important issue in plasma-treated lipid-rich products.

Next-Gen Approaches to Flavor-Related Metabolism

Although flavor is an essential element for consumer acceptance of food, breeding programs have focused primarily on yield, leading to significant declines in flavor for many vegetables. The deterioration of flavor quality has concerned breeders; however, the complexity of this trait has hindered efforts to improve or even maintain it. Recently, the integration of flavor-associated metabolic profiling with other omics methodologies derived from big data has become a prominent trend in this research field. Here, we provide an overview of known metabolites contributing to flavor in the major vegetables as well as genetic analyses of the relevant metabolic pathways based on different approaches, especially multi-omics. We present examples demonstrating how omics analyses can help us to understand the accomplishments of historical flavor breeding practices and implement further improvements. The integration of genetics, cultivation, and postharvest practices with genome-scale data analyses will create enormous potential for further flavor quality improvements.

Biomarkers of tuber intake

Tubers are important crops as well as staple foods in human nutrition. Among tubers, the potato in particular has been investigated for its health effects. However, except for its contribution to energy and effects related to resistant starch, the role of potatoes and other tubers in human health is still debated. In order to establish firm evidence for the health effects of dietary tubers and processed tuber products, it is essential to assess total intake accurately. The dietary assessment in most studies relies mainly on self-reporting and may give imprecise quantitative information on dietary intakes. Biomarkers of food intake (BFIs) are useful objective means to assess intake of specific foods or may be used as an additional measure to calibrate the measurement error in dietary reports. Here, intake biomarkers for common tubers, including potatoes and heated potato products, sweet potato, cassava, yam, and Jerusalem artichoke, are reviewed according to the biomarker of food intake reviews (BFIRev) standardized protocols for review and validation. Candidate BFIs for heated potato product include α-chaconine, α-solanine, and solanidine; less evidence is available to indicate peonidin 3-caffeoylsophoroside-5-glucoside and cyanidin 3-caffeoylsophoroside-5-glucoside as putative biomarkers having high potential specificity for purple sweet potato intake; linamarin may in addition be considered as a putative BFI for cassava. Other tubers also contain toxic glycosides or common contaminants as characteristic components but their putative use as intake biomarkers is not well documented. Alkyl pyrazines, acrylamide, and acrolein are formed during cooking of heated potato products while these have not yet been investigated for other tubers; these markers may not be specific only to heated potato but measurements of these compounds in blood or urine may be combined with more specific markers of the heated products, e.g., with glycoalkaloids to assess heated potato products consumption. Further studies are needed to assess the specificity, robustness, reliability, and analytical performance for the candidate tuber intake biomarkers identified in this review.

Utilisation of the MVA pathway to produce elevated levels of the sesquiterpene α-copaene in potato tubers

Potato flavour is a complex trait resulting from the presence of a combination of volatile and non-volatile compounds. The aim of this work was to investigate the effect of specifically altering the volatile content of tubers and assess its impact on flavour. Tuber-specific over-expression of a potato α-copaene synthase gene resulted in enhanced levels (up to 15-fold higher than controls) of the sesquiterpene α-copaene. A positive correlation (R(2)=0.8) between transgene expression level and α-copaene abundance was observed. No significant changes in the levels of volatiles other than α-copaene were detected. Non-volatile flavour compounds (sugars, glycoalkaloids, major umami amino acids and 5'-ribonucleotides) were also determined. Relationships between flavour compounds and sensory evaluation data were investigated. Evaluators could not detect any aroma differences in the transgenic samples compared with controls and no significant differences in taste attributes were found. Thus although successful engineering of potato tubers to accumulate high levels of the flavour volatile α-copaene was achieved, sensory analysis suggests that α-copaene is not a major component of potato flavour.

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.

Exogenous methyl jasmonate diminishes the formation of lipid-derived compounds in boiled potato (Solanum tuberosum L.)

BACKGROUND

During potato storage the tubers tend to develop off-flavours, mainly due to lipid-derived aldehydes, whose formation is increased after boiling or processing. This may become a problem when boiled or precooked potatoes are used. Methyl jasmonate (MJ) is a phytohormone capable of modifying plant and food composition. The aim of this work was to control the formation of off-flavours in different cultivars of raw potato during storage by MJ treatment.

