Virginia K. Corrigan

Winter squash (Cucurbita maxima) texture: Sensory, chemical, and physical measures

Abstract Significant differences were found in a wide variety of textural attributes in eight winter squash cultivars (Cucurbita maxima Duchesne) assessed at 4–5 and 9–10 weeks after harvest using both a trained sensory panel and an Instron Universal Testing Machine. The Instron texture profile analysis force‐displacement curves were distinctive for each of the eight cultivars tested, with behaviour under deformation forces indicating differences in the structure and composition of the tissue. Starch and logged dry matter contents varied significantly between cultivars, and were strongly correlated with all the sensory textural attributes rated, and with gumminess and hardness (dry matter only) measured by the Instron. Simple linear regressions indicated significant relationships between textural attributes as measured by the sensory panel and the Instron.

Sensory characteristics and consumer acceptability of ‘Pink Lady’ and other late‐season apple cultivars

Abstract ‘Pink Lady’ is a late maturing ‘Lady Williams’ × ‘Golden Delicious’ apple (Malus domestica Borkh.) cultivar developed in Western Australia and imported into New Zealand by the Ministry of Agriculture and Fisheries in 1986. We used trained and consumer panellists, and chemical and physical analyses, to compare the sensory quality of ‘Pink Lady’ with that of four standard late‐harvest apple cultivars. If acceptable, the new apple could usefully extend the harvest season of New Zealand apples. Trained taste panellists gave ‘Pink Lady’ apples similar ratings to ‘Braeburn’ and ‘Fuji’ apples for texture, sweet‐sour balance and flavour, but lower ratings for juiciness. ‘Pink Lady’ was a firm apple as measured by penetrometer, and Instron texture measurements indicated it was a hard, crisp apple. ‘Pink Lady’, ‘Braeburn’, and ‘Fuji’ apples were rated higher for acceptability than ‘Granny Smith’ and ‘Red Dougherty’ by the consumer panel, who said they would buy these cultivars and pay more for them. Consum...

Sugars and sweetness in buttercup squash

Sweetness is an important attribute in the flavour, acceptability, and perceived quality of winter squash. Glucose, fructose and sucrose contributed differently to the perceived sweetness of eight winter squash cultivars (Cucurbita maxima) rated by a trained sensory panel. Sucrose was the most important sugar in predicting sweetness, but better predictions were obtained using additional combinations of glucose and fructose content. Sugar content and relative proportions of glucose, fructose and sucrose changed during storage. Starch content decreased for all cultivars during storage, and was an important predictor of sweetness for high starch cultivars only. When data for sweetness were regressed against sugar concentrations, adjusted R2 values in the range of 0.68-0.89 were obtained for seven of the cultivars. Including starch in the regression models unproved the adjusted R2 values to 0.77-0.94.

Postharvest life of asparagus (Asparagus officinalis) under warm conditions can be extended by controlled atmosphere or water feeding

Abstract Green asparagus (Asparagus officinalis) is known to respond to controlled atmosphere storage (CA) at 20°C with increased shelf‐life, reduced respiratory rate, slower loss of soluble carbohydrates and protein, and slower accumulation of asparagine. This work investigated the likelihood of interactive effects of storage of spears in CA along with spear feeding solutions, including 2% sucrose. Standing the spears in a feeding solution extended shelf‐life in air but conferred little additional benefit in CA. Feeding the spears with 2% aqueous sucrose reduced asparagine accumulation and protein loss, but gave no visual benefit over water alone. Spears in the feeding solutions gained weight, particularly during the first 2 days after harvest, but weight gain was slower in CA than in air. Sensory assessment indicated that spears held in CA for 6 days had similar flavour and acceptability to spears held in air for 1 day. Spear quality was more strongly influenced by CA than by feeding solutions. Both approaches could assist in asparagus quality retention where a good refrigerated cool chain is not available, but these technologies are technically challenging to apply to air‐freighted asparagus.

