Genetic variation and relationship among content of vitamins, pigments, and sugars in baby leaf lettuce.

Ivan Simko

doi:10.1002/fsn3.1196

Abstract

Baby leaf lettuce harvested approximately 30 days after planting is the primary component of spring mix salads, a popular type of packaged salads. Very little is known, however, about the content of vitamins, sugars, and pigments in young lettuce plants. Therefore, plants of 42 accessions harvested at baby leaf stage were analyzed for the contents of vitamin C, ß‐carotene, anthocyanins, chlorophylls, glucose, fructose, and sucrose. Significant differences among accessions were found for content of all seven compounds plus sucrose sweetness equivalency (SSE) and average vitamin load (AVLAC). “Floricos” was highest in all sugars, SSE and vitamin C; “Taiwan” was highest in ß‐carotene and AVLAC, and “Annapolis” and “Darkland” were highest for anthocyanins and chlorophyll contents, respectively. The lowest content of glucose and sucrose was found in iceberg “Salinas,” fructose in L. serriola accession UC96US23, vitamin C in PI 257288, and β‐carotene in “Solar.” The lowest relative sweetness (SSE) was calculated for UC96US23, followed by “Salinas,” while the lowest AVLAC was estimated for PI 257288. There were very strong, positive correlations among contents of the three sugars, and between β‐carotene and vitamin C, and β‐carotene and anthocyanins. Composition profiles of accessions presented in this study, together with identified associations between compounds, can be used by breeders, growers, and producers to select lettuces with desirable combinations of sugars, pigments, and vitamins. This information can help in development of new cultivars and breeding lines with desirable combination of traits, pleasing taste, and higher vitamin content.

Highlights

Lettuce (Lactuca sativa L.) is the most popular, commercially grown leafy vegetable in many countries around the world (Simko, Hayes, Mou, & McCreight, 2014)
(“Floricos”) with μ = 0.3 g per kg of fresh weight (g/kg FW) (Table 1, Figure S1), vitamin C from 61 mg/kg FW (PI 257288) to 197 mg/kg FW (“Floricos”) with μ = 123 mg/kg FW, β‐carotene from 15 mg/kg FW (“Solar”) to 153 mg/kg FW (“Taiwan”) with μ = 49 mg/kg FW, chlorophylls from 28 SPAD (“La Brillante”) to 52 SPAD (“Darkland”) with μ = 41 SPAD, and anthocyanins from 3.3 ACI (“La Brillante”) to 17.9 ACI (“Annapolis”) with μ = 7.7 ACI (Table 1, Figure S2). These values are similar to those previously reported for the content of chlorophylls (Xu & Mou, 2015), anthocyanins (Mamo et al, 2019) (Simko I, 2019, unpublished data), vitamin C (Albrecht, 1993; Mampholo, Maboko, Soundy, & Sivakumar, 2016), β‐carotene (Cassetari et al, 2015; Mampholo et al, 2016; Mou, 2005), glucose, fructose, and sucrose (Smoleń et al, 2015) in young or mature lettuce plants
The largest content of all three sugars was detected in romaine type “Floricos,” while the lowest contents of sugars were found in iceberg type “Salinas” and the L. serriola accession UC96US23

Summary

Introduction

Lettuce (Lactuca sativa L.) is the most popular, commercially grown leafy vegetable in many countries around the world (Simko, Hayes, Mou, & McCreight, 2014). Baby leaf lettuce is the primary component of spring mix salads that are popular type in packaged salads. Lettuce for baby leaf production is harvested when the first four true leaves reach the length of circa 5–13 cm, approximately 30 days after planting. Food Science & Nutrition published by Wiley Periodicals, Inc

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