RESULTS

The use of Carbowax 20M as support in MJ emulsion resulted in significantly (P < 0.05) lower levels of lipid-derived compounds than the use of lanolin. Levels of the lipid-derived aldehydes propanal, hep-2-enal, nonanal, oct-2-enal and hexanal, although dependent on variety, generally decreased significantly (P < 0.05) after treatment with MJ/Carbowax 20M emulsion. Sugar-derived compounds such as pyridine and furfural, however, were not affected by this treatment.

CONCLUSION

Treatment with MJ/Carbowax 20M can be used to diminish the formation of off-flavours in boiled potato. However, this treatment is not useful to avoid the sweetening caused by sugar-derived products. Additional advantages of exogenous MJ are a delay in the appearance of sprouting and aging and hence prolongation of the storage life of potato tubers.

Plant odor analysis of potato: response of guatemalan moth to above- and belowground potato volatiles

The Guatemalan moth Tecia solanivora is an invasive pest of potato in Central and South America. The larvae infest potato tubers in the field as well as in storage facilities. The headspace of potato foliage and potato tubers was studied with regard to volatiles that mediate host-finding and oviposition in the Guatemalan moth. Foliage of three phenological stages, from sprouting to tuberization and flowering, released more than 30 sesquiterpenes. The main compounds were beta-caryophyllene, germacrene-D-4-ol, germacrene-D, kunzeaol, and (E,E)-alpha-farnesene. Sesquiterpenes accounted for >90% of the headspace of green plants, whereas fresh potato tubers emitted only trace amounts of a few sesquiterpenes. Screening of headspace collections with antennae of Guatemalan moth females showed a strong response to several sesquiterpenes and monoterpenes that were emitted from foliage only. In addition, antennae responded to methyl phenylacetate, a floral fragrance that was released in large amounts from flowering plants and that was also present in tuber headspace. Female and male moths were attracted to methyl phenylacetate; this compound may accordingly contribute to female attraction to tuber-bearing potato plants in the field as well as to potato tubers in storage. Oviposition tests showed that females lay eggs near mature flowering plants. Eggs were laid in soil close to the plant and not on potato stems and foliage, which may be due to avoidance of terpenoid compounds released from green plant parts at close range. The results support the concept that potato volatiles mediate host-finding and oviposition behavior and that these compounds may become useful tools for management of the Guatemalan moth.

Expression profiling of potato germplasm differentiated in quality traits leads to the identification of candidate flavour and texture genes

Quality traits such as flavour and texture are assuming a greater importance in crop breeding programmes. This study takes advantage of potato germplasm differentiated in tuber flavour and texture traits. A recently developed 44,000-element potato microarray was used to identify tuber gene expression profiles that correspond to differences in tuber flavour and texture as well as carotenoid content and dormancy characteristics. Gene expression was compared in two Solanum tuberosum group Phureja cultivars and two S. tuberosum group Tuberosum cultivars; 309 genes were significantly and consistently up-regulated in Phureja, whereas 555 genes were down-regulated. Approximately 46% of the genes in these lists can be identified from their annotation and amongst these are candidates that may underpin the Phureja/Tuberosum trait differences. For example, a clear difference in the cooked tuber volatile profile is the higher level of the sesquiterpene alpha-copaene in Phureja compared with Tuberosum. A sesquiterpene synthase gene was identified as being more highly expressed in Phureja tubers and its corresponding full-length cDNA was demonstrated to encode alpha-copaene synthase. Other potential 'flavour genes', identified from their differential expression profiles, include those encoding branched-chain amino acid aminotransferase and a ribonuclease suggesting a mechanism for 5'-ribonucleotide formation in potato tubers on cooking. Major differences in the expression levels of genes involved in cell wall biosynthesis (and potentially texture) were also identified, including genes encoding pectin acetylesterase, xyloglucan endotransglycosylase and pectin methylesterase. Other gene expression differences that may impact tuber carotenoid content and tuber life-cycle phenotypes are discussed.

Umami compounds are a determinant of the flavor of potato (Solanum tuberosum L.)

Vegetable flavor is an important factor in consumer choice but a trait that is difficult to assess quantitatively. The purpose of this study was to assess the levels of the major umami compounds in boiled potato tubers, in cultivars previously assessed for sensory quality. The free levels of the major umami amino acids, glutamate and aspartate, and the 5'-nucleotides, GMP and AMP, were measured in potato samples during the cooking process. Tubers were sampled at several time points during the growing season. The levels of both glutamate and 5'-nucleotides were significantly higher in mature tubers of two Solanum phureja cultivars compared with two Solanum tuberosum cultivars. The equivalent umami concentration was calculated for five cultivars, and there were strong positive correlations with flavor attributes and acceptability scores from a trained evaluation panel, suggesting that umami is an important component of potato flavor.

Effect of cysteine and cystine addition on sensory profile and potent odorants of extruded potato snacks

Aromas generated in extruded potato snacks without and with addition of 0.25, 0.5, and 1% (w/w) of flavor precursors, cysteine and cystine, were compared and evaluated by descriptive sensory profiling. The results showed that high addition of cysteine (0.5 and 1%) resulted in the formation of undesirable odor and taste described as mercaptanic/sulfur, onion-like, and bitter; on the contrary, addition of cystine even at high concentration gave product with pleasant odor and taste, slightly changed into breadlike notes. GC/O analysis showed cysteine to be a much more reactive flavor precursor than cystine, stimulating formation of 12 compounds with garlic, sulfury, burnt, pungent/beer, cabbage/mold, meatlike, roasted, and popcorn odor notes. Further analysis performed by the AEDA technique identified 2-methyl-3-furanthiol (FD 2048) as a most potent odorant of extruded potato snacks with 1% addition of cysteine. Other identified compounds with high FD were butanal, 3-methyl-2-butenethiol, 2-methylthiazole, methional, 2-acetyl-1-pyrroline, and 3-hydroxy-4,5-dimethyl-2(5H)-furanone. In the case of cystine addition (1%) the highest FD factors were calculated for butanal, 2-acetyl-1-pyrroline, benzenemethanethiol, methional, phenylacetaldehyde, dimethyltrisulfide, 1-octen-3-ol, 1,5-octadien-3-one, and 2-acetylpyrazine.

Identification of potent odorants formed during the preparation of extruded potato snacks

Extrusion cooking processing followed by air-drying has been applied to obtain low-fat potato snacks. Optimal parameters were developed for a dough recipe. Dough contained apart from potato granules 7% of canola oil, 1% of salt, 1% of baking powder, 5% of maltodextrin, and 15% of wheat flour. After the extrusion process, snacks were dried at 85 degrees C for 15 min followed by 130 degrees C for 45 min. The potent odorants of extruded potato snacks were identified using aroma extract dilution analysis and gas chromatography-olfactometry. Among the characteristic compounds, methional with boiled potato flavor, benzenemethanethiol with pepper-seed flavor, 2-acetyl-1-pyrroline with popcorn flavor, benzacetaldehyde with strong flowery flavor, butanal with rancid flavor, and 2-acetylpyrazine with roasty flavor were considered to be the main contributors to the aroma of extruded potato snacks. Several compounds were concluded to be developed during extrusion cooking, such as ethanol, 3-methylbutanal, (Z)-1,5-octadien-3-one with geranium flavor, and unknown ones with the flavor of boiled potato, cumin, candy, or parsley root. Compounds such as methanethiol, 2,3-pentanedione, limonene, 2-acetylpyrazine, 2-ethyl-3,5-dimethylpyrazine, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, 3-hydroxy-4,5-dimethyl-2(5H)-furanone, 2-methyl-3,5-diethylpyrazine, 5-methyl-2,3-diethylpyrazine, and (E)-beta-damascenone were probably developed during air-drying of the potato extrudate.

Real-time flavor release from French fries using atmospheric pressure chemical ionization-mass spectrometry

Flavor release from French fries was measured with atmospheric pressure chemical ionization-mass spectrometry (APCI-MS) using both assessors (in vivo) and a mouth model system (in vitro). Several volatiles measured with APCI were identified with MS-MS. The effect of frying time, salt addition, and an alternative process using superheated steam was determined on I(max) (maximum intensity of compounds) and on t(max) (time of maximum intensity). In vitro a "chewing" frequency of 0.60 Hz caused an increased t(max) for low molecular weight compounds compared to the other frequencies tested. Above 0.93 Hz further increase in the frequency did not affect t(max). Trends observed with in vivo experiments could be verified with in vitro experiments. I(max) correlated well with frying time. Addition of salt resulted in a decreased t(max), suggesting a salting-out effect. The alternative process caused a layer of oil on the surface, and this resulted in a higher t(max), but no effect on I(max) was found. This phenomenon may be critical for the sensory quality and would not have been observed with static volatile measurements, demonstrating the value of flavor release measurements.