Assessment of objective texture measurements for characterising and predicting the sensory quality of squash (Cucurbita maxima)

Abstract Ten squash (Cucurbita maxima) cultivars were assessed using a trained sensory panel and a range of objective measures. Significant differences between cultivars were found for most sensory, Instron texture profile analysis (TPA), and biochemical properties. Partial least squares (PLS) regression models using single objective TPA variables explained up to 75.7% of variance in squash textural attributes, whereas including multiple objective TPA variables and/or dry matter (DM) increased the variation explained to varying degrees. Sugars and DM explained up to 86.1% and 65.7% of variance in sweetness and flavour intensity ratings respectively. Principal components analysis (PCA) showed that the first two principle components explained 97.9% and 78.6% of variation in the sensory and objective TPA data, respectively. The PCA biplots appeared to group the cultivars on a similar basis, and results presented here for PCA and PLS regression suggest that objective measurements such as objective TPA values and/or DM data alone could be used to characterise some aspects of the sensory texture and flavour of squash.

Genetic analysis of sweetness and textural attributes in winter squash (Cucurbita maxima)

Abstract Quantitative genetics of chemical and textural attributes of quality of winter squash (Cucurbita maxima) were studied using the F1, F2, and backcrosses of the two crosses ‘Scarlet Warren’ × ‘CF2’ and ‘Scarlet Warren’ × ‘CF4’. The 3‐parameter additive‐dominance model adequately explained the variation among generation means of ‘Scarlet Warren’ × ‘CF2’ for dry matter (DM), alcohol‐insoluble solids, sucrose, glucose, fructose, soluble pectin, springiness, and adhesiveness but failed with total pectin, fracture hardness, and cohesiveness. Among generation means of ‘Scarlet Warren’ × ‘CF4’, the model explained the variation in all attributes except DM and springiness. Additive gene effects were negative for DM, alcohol‐insoluble solids, sucrose, soluble pectin, and adhesiveness but positive for glucose, fructose, total pectin, and springiness. Dominance gene effects were negative for alcohol‐insoluble solids and total pectin but positive for all three sugars, soluble pectin, springiness, and adhesiveness. Low heritability for most attributes other than sucrose indicated that environmental impacts (attributed to different growing climates for the two sites used for this study) were larger than genetic effects. Thus, breeding to produce sweeter squash is feasible, but breeding for textural improvement would seem to be problematic because the environment has an overriding effect on textural attributes.

Objective method for estimating sensory response to juiciness in apples

Abstract A modified method was used to measure moisture release from apples (Malus domestica Borkh.). The method was based on the area of spread of juice from the freshly cut surface of apple slices on CuSO4‐treated filter papers, measured as a ratio of the surface area of apple slice. A trained sensory panel of seven people rated four apple samples for juiciness over 10 sessions. From averaged panel ratings and transformed filter paper ratios, a logistic curve was fitted with an R2 of 0.92.

Effects of treatment with elevated carbon dioxide levels on the sensory quality of asparagus

Abstract Asparagus spears (Asparagus officinalis L. cv. Limbras 10) were stored for 3–5 days in atmospheres containing between 40 and 90% carbon dioxide (CO2) to evaluate the effect of insecticidal CO2 atmospheres on sensory quality based on sensory panel ratings of characteristic asparagus flavour, off‐flavours, flavour acceptability, andoverall acceptability. Sensory quality of spears after 4 days storage in 60% CO2 was similar to air‐stored spears but 5 days storage caused deterioration in the CO2‐stored spears relative to the air‐stored spears. Using higher CO2 levels than this for shorter storage times resulted in spears with CO2 injury and poor sensory quality. Spear quality deteriorated with shelf period but previous CO2 treatment did not affect the rate of deterioration. Storing spears at 5°C in 60% CO2 or 0°C in air gave consistently higher (lower for off‐flavours) sensory quality ratings for all characteristics assessed than vice versa. Thick spears had more flavour and were more acceptable